Bondline - User contributions [en]

Charging Systems

2009-04-06T12:41:14Z

Mboyd: /* Mike Boyd's Adaptation of Bob's Method */

__TOC__

== The Basics ==

The battery stores power chemically, the alternator converts the engine's rotating motion into electrical energy, the Voltage Regulator (also known as the "Alternator Control Unit", or ACU) controls the alternator's output to keep the battery charged, but not over charged (which results in boiling out its acid).

For a more detailed explanation of charging system operation and theory, a quick Google search usually does the trick. Rather than rehash the theory here, [http://www.rowand.net/Shop/Tech/AlternatorGeneratorTheory.htm Rowand.net] has a fairly good explanation of how generators and alternators work as well as the regulator.

== Troubleshooting ==

'''Mechanical Difficulty:'''[[Image:Wrench2.jpg]]

'''The usual scenario''' ... Your battery started discharging during your last flight. You shed loads by turning off unneeded equipment until you arrived at the airport and landed normally. Congrats on handling the in flight portion properly. Now how do you get it repaired?

You need to find out exactly which part failed. The usual FBO response is to replace the alternator AND the voltage regulator. They don't have to do much troubleshooting and they sell lots of expensive parts. A Field Rep for [http://www.kellyaerospace.com/index.html Kelly Aerospace], one of the largest OH shops for alternators, came to an FAA Safety meeting and told the attendees that 8 out of 10 alternators returned to them as cores for OH worked when tested before disassembly. He stated that A&P mechanics in the field were NOT doing their job properly, and that better troubleshooting techniques were needed, rather than replacing so many functional alternators.

If you have a Volt-Ohm meter, you can save lots of time and money. Inexpensive voltmeters are widely available from such vendors as [http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=92020 Harbor Freight] and [http://www.radioshack.com/product/index.jsp?productId=2103534 Radio Shack], often for as little as $10.

To help you know what wire goes where, the maintenance manual has detailed schematics. Gary Vogt has re-drawn the [http://www.aucountry.com/ACA_Folder/Technical/Wire_Scan_76-77.jpg 76-77] and the [http://www.aucountry.com/ACA_Folder/Technical/Wire_Scan_78-79.jpg 78-79] Tiger/Cheetah schematics in a little less technical detail.

All the troubleshooting described below is done with the engine OFF and the keys in your pocket.

Open the cowl and locate the voltage regulator. On Grumman American singles its on the passenger side just inboard of the motor mount attach point, directly above the battery. On AA-5x you'll see a connector on the bottom with several wires. Look closely and you'll see that they are marked with letters on the regulator. On AA-1x there are only 2 wires and they are crimped to the airframe wiring harness without any quick disconnects.

Visually check all of the wires and their crimped fittings. Pull gently on the crimped fittings, none of them should be loose. After 30+ years in service all these wires warrant close examination. Generally inspect the wires for large cracks in the insulation, or, where appropriate, the shielding. Look for breaks in the shielding pigtails.

Turn on the Master switch.

=== AA-5x series 12V ===

Locate the "S" terminal on the AA-5x regulator. Using your VOM, measure the voltage between the S terminal on the regulator and a good ground such as the battery's negative terminal. The VOM should read close to 12.6 volts on a fully charged battery. In this example, however, your battery is not fully charged after the in-flight failure of the charging system, so a measurement equal to 10 volts or greater is acceptable. If an acceptable voltage is present, then your Master Switch, Master Relay, Alt Field Circuit Breaker and the associated wiring are all working well enough to charge the battery from the alternator. Continue to the next step.

Locate the "F" terminal and measure the voltage just as you did at the "S" terminal. As before, if the measured voltage is within a couple of volts of the nominal battery voltage, then the regulator is correctly trying to "excite" the alternator field so that the alternator can produce an output. Continue to the next step.

Reset the VOM to measure resistance instead of voltage. Remove the "F" wire from the regulator and measure between the wire and ground. You should measure less than 10 ohms of resistance, and usually about 5 ohms. If you have significantly higher resistance (say 20 ohms or more) then there are problems with the alternator field or brushes, or possibly the wiring going to the alternator is in bad condition. A reading of less than 5 ohms, would indicate a short in the Field wire or inside the alternator. Otherwise, since you have the appropriate resistance between the "F" wire and ground, you are through checking the easy stuff, and are ready to pull the nose bowl.

=== AA-1x series ===

Locate the "I" terminal wire on the AA-1x regulator. Using your VOM, measure the voltage between the I wire on the regulator and a good ground such as the battery's negative terminal. The VOM should read close to 12.6 volts on a fully charged battery. In this example, however, your battery is not fully charged after the in-flight failure of the charging system, so a measurement equal to 10 volts or greater is acceptable. If an acceptable voltage is present, then your Master Switch, Master Relay, Alt Field Circuit Breaker and the associated wiring are all working well enough to charge the battery from the alternator. Continue to the next step.

Locate the "F" wire and measure the voltage just as you did at the "I" wire. As before, if the measured voltage is within a couple of volts of the nominal battery voltage, then the regulator is correctly trying to "excite" the alternator field so that the alternator can produce an output. Continue to the next step.

Reset the VOM to measure resistance instead of voltage. Disconnect the "F" wire from the regulator and measure between the wire and ground. You should measure less than 10 ohms of resistance, and usually about 5 ohms. If you have significantly higher resistance (say 20 ohms or more) then there are problems with the alternator field or brushes, or possibly the wiring going to the alternator is in bad condition. A reading of less than 5 ohms, would indicate a short in the Field wire or inside the alternator. Otherwise, since you have the appropriate resistance between the "F" wire and ground, you are through checking the easy stuff, and are ready to pull the nose bowl.

=== Turn OFF the Master at this time ===

We are through with the powered portion of the testing, so turn off the Master switch.

Right about now you are wishing that you had installed the split nose bowl STC, because without it you have to remove the propeller to gain access to the alternator.

'''Mechanical Difficulty:''' [[Image:Wrench3.jpg]]

Up to this point, we were just CHECKING electrical measurements without any actual disassembly of the plane. If you do not have the split nose bowl STC, then this is the point at which you will require A&P supervision to complete the testing, removal and replacement of the alternator, prop, mounting bracket, etc. [http://www.airweb.faa.gov/Regulatory_and_Guidance_Library%5CrgFAR.nsf/0/AC9BED30F1D032B9852566AB006BC89C?OpenDocument FAR 43 Appendix A paragraph (c)(19)] permits the owner/pilot to remove and install cowlings without A&P supervision, if the prop does not have to be removed, after demonstrating the ability to do it correctly.

On all 2 place and on Travelers before 75, you can check the wiring by removing the screws on the right-hand lower cowling and letting the cowl side tip out from the firewall and nose bowl just enough to enable you to reach under the front cylinder and touch the wires on the back of the alternator. On 75 Travelers with the "Cheetah nose" and on all Cheetahs and Tigers, you have to remove the nose bowl to continue troubleshooting. That's OK, because you have already narrowed the source of the problem to that area anyway.

With the nose bowl off, or at least the lower nose off if you have the split nose, now remove the alternator belt from the pulley. Our testing so far has not ruled out a worn, loose, or missing alternator belt, so make certain that the belt is in good condition and properly tensioned.

The required amount of tension on this belt is often underestimated. The amount of power required to turn the alternator increases as the SQUARE of its output (charging) current! Lycoming's service information was updated a couple years back, and they now suggest setting belt tension by checking to see if the belt will slip before reaching a specified torque. You can check this by putting a socket on the alternator drive pulley nut and setting a torque wrench to 540 in-lb (45 ft-lb), and then holding the prop and trying to turn the alternator (CCW when viewing it from the front) with the torque wrench. The wrench should indicate 540 in-lb BEFORE the pulley slips. The older method mentioned in the Maintenance Manual, no longer favored by Lycoming, was to press in the center of the belt span between the pulleys and measure the deflection. New belts were to have less deflection than those that were worn. Refer to the maintenance manual if you don't have a torque wrench handy.

If the belt itself is in good condition and is tensioned correctly, the next step is to remove the alternator for inspection. First release the tension on the belt. To do this, cut the safety wire on the bolt holding the alternator to the bracket, then loosen the bolt enough so that you are able to push the alternator up, thus relieving the belt tension.

In the next step, you remove the alternator, which is quite heavy. If you have a portable service table or stand, now would be a good time to position it under the alternator. Now remove the big bolt at the bottom of the alternator (the one that holds it to the engine mounting bracket). While supporting the alternator so the wiring is not stressed, remove the bolt that was safety wired. The alternator should slide off the engine mounting bracket and be attached only by the wiring on the back.

Carefully turn the alternator around, and lift the rubber boot that hides the connection of the big wire to the back of the alternator. This is a VERY common failure point on the aging fleet. The wire breaks off the ring lug that is bolted down, and the alternator output is prevented from flowing back to the battery by the broken connection. Look also at the small wire that is bolted to the same connection. This is the "A" or sense wire which tells the Voltage Regulator what the alternator is doing. The sense wire is also a common failure point, though not as often as the larger output wire. Look at the other small wire which attaches to a different post. This is the "F" or field wire. If the resistance checks were normal earlier, then this wire should be fine; nevertheless, after 30+ years in service all these wires warrant close examination. Inspect the wires for cracks in the insulation, or, where appropriate, the shielding. Make sure the shield grounds at both ends of the F and A wires are in good condition and still connected, and check the sheilding pigtails behind the alternator, they can rub on the baffling and get worn through.

If there are no obvious failures in the wiring, you need to mark them and remove them so that the alternator can be tested at a shop. Pep-Boys and AutoZone will check your alternator for free. If you have an AA-5x series, then tell them its from a 71 Ford Pickup with AC. That is the actual original application for the Ford DOFF-10300J alternator on your Traveler/Cheetah/Tiger. AA-1x use a Prestolite brand alternator, and they should have no trouble figuring out the connections.

After the alternator is spun up and bench tested, all but the rarest and intermittent failures will have been diagnosed, and you will be repairing JUST the wiring, or replacing the alternator or the voltage regulator, and NOT spending money on needless repairs.

Prior to installing the alternator, carefully inspect the U shaped mounting bracket for cracks. They are prone to crack across the middle of the U, often into one of the bolt holes. Replacement brackets are available from any Lycoming distributor or from FletchAir.

== Replacement Parts ==

=== Alternator and Regulator ===
If the alternator or regulator have failed, you may want to consider a modern replacement than have the old stuff overhauled. Honestly, for about the same price as an overhaul, you can have a new alternator. [http://www.plane-power.com/products.htm Plane Power] makes a PMA'd alternator that is about 1 lb lighter, and they claim that it makes power at lower RPM. They also make a PMA'd modern solid state voltage regular. Zeftronics is also a popular solid state regulator replacement. If either the alternator or regulator has failed, have the other tested. In some cases, a failure in one of these causes problems in the other.

=== Plane Plastics Battery Box ===
Original style replacement battery boxes are no longer available. [http://www.fletchair.com Fletchair] sells the [http://www.planeplastics.com/ Plane Plastics] PMA replacement part but several have had questions on how to attach the drain hose to the larger nub on the bottom of that box. You should avoid using metal fittings to attach the hose since battery acid doesn't react well with metals and can corrode and clog the tube.

==== Bob Steward's Approach ====
Bob Steward came up with the following method for attaching the hose to the bottom of the box (presented here with his permission).
# Drill a hole in the bottom of the nub sufficient for the drain hose (available from Lowes, Home Depot, Aquarium store) to fit loosely.
# Dip the end of the hose in ABS Cement (blue can @ Lowes in the plumbing department) a couple times to coat it well.
# Paint the ID of the nub with the same cement and let the MEK solvent soften the box.
# Dip tube again and insert in box (from the bottom up) so the tube is almost even with or a little below the bottom of the box.
# Paint more cement around it, such that the nub is filled with the ABS cement so that acid won't pool around the plastic tube and create a standpipe.
# Secure the drain hose such that the box can be left sitting upright for several hours (overnight if the temps are low) as the solvent flashes off.
When the cement has hardened, the pipe will be glued in place, the excess space from the pipe to the nub will be filled with the same material (ABS plastic) that the box was formed from, and a little drill/countersink work will open the tube and smooth the transition from the bottom of the box into the drain.

==== Mike Boyd's Adaptation of Bob's Method ====
Given how bad the vinyl tube on my original battery box looked, I wanted the ability to easily replace it on the new box. I was able to find a poly barbed nipple that was small enough to fit in the nub at my local Ace Hardware store (my local Home Depot and Lowes did not stock them). So, here is another option for those wondering how to setup the replacement battery box. I do not know if the hose on my Cheetah is the typical size so adjust the sizes as needed to fit your situation.

[[Image:battbox_parts.jpg|thumb|200px]]
[[Image:battbox_glue.jpg|thumb|200px]]
[[Image:battbox_finished.jpg|thumb|200px]]

What you'll need:
* Plane Plastics PMA'd battery box.
* 1 foot of 3/8" id (1/2" od) vinyl drain tube.
* 3/8" poly or nylon barbed fitting with 1/8" NPT (pipe thread) end.
* ABS plastic cement (not PVC or others, must be a combination of MEK and ABS resin).
* Drill bit sized to allow fitting to be press-fit into box OR 11/32 drill bit and 1/8 NPT tap.
* Hose clamp

The procedure is similar to Bob's approach, but instead of gluing the hose into the nub, you glue the fitting into the nub. For those that like step-by-step and pictures, here's the process:

# Drill hole in bottom of the nub.
# Thread the hole with the tap, should give about 2~3 threads. (optional)
# Screw or press (depending on method chosen) the fitting into the hole in the nub on the box. The fitting should now stay attached to the box on it's own.
# Set the box above some newspaper so it stands up and the drain points down (I found a couple pieces of 2x4 worked well).
# Take the brush in the cap of the ABS glue bottle, let it stop dripping, then place it into the nub on the inside of the box so it applies a coat of glue on the bottom of the nub.
# Let the glue dry for a few minutes and then remove any of the plastic that dripped down into the nipple. Should be able to easily pull the dried plastic out from the bottom. Also remove any ridges that may prevent drainage into the nub.
# Repeat the last two steps until it builds up enough plastic so any water (or acid) will not pool up in the nub but will flow down thru the fitting. The glue should do this naturally once you have applied enough.
# Push one end of the tubing over the fitting and secure with the clamp.
# Place the battery box in the plane and thread the tube thru the drain hole in the cowl.
# Cut the tube as needed so the tube extends past the cowl like the previous one (should be around a couple inches).

You'll need to cut out the slots for the battery cables (I found a Dremmel tool worked OK for this) since the box comes basically unprepared. That's it. You should now have a battery box that will function as intended.

Charging Systems

2009-04-06T02:48:22Z

Mboyd: /* Plane Plastics Battery Box */

__TOC__

== The Basics ==

The battery stores power chemically, the alternator converts the engine's rotating motion into electrical energy, the Voltage Regulator (also known as the "Alternator Control Unit", or ACU) controls the alternator's output to keep the battery charged, but not over charged (which results in boiling out its acid).

For a more detailed explanation of charging system operation and theory, a quick Google search usually does the trick. Rather than rehash the theory here, [http://www.rowand.net/Shop/Tech/AlternatorGeneratorTheory.htm Rowand.net] has a fairly good explanation of how generators and alternators work as well as the regulator.

== Troubleshooting ==

'''Mechanical Difficulty:'''[[Image:Wrench2.jpg]]

'''The usual scenario''' ... Your battery started discharging during your last flight. You shed loads by turning off unneeded equipment until you arrived at the airport and landed normally. Congrats on handling the in flight portion properly. Now how do you get it repaired?

You need to find out exactly which part failed. The usual FBO response is to replace the alternator AND the voltage regulator. They don't have to do much troubleshooting and they sell lots of expensive parts. A Field Rep for [http://www.kellyaerospace.com/index.html Kelly Aerospace], one of the largest OH shops for alternators, came to an FAA Safety meeting and told the attendees that 8 out of 10 alternators returned to them as cores for OH worked when tested before disassembly. He stated that A&P mechanics in the field were NOT doing their job properly, and that better troubleshooting techniques were needed, rather than replacing so many functional alternators.

If you have a Volt-Ohm meter, you can save lots of time and money. Inexpensive voltmeters are widely available from such vendors as [http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=92020 Harbor Freight] and [http://www.radioshack.com/product/index.jsp?productId=2103534 Radio Shack], often for as little as $10.

To help you know what wire goes where, the maintenance manual has detailed schematics. Gary Vogt has re-drawn the [http://www.aucountry.com/ACA_Folder/Technical/Wire_Scan_76-77.jpg 76-77] and the [http://www.aucountry.com/ACA_Folder/Technical/Wire_Scan_78-79.jpg 78-79] Tiger/Cheetah schematics in a little less technical detail.

All the troubleshooting described below is done with the engine OFF and the keys in your pocket.

Open the cowl and locate the voltage regulator. On Grumman American singles its on the passenger side just inboard of the motor mount attach point, directly above the battery. On AA-5x you'll see a connector on the bottom with several wires. Look closely and you'll see that they are marked with letters on the regulator. On AA-1x there are only 2 wires and they are crimped to the airframe wiring harness without any quick disconnects.

Visually check all of the wires and their crimped fittings. Pull gently on the crimped fittings, none of them should be loose. After 30+ years in service all these wires warrant close examination. Generally inspect the wires for large cracks in the insulation, or, where appropriate, the shielding. Look for breaks in the shielding pigtails.

Turn on the Master switch.

=== AA-5x series 12V ===

Locate the "S" terminal on the AA-5x regulator. Using your VOM, measure the voltage between the S terminal on the regulator and a good ground such as the battery's negative terminal. The VOM should read close to 12.6 volts on a fully charged battery. In this example, however, your battery is not fully charged after the in-flight failure of the charging system, so a measurement equal to 10 volts or greater is acceptable. If an acceptable voltage is present, then your Master Switch, Master Relay, Alt Field Circuit Breaker and the associated wiring are all working well enough to charge the battery from the alternator. Continue to the next step.

Locate the "F" terminal and measure the voltage just as you did at the "S" terminal. As before, if the measured voltage is within a couple of volts of the nominal battery voltage, then the regulator is correctly trying to "excite" the alternator field so that the alternator can produce an output. Continue to the next step.

Reset the VOM to measure resistance instead of voltage. Remove the "F" wire from the regulator and measure between the wire and ground. You should measure less than 10 ohms of resistance, and usually about 5 ohms. If you have significantly higher resistance (say 20 ohms or more) then there are problems with the alternator field or brushes, or possibly the wiring going to the alternator is in bad condition. A reading of less than 5 ohms, would indicate a short in the Field wire or inside the alternator. Otherwise, since you have the appropriate resistance between the "F" wire and ground, you are through checking the easy stuff, and are ready to pull the nose bowl.

=== AA-1x series ===

Locate the "I" terminal wire on the AA-1x regulator. Using your VOM, measure the voltage between the I wire on the regulator and a good ground such as the battery's negative terminal. The VOM should read close to 12.6 volts on a fully charged battery. In this example, however, your battery is not fully charged after the in-flight failure of the charging system, so a measurement equal to 10 volts or greater is acceptable. If an acceptable voltage is present, then your Master Switch, Master Relay, Alt Field Circuit Breaker and the associated wiring are all working well enough to charge the battery from the alternator. Continue to the next step.

Locate the "F" wire and measure the voltage just as you did at the "I" wire. As before, if the measured voltage is within a couple of volts of the nominal battery voltage, then the regulator is correctly trying to "excite" the alternator field so that the alternator can produce an output. Continue to the next step.

Reset the VOM to measure resistance instead of voltage. Disconnect the "F" wire from the regulator and measure between the wire and ground. You should measure less than 10 ohms of resistance, and usually about 5 ohms. If you have significantly higher resistance (say 20 ohms or more) then there are problems with the alternator field or brushes, or possibly the wiring going to the alternator is in bad condition. A reading of less than 5 ohms, would indicate a short in the Field wire or inside the alternator. Otherwise, since you have the appropriate resistance between the "F" wire and ground, you are through checking the easy stuff, and are ready to pull the nose bowl.

=== Turn OFF the Master at this time ===

We are through with the powered portion of the testing, so turn off the Master switch.

Right about now you are wishing that you had installed the split nose bowl STC, because without it you have to remove the propeller to gain access to the alternator.

'''Mechanical Difficulty:''' [[Image:Wrench3.jpg]]

Up to this point, we were just CHECKING electrical measurements without any actual disassembly of the plane. If you do not have the split nose bowl STC, then this is the point at which you will require A&P supervision to complete the testing, removal and replacement of the alternator, prop, mounting bracket, etc. [http://www.airweb.faa.gov/Regulatory_and_Guidance_Library%5CrgFAR.nsf/0/AC9BED30F1D032B9852566AB006BC89C?OpenDocument FAR 43 Appendix A paragraph (c)(19)] permits the owner/pilot to remove and install cowlings without A&P supervision, if the prop does not have to be removed, after demonstrating the ability to do it correctly.

On all 2 place and on Travelers before 75, you can check the wiring by removing the screws on the right-hand lower cowling and letting the cowl side tip out from the firewall and nose bowl just enough to enable you to reach under the front cylinder and touch the wires on the back of the alternator. On 75 Travelers with the "Cheetah nose" and on all Cheetahs and Tigers, you have to remove the nose bowl to continue troubleshooting. That's OK, because you have already narrowed the source of the problem to that area anyway.

With the nose bowl off, or at least the lower nose off if you have the split nose, now remove the alternator belt from the pulley. Our testing so far has not ruled out a worn, loose, or missing alternator belt, so make certain that the belt is in good condition and properly tensioned.

The required amount of tension on this belt is often underestimated. The amount of power required to turn the alternator increases as the SQUARE of its output (charging) current! Lycoming's service information was updated a couple years back, and they now suggest setting belt tension by checking to see if the belt will slip before reaching a specified torque. You can check this by putting a socket on the alternator drive pulley nut and setting a torque wrench to 540 in-lb (45 ft-lb), and then holding the prop and trying to turn the alternator (CCW when viewing it from the front) with the torque wrench. The wrench should indicate 540 in-lb BEFORE the pulley slips. The older method mentioned in the Maintenance Manual, no longer favored by Lycoming, was to press in the center of the belt span between the pulleys and measure the deflection. New belts were to have less deflection than those that were worn. Refer to the maintenance manual if you don't have a torque wrench handy.

If the belt itself is in good condition and is tensioned correctly, the next step is to remove the alternator for inspection. First release the tension on the belt. To do this, cut the safety wire on the bolt holding the alternator to the bracket, then loosen the bolt enough so that you are able to push the alternator up, thus relieving the belt tension.

In the next step, you remove the alternator, which is quite heavy. If you have a portable service table or stand, now would be a good time to position it under the alternator. Now remove the big bolt at the bottom of the alternator (the one that holds it to the engine mounting bracket). While supporting the alternator so the wiring is not stressed, remove the bolt that was safety wired. The alternator should slide off the engine mounting bracket and be attached only by the wiring on the back.

Carefully turn the alternator around, and lift the rubber boot that hides the connection of the big wire to the back of the alternator. This is a VERY common failure point on the aging fleet. The wire breaks off the ring lug that is bolted down, and the alternator output is prevented from flowing back to the battery by the broken connection. Look also at the small wire that is bolted to the same connection. This is the "A" or sense wire which tells the Voltage Regulator what the alternator is doing. The sense wire is also a common failure point, though not as often as the larger output wire. Look at the other small wire which attaches to a different post. This is the "F" or field wire. If the resistance checks were normal earlier, then this wire should be fine; nevertheless, after 30+ years in service all these wires warrant close examination. Inspect the wires for cracks in the insulation, or, where appropriate, the shielding. Make sure the shield grounds at both ends of the F and A wires are in good condition and still connected, and check the sheilding pigtails behind the alternator, they can rub on the baffling and get worn through.

If there are no obvious failures in the wiring, you need to mark them and remove them so that the alternator can be tested at a shop. Pep-Boys and AutoZone will check your alternator for free. If you have an AA-5x series, then tell them its from a 71 Ford Pickup with AC. That is the actual original application for the Ford DOFF-10300J alternator on your Traveler/Cheetah/Tiger. AA-1x use a Prestolite brand alternator, and they should have no trouble figuring out the connections.

After the alternator is spun up and bench tested, all but the rarest and intermittent failures will have been diagnosed, and you will be repairing JUST the wiring, or replacing the alternator or the voltage regulator, and NOT spending money on needless repairs.

Prior to installing the alternator, carefully inspect the U shaped mounting bracket for cracks. They are prone to crack across the middle of the U, often into one of the bolt holes. Replacement brackets are available from any Lycoming distributor or from FletchAir.

== Replacement Parts ==

=== Alternator and Regulator ===
If the alternator or regulator have failed, you may want to consider a modern replacement than have the old stuff overhauled. Honestly, for about the same price as an overhaul, you can have a new alternator. [http://www.plane-power.com/products.htm Plane Power] makes a PMA'd alternator that is about 1 lb lighter, and they claim that it makes power at lower RPM. They also make a PMA'd modern solid state voltage regular. Zeftronics is also a popular solid state regulator replacement. If either the alternator or regulator has failed, have the other tested. In some cases, a failure in one of these causes problems in the other.

=== Plane Plastics Battery Box ===
Original style replacement battery boxes are no longer available. [http://www.fletchair.com Fletchair] sells the [http://www.planeplastics.com/ Plane Plastics] PMA replacement part but several have had questions on how to attach the drain hose to the larger nub on the bottom of that box. You should avoid using metal fittings to attach the hose since battery acid doesn't react well with metals and can corrode and clog the tube.

==== Bob Steward's Approach ====
Bob Steward came up with the following method for attaching the hose to the bottom of the box (presented here with his permission).
# Drill a hole in the bottom of the nub sufficient for the drain hose (available from Lowes, Home Depot, Aquarium store) to fit loosely.
# Dip the end of the hose in ABS Cement (blue can @ Lowes in the plumbing department) a couple times to coat it well.
# Paint the ID of the nub with the same cement and let the MEK solvent soften the box.
# Dip tube again and insert in box (from the bottom up) so the tube is almost even with or a little below the bottom of the box.
# Paint more cement around it, such that the nub is filled with the ABS cement so that acid won't pool around the plastic tube and create a standpipe.
# Secure the drain hose such that the box can be left sitting upright for several hours (overnight if the temps are low) as the solvent flashes off.
When the cement has hardened, the pipe will be glued in place, the excess space from the pipe to the nub will be filled with the same material (ABS plastic) that the box was formed from, and a little drill/countersink work will open the tube and smooth the transition from the bottom of the box into the drain.

==== Mike Boyd's Adaptation of Bob's Method ====
Given how bad the vinyl tube on my original battery box looked, I wanted the ability to easily replace it on the new box. I was able to find a poly barbed nipple that was small enough to fit in the nub at my local Ace Hardware store (my local Home Depot and Lowes did not stock them). So, here is another option for those wondering how to setup the replacement battery box. I do not know if the hose on my Cheetah is the typical size so adjust the sizes as needed to fit your situation.

[[Image:battbox_parts.jpg|thumb|200px]]
[[Image:battbox_glue.jpg|thumb|200px]]
[[Image:battbox_finished.jpg|thumb|200px]]

What you'll need:
* Plane Plastics PMA'd battery box.
* 1 foot of 3/8" id (1/2" od) vinyl drain tube.
* 3/8" poly or nylon barbed fitting with 1/8" NPT (pipe thread) end.
* ABS plastic cement (not PVC or others, must be a combination of MEK and ABS resin).
* Drill bit sized to allow fitting to be press-fit into box OR 11/32 drill bit and 1/8 NPT tap.
* Hose clamp

The procedure is similar to Bob's approach, but instead of gluing the hose into the nub, you glue the fitting into the nub. For those that like step-by-step and pictures, here's the process:

# Drill hole in bottom of the nub.
# Thread the hole with the tap, should give about 2~3 threads. (optional)
# Screw or press (depending on method chosen) the fitting into the hole in the nub on the box. The fitting should now stay attached to the box on it's own.
# Set the box above some newspaper so it stands up and the drain points down (I found a couple pieces of 2x4 worked well).
# Take the brush in the cap of the ABS glue bottle, let it stop dripping, then place it into the nub on the inside of the box so it applies a coat of glue on the bottom of the nub.
# Let the glue dry for a few minutes and then remove any of the plastic that dripped down into the nipple. Should be able to easily pull the dried plastic out from the bottom.
# Repeat the last two steps until it builds up enough plastic so any water (or acid) will not pool up in the nub but will flow down thru the fitting. The glue should do this naturally once you have applied enough.
# Push one end of the tubing over the fitting and secure with the clamp.
# Place the battery box in the plane and thread the tube thru the drain hole in the cowl.
# Cut the tube as needed so the tube extends past the cowl like the previous one (should be around a couple inches).

You'll need to cut out the slots for the battery cables (I found a Dremmel tool worked OK for this) since the box comes basically unprepared. That's it. You should now have a battery box that will function as intended.

File:Battbox finished.jpg

2009-04-06T02:03:16Z

Mboyd: The finished battery box with the barbed nipple installed on the nub.

The finished battery box with the barbed nipple installed on the nub.

File:Battbox glue.jpg

2009-04-06T02:02:17Z

Mboyd: Adding the barbed fitting to the battery box, glued in so it will drain properly.

Adding the barbed fitting to the battery box, glued in so it will drain properly.

File:Battbox parts.jpg

2009-04-06T02:00:57Z

Mboyd: Parts needed for PlanePlastics battery box setup.

Parts needed for PlanePlastics battery box setup.

Charging Systems

2009-04-05T14:05:10Z

Mboyd: /* Replacement Parts */

What I've Learned

2008-08-14T14:06:18Z

Mboyd: /* Introduction */

== Introduction ==

This is part three (3) of a three (3) part article about Mike (and his '76 AA5A).

# [[The_Annual_Inspection | The Annual Inspection]]
# [[The Replies]]
# What I've Learned

== Part 3: What I've Learned ==

Since my original post, what I found out was that this shop lost several of their more experienced A&P's that they had just a few years ago and the one that performed my annual just didn't meet my expectations for attention to detail and did not refer to the maintenance manuals that the shop provides for him as often as I would have hoped (as in the case of the dorsal fin removal). As I recall, one of my responses to a private e-mail sent after my original post included the phrase "You can lead an A&P to the Grumman manual, but you can't make him read it" and to me that seems to sum it up.

I'm now using another mechanic and am much happier with their performance. Although my new shop has more experience with those C model aircraft, they appear to me to be much more detail oriented and capable than the first shop (I interviewed the owner and the head mechanic for about an hour each). They have a service that provides them with the manuals for almost all smaller aircraft and demonstrated the system to me. They have fixed many of the problems caused by the first annual and have not caused any additional ones (definitely a step in the right direction).

Here's what I've learned from this experience:

* Do your homework. I can't emphasize this enough. If you are reading this, you are probably well on your way to doing that. Find out what to expect from a pre-buy or annual inspection (get the checklists from the maintenance manual, etc). Interview potential mechanics and get references. Talk to other pilots in your area. If you don't have copies of the maintenance and parts manual, get them.
* Find a "good" mechanic. Choose a detail-oriented mechanic. A good mechanic that doesn't have as much experience with Grummans is much better than the inverse. Beware of high turn-over rates of mechanics at a given shop (seeing lots of new faces and no old ones at your favorite shop?). Make sure they have, and use, any appropirate manuals.
* Be an active participant in your airplane care. Be there for pre-purchase inspections, annuals, etc. Using that homework you can follow along with the mechanic and ask questions. If your mechanic will allow, "owner-assist" on the work. One of the mistakes I made during the annual was that I was not there the entire time. Until you are intimately comfortable with the mechanics work, be there.
* If it doesn't "feel right" it probably isn't. Be it the mechanic, a problem with the plane, an explanation, etc. My "normal brake noise" after installation of new brakes & rotors ended up being a mis-installed wheel fairing. Go with your gut instincts.
* Know where to go to get answers. The Grumman gang mailing list is an excellent resource and monitored by some very savvy A&P's. The folks at FletchAir, and this site are all good references.
* Learn from your experiences. I know it's kinda obvious, but it needs to be said. Adding a fuel line pressurization check to my pre-flight checklist, for example.

Well, I hope that this story has been helpful. Take care and safe and happy flying!

--Mike

== The Rest of the Story ==

First: [[The_Annual_Inspection | The Annual Inspection]]

Previous: [[The Replies]]

The Replies

2008-08-14T14:05:45Z

Mboyd: /* Introduction */

== Introduction ==

This is part two (2) of a three (3) part article about Mike (and his '76 AA5A).

# [[The_Annual_Inspection | The Annual Inspection]]
# The Replies
# [[What_I%27ve_Learned | What I've Learned]]

== Part 2: Replies ==

Needless to say, the general consensus was that, while this may not be uncommon, I should attempt to find a shop that better meets my expectations. I received a number of responses with specific mechanic recommendations, and expressing their sympathy. I did not want to reproduce all of them here, but I do appreciate them.

Since the original posting, I have found another shop. Below are excerpts of some of the responses that helped me with that decision. (If you wish for me to remove your response for any reason, please let me know):

<blockquote>
Andy:
There are about 6 or 7 true Grumman gurus in the country and if you don't go to one of them you are pretty much going to be in charge of quality control....my solution is to work with the mechanics as much as I can during the inspection, accept whatever comes out so long as the paper work is correct and get a guru to do the inspection every few cycles.
</blockquote>

<blockquote>
Ed:
...You don't necessarily need a "guru" to do a good job. I'd rather have an honest, hardworking, meticulous A&P/AI that has limited Grumman experience work on my plane...If you have a good idea about the "special" areas to look out for (for example, SAIB on the tail bulkheads/stiffeners, Front gear service, delamination, aileron bearing wear, fuel tank leaks, corrosion on the main wing spar as viewed from the landing gear root area and also from the seat area, torque tube condition, slight lifting of cowling doors in flight, baffle/cooling dynamics, oil cooler mount cracking, throttle linkage integrity, and I am sure there are others I am missing) and tune your mechanic in to them then you're just about covered. After all, these planes are much easier (as in not harder) to figure out and maintain than a Cessna or Piper because they are so much simpler.
</blockquote>

<blockquote>
Steve:
I think you did all the right things in trying to be there for the annual. I think we all would fly and feel safer if we could be at those once a year events. You should have a copy of the maintenance manual with you at all times at an annual. Insist that the A&P follow it as close as possible and practical. The sqwaks you mentioned should never have happened.
</blockquote>

And, of course, there were many people that included comments like the following from Dave:

<blockquote>
I believe there is nobody better than [http://www.bondline.org/index.php/User:Bob_Steward Bob Steward] [or Cliff, Barry, Ron, etc.], both in knowledge and performance. I feel like I owe him a couple of kilobucks just for the knowledge gained and pain avoided from reading his posts and personal replies.
</blockquote>

(Just so you Guru's out there know that the rest of us that are just learning about these fine airplanes appreciate your, sometimes often repeated, advice and understanding!)

== The Rest of the Story ==

Previous: [[The_Annual_Inspection | The Annual Inspection]]

Last: [[What I've Learned]]

The Annual Inspection

2008-08-14T14:05:22Z

Mboyd: /* Introduction */

== Introduction ==

This is part one (1) of a three (3) part article about Mike (and his '76 AA5A).

# The Annual Inspection
# [[The Replies]]
# [[What I've Learned]]

== Part 1: The Annual Inspection ==

My Cheetah is the first airplane I've owned and we just went through our first annual together. I thought I'd share my experience and I'm also looking for some "sage advice" on what I should expect in an airplanes condition after it has completed an annual. I have found a number of problems since the airplane was returned to service by the shop (which came recommended by a number of individuals as one that knows Grummans...more on that below).

In addition to the basic annual, my squawk list included

* A throttle cable that was starting to get stiff
* A check of the charging system since a battery recently died (it was unknown age and was a really tired battery)
* Replacement of the aileron bearings/bushings as part of the 100 hour AD (recommended from previous AD compliance)
* Upgrading to the Boom Beam HID landing light (a x-mas gift from my wife - ain't she great).
* I had also told them I wanted the wobble check done since it had been over 500 hours since the top overhaul.

I had taken off 3 days from work in order to "owner assist" (mostly just help with the access panels and watch and learn).

On the first day of the annual, my skills with a Philips head screwdriver served me well as I removed most of the access panels, the wing tips and, with help, the cowl while the A&P spent a fair amount of the time looking at the HID light STC instructions and doing other prep work. We then went to work on the landing gear, finding that new brakes and discs were needed, cleaning and repacking the bearings. I'm thinking at this point that every airplane owner should definitely do this.

Day two was where it got interesting. Brake parts were on back order and most progress seemed to grind to a halt. The A&P decided that the tasks for the day were to install the HID landing light harness/control and replace the wind-sheared ELT antenna. Since the ELT antenna sits partially inside the vertical fin, the A&P decided he'd have to drill out the pop rivets that hold it to the bottom mounting. Since there are screws at the back of the fin and drilling out all those rivets sounded excessive, I asked if he would call Fletchair and see if there was a trick to this. He declined. Of course, after drilling out the rivets and lifting the fin off of the mount he found the clips that would have allowed removal by just removing the screws and sliding forward a few inches (yes *I* later looked this up in *their* copy of the maintenance manual - 53-0 p202). This, along with a prior incident explaining to them how the aileron AD was supposed to be done (Thanks Bob Steward & Barry), and I start to wonder about the "Grumman experience" of this shop.

Since parts were on back order, I went back to my job for a couple days and did not show back up at the shop until the day the parts were supposed to arrive. When I got there, I found that they had "done the rest" of the inspection and replaced most of the access covers and the lower cowl. So much for learning the rest of that process. All that was left was to finish the brake work and install the throttle cable. I was told that they had another plane coming in and needed to get mine wrapped up. So, the A&P finished the work (brakes and throttle cable) and I reinstalled the wheel fairings. I asked about the results of the wobble check and they said they didn't have the fixture but would order one if I wanted to reschedule another appointment. Hmm ... I've only had this scheduled with them for over a month and I specifically asked about this check ... oh well.

In hindsight I wish I had been there the entire time my plane was at the shop. After the A&P approved the plane for return to service, I found the following squawks that did not exist prior to the annual:

* The elevator would stick at about "neutral" - the problem was a interference by a mis-positioned throttle cable clamp.
* The elevator would make a noise when full left aileron was applied - A scat tube had moved into the control path.
* The flap fuse was blown and replacement caused immediate fuse failure - A&P said he checked the flaps and they were fine, but the limit switches may now be out of adjustment and the mechanism was jammed in the up position.
* The right brake intermittently loses effectiveness - Cured by bleeding the brakes.
* The wheels or brakes make rubbing noises as if a brake is sticking a little and the disc is warped. - This turned out to be a bent wheel fairing bracket. Fixed by my *new* shop.
* Fuel was leaking out of the carburetor return hose fitting @ ~4gph(1) They rechecked and tightened the fitting.
* My Nav2 radio no longer worked – New mechanic found that the plug had been knocked loose. Now fixed.
* Trim around the rear seat belt mounts had been broken (yeah, I know a nit pick and brittle plastic - guess I'll try that MEK and dissolved plastic trick I've been reading about. Of course the guys that replaced all the side window plastic a year earlier managed to do it without breaking the plastic)
* The updated W&B, required by the STC, was not placed in the plane (only copy was in their file).

This, unfortunately, was discovered in-flight by my fuel totalizer which was showing an unusual 13GPH consumption rate for my HC Cheetah. Looking inside with the electric pump on, there was an obvious stream (fountain?) of 100LL coming from the fitting. I have since modified my pre-flight checklist to include pressurizing the fuel system before the external walkaround and to check for fuel leak/smell around the cowl.

Now, I understand that my Cheetah's 30th birthday is this year and I would expect that things could potentially fail just after an annual. And I know that problems are why we regularly practice emergency procedures. But to have such a large number, and specifically items that they should have inspected or they touched during the course of their work, be problems immediately after the annual seems to be to be outside the range of normal coincidence. I have since received a copy of the checklist they use for annual inspections and have tried to compare it to the one in the maintenance manual. The one they use is a general checklist and so it includes items not on our planes (such as retractable landing gear checks) but does not include items specific to our cats (like skin bonding issues, canopy issues, etc.). And items on their checklist, like "Flight controls free and correct", do not appear to have been performed after all work was completed. I've founds checks in the inspection checklist in the Grumman Maintenance Manual that should have found all the above problems if done in an appropriate sequence.

So I'm now a little concerned that this annual was not done to the level of detail that I would expect from an inspection designed to verify the operational safety of an aircraft. To their credit, they have been good at working with me to fix the issues.

But like I said, I'm kind of new to this process so I'd like to hear from some of you veteran owners and mechanics out there. On a scale of "Oh, stop your whining" to "Go quickly and find another shop," where do you think this experience belongs?

== The Rest of the Story ==

Next: [[The Replies]]

Last: [[What_I%27ve_Learned | What I've Learned]]

Inspection Horror Stories

2008-08-14T14:04:49Z

Mboyd: /* A First Time Owners First Annual */

Post your story about an annual or a pre-purchase gone horribly wrong, so that others can learn from your experience and hopefully avoid the same pitfalls in the future.

The names of the shops, mechanics, owners and the N numbers need not be posted, to avoid embarrassment and to encourage more people to share their stories.

== A First Time Owners First Annual ==
I originally submitted this "story" as a number of posts to the Grumman Gang mailing list. I am including the original post (with some updates) replies, and some lessons learned here in the hopes that it helps other new aircraft owners. Thanks to the many gang members who replied, I have learned a lot from this experience!

---Mike (and his '76 AA5A)

[[The Annual Inspection]]

[[The Replies]]

[[What I've Learned]]

== Story #2 ==

Engine Baffles

2008-03-21T14:26:49Z

Mboyd: /* Finding Problems */

The engine baffles are critical to proper operation of the engine. They provide the sides for the box that holds the cooling air, and they also direct the air around the cylinder fins to minimize hot spots.

Its very common to see the metal portion of the baffles cracked and fretted from vibration, and to see the rubber seals hardened from heat and age, missing sections and replaced with the wrong types of material. The orange silicone rubber is the most popular replacement material, and its not really suitable for the job.

The rubber baffle seal needs to be thin and flexible, and it should have some fiber reinforcement to prevent tearing. The orange silicone rubber is too thick (1/8"), has no reinforcement, and tears easily.

When installing a lightweight starter such as the Sky-Tec, the front metal baffles on the 75 Traveler and all Cheetahs and Tigers must be trimmed to clear the different contour of the starter motor and solenoid.

Here are some examples of the trimming:

[[Image:Center-trim.jpg]]

[[Image:LH-Skytec.jpg]]

This is a seal I added to decrease the air leakage around the starter.

[[Image:Skytec-seal.jpg]]

Also check all of the baffle attach points. This AA5B broken bracket was hard to see, but was obviously not doing it's job. It is attached to the baffles by the oil cooler and held by the upper left engine mount bolt. A previous repair was less than effective. New brackets are available at Fletchair.

[[Image:Broken-baffle-bracket.JPG]]

==Cheetah Baffles - Part of my Hunt for High Oil Temperatures==
I have a Cheetah that suffered from higher oil temperatures than I'm comfortable with (CHT's look OK) during the warmest summer months. Everything has been done to this engine to make it run warm (High Compression mod, LASAR system) so this is not a big surprise. But hearing that people fly these machines in Arizona in the summer and the fact that I'm a bit of a perfectionist...I wanted to see if there is anything I could do to lower the temps.

In the course of chasing down the issue, (besides checking the oil cooler, vernatherm valve, and other system components) the old and ratty baffle seals were replaced under the supervision of one of the most Grumman knowledgeable shops around. After the seals were replaced, the following summer my temperatures were actually worse than the previous year. And thus began my education in the proper fit of baffle seals...

===Finding Problems===
I started by simply taking a flashlight and looking into the cooling air intakes in the nose bowl. I found several places where the seals did not sit flush against the cowl. In one location the seal bowed enough to create a quarter sized hole. This occurred because in the replacement of the seals, the multiple separate pieces of seal material were replaced with a few single longer strips of seal material that would buckle when pressed against the cowl where they were supposed to seal. Where the seals along the back and sides overlapped, they were attached together in such a way as to pull them away from the cowl. So, I removed these attachments and determined where to cut slits in the seal material so it would sit flush.

I then started looking around the nose bowl seals and found a number of locations where the seal fit was as poor as the seals against the cowl doors. I had to pull the cowl and hold the nose bowl in position as best I could (by holding it relative to the spinner/prop just as it looked when the cowl was attached) and inspect the seal fit. I used a marker to mark the locations where the seal did not fit well and made a number of additional slits in the ribbons of seal material. Often these slits were made where the contours of the cowl or nose bowl change. The seal near the landing light needed to be trimmed to fit the contour of the landing light recess in the nose bowl. There was also a location near the alternator where a longer strip of seal material was needed to close a hole caused by the additional distance between the baffle and the nose bowl in that area.

After 20 or more new slits in the baffle seal material and a new piece near the alternator, I put things back together and used a combination of drop lights and flashlights to check how well the seals were seating. Everything looked good, so I reassembled the cowl, checked the baffles one more time, and waited for the warm summer days to return for the tests.

===Test Flight===
Well, summer returned and I went on a test flight. The temps were lower...but only back to the point they were prior to replacing the seals. So, I continued my search. Off came the cowl and nose bowl and I found the seal around the starter (a location Bob mentioned above) was not that tight in spots and completely missing along the top of the starter (between the starter and the engine case) in what would equate to about a 1" x 3" hole. So, I constructed and installed a seal to close the hole. I also replaced the seal around the pipe that provides air to the muffler shroud as I determined the seal material there was the original and in bad shape. I then put everything back together and and performed a couple test flights. Things were looking better, but when the high temps of July and August hit, the oil temps wee still a bit high.

===Gathering Data===
[[Image:Manometer.JPG|thumb|100px|right|Manometer]]Stumped, I decided to try collecting some figures on the cooling. I constructed a simple water manometer to determine the pressure differential between the high pressure and low pressure side of the baffles. After some searching around the internet, I found that for effective cooling you need a pressure difference of at least 6" of water. We ran the tubing ends of the manometer from the cockpit out the canopy and in thru the oil door with one tube on each side of the baffle in the cowl. In flight we were able to determine that in cruise around 120 mph IAS the pressure difference was right around 6" of water. In a 100 mph IAS climb, the pressure dropped to around 5". So, the numbers indicated that I still had some issues as I was just barely coming into an acceptable cooling pressure range in cruise.

===The latest (and hopefully last) find===
So, my A&P (who had been overseeing my work all along) and I tried to find any other possible problems. After a bunch of snooping around with flashlights and inspection mirrors, my A&P was able to find another hole hiding in the seals. This hole was located just above the airbox and was caused by the fact that the standard width of the seal material sold in rolls is not wide enough to close a gap in that area. So, I obtained a larger piece of seal material (around 4.5" wide, if memory serves), off came the cowl and nose bowl again, and replaced the pieces that were too short.

===Pictures of the Results===
Below are several pictures of my baffle seals after the changes. Most of the slits you see were added as part of my attempts to improve the fit/seal. Sorry, I didn't take any before pictures, maybe I'll remember next time.
[[Image:UpperLeftSeals11u.JPG|thumb|200px|left]]
[[Image:UpperRightSeals11u.JPG|thumb|200px|none]]
[[Image:LowerSeals11u.JPG|thumb|200px|left]]
[[Image:LowerRightSeals11u.JPG|thumb|200px|none]]

===Conclusion (sort of)===
Of course, by the time we found and fixed this last issue, the hot summer temperatures had given way to cooler ones of fall. The oil temperatures have looked good since the last fix, but I guess I won't know for sure if the problem is resolved until summer returns again. I'll probably try the manometer again to see what it says...when my mechanic and I get a chance. I'll keep you posted. In the meantime, I hope this information helps if you have a Cheetah experiencing similar issues.

One last note. I was supplied the silicone type baffle seal material by the shop where the seals were initially replaced. I've found that this material isn't necessarily the best for seals as it is rather thick and does not "set" (retain a curved form) so you have to wrestle with it and be careful of the fit anytime you need to close the cowl or install the nose bowl.

Engine Baffles

2008-03-21T14:20:21Z

Mboyd: /* Gathering Data */

The engine baffles are critical to proper operation of the engine. They provide the sides for the box that holds the cooling air, and they also direct the air around the cylinder fins to minimize hot spots.

Its very common to see the metal portion of the baffles cracked and fretted from vibration, and to see the rubber seals hardened from heat and age, missing sections and replaced with the wrong types of material. The orange silicone rubber is the most popular replacement material, and its not really suitable for the job.

The rubber baffle seal needs to be thin and flexible, and it should have some fiber reinforcement to prevent tearing. The orange silicone rubber is too thick (1/8"), has no reinforcement, and tears easily.

When installing a lightweight starter such as the Sky-Tec, the front metal baffles on the 75 Traveler and all Cheetahs and Tigers must be trimmed to clear the different contour of the starter motor and solenoid.

Here are some examples of the trimming:

[[Image:Center-trim.jpg]]

[[Image:LH-Skytec.jpg]]

This is a seal I added to decrease the air leakage around the starter.

[[Image:Skytec-seal.jpg]]

Also check all of the baffle attach points. This AA5B broken bracket was hard to see, but was obviously not doing it's job. It is attached to the baffles by the oil cooler and held by the upper left engine mount bolt. A previous repair was less than effective. New brackets are available at Fletchair.

[[Image:Broken-baffle-bracket.JPG]]

==Cheetah Baffles - Part of my Hunt for High Oil Temperatures==
I have a Cheetah that suffered from higher oil temperatures than I'm comfortable with (CHT's look OK) during the warmest summer months. Everything has been done to this engine to make it run warm (High Compression mod, LASAR system) so this is not a big surprise. But hearing that people fly these machines in Arizona in the summer and the fact that I'm a bit of a perfectionist...I wanted to see if there is anything I could do to lower the temps.

In the course of chasing down the issue, (besides checking the oil cooler, vernatherm valve, and other system components) the old and ratty baffle seals were replaced under the supervision of one of the most Grumman knowledgeable shops around. After the seals were replaced, the following summer my temperatures were actually worse than the previous year. And thus began my education in the proper fit of baffle seals...

===Finding Problems===
I started by simply taking a flashlight and looking into the cooling air intakes in the nose bowl. I found several places where the seals did not sit flush against the cowl. In one location the seal bowed enough to create a quarter sized hole. This occurred because in the replacement of the seals, the multiple separate pieces of seal material were replaced with a few single longer strips of seal material that would buckle when pressed against the cowl where they were supposed to seal. Where the seals along the back and sides overlapped, they were attached together in such a way as to pull them away from the cowl. So, I removed these attachments and determined where to cut slits in the seal material so it would sit flush.

I then started looking around the nose bowl seals and found a number of locations where the seal fit was as poor as the seals against the cowl doors. I had to pull the cowl and hold the nose bowl in position as best I could (by holding it relative to the spinner/prop just as it looked when the cowl was attached) and inspect the seal fit. I used a marker to mark the locations where the seal did not fit well and made a number of additional slits in the ribbons of seal material. Often these slits were made where the contours of the cowl or nose bowl change. There was also a location near the alternator where a longer strip of seal material was needed to close a hole caused by the additional distance between the baffle and the nose bowl in that area.

After 20 or more new slits in the baffle seal material and a new piece near the alternator, I put things back together and used a combination of drop lights and flashlights to check how well the seals were seating. Everything looked good, so I reassembled the cowl, checked the baffles one more time, and waited for the warm summer days to return for the tests.

===Test Flight===
Well, summer returned and I went on a test flight. The temps were lower...but only back to the point they were prior to replacing the seals. So, I continued my search. Off came the cowl and nose bowl and I found the seal around the starter (a location Bob mentioned above) was not that tight in spots and completely missing along the top of the starter (between the starter and the engine case) in what would equate to about a 1" x 3" hole. So, I constructed and installed a seal to close the hole. I also replaced the seal around the pipe that provides air to the muffler shroud as I determined the seal material there was the original and in bad shape. I then put everything back together and and performed a couple test flights. Things were looking better, but when the high temps of July and August hit, the oil temps wee still a bit high.

===Gathering Data===
[[Image:Manometer.JPG|thumb|100px|right|Manometer]]Stumped, I decided to try collecting some figures on the cooling. I constructed a simple water manometer to determine the pressure differential between the high pressure and low pressure side of the baffles. After some searching around the internet, I found that for effective cooling you need a pressure difference of at least 6" of water. We ran the tubing ends of the manometer from the cockpit out the canopy and in thru the oil door with one tube on each side of the baffle in the cowl. In flight we were able to determine that in cruise around 120 mph IAS the pressure difference was right around 6" of water. In a 100 mph IAS climb, the pressure dropped to around 5". So, the numbers indicated that I still had some issues as I was just barely coming into an acceptable cooling pressure range in cruise.

===The latest (and hopefully last) find===
So, my A&P (who had been overseeing my work all along) and I tried to find any other possible problems. After a bunch of snooping around with flashlights and inspection mirrors, my A&P was able to find another hole hiding in the seals. This hole was located just above the airbox and was caused by the fact that the standard width of the seal material sold in rolls is not wide enough to close a gap in that area. So, I obtained a larger piece of seal material (around 4.5" wide, if memory serves), off came the cowl and nose bowl again, and replaced the pieces that were too short.

===Pictures of the Results===
Below are several pictures of my baffle seals after the changes. Most of the slits you see were added as part of my attempts to improve the fit/seal. Sorry, I didn't take any before pictures, maybe I'll remember next time.
[[Image:UpperLeftSeals11u.JPG|thumb|200px|left]]
[[Image:UpperRightSeals11u.JPG|thumb|200px|none]]
[[Image:LowerSeals11u.JPG|thumb|200px|left]]
[[Image:LowerRightSeals11u.JPG|thumb|200px|none]]

===Conclusion (sort of)===
Of course, by the time we found and fixed this last issue, the hot summer temperatures had given way to cooler ones of fall. The oil temperatures have looked good since the last fix, but I guess I won't know for sure if the problem is resolved until summer returns again. I'll probably try the manometer again to see what it says...when my mechanic and I get a chance. I'll keep you posted. In the meantime, I hope this information helps if you have a Cheetah experiencing similar issues.

One last note. I was supplied the silicone type baffle seal material by the shop where the seals were initially replaced. I've found that this material isn't necessarily the best for seals as it is rather thick and does not "set" (retain a curved form) so you have to wrestle with it and be careful of the fit anytime you need to close the cowl or install the nose bowl.

File:Manometer.JPG

2008-03-21T14:17:35Z

Mboyd: A simple water manometer.

A simple water manometer.

Engine Baffles

2008-03-21T14:16:39Z

Mboyd: /* Conclusion (sort of) */

The engine baffles are critical to proper operation of the engine. They provide the sides for the box that holds the cooling air, and they also direct the air around the cylinder fins to minimize hot spots.

Its very common to see the metal portion of the baffles cracked and fretted from vibration, and to see the rubber seals hardened from heat and age, missing sections and replaced with the wrong types of material. The orange silicone rubber is the most popular replacement material, and its not really suitable for the job.

The rubber baffle seal needs to be thin and flexible, and it should have some fiber reinforcement to prevent tearing. The orange silicone rubber is too thick (1/8"), has no reinforcement, and tears easily.

When installing a lightweight starter such as the Sky-Tec, the front metal baffles on the 75 Traveler and all Cheetahs and Tigers must be trimmed to clear the different contour of the starter motor and solenoid.

Here are some examples of the trimming:

[[Image:Center-trim.jpg]]

[[Image:LH-Skytec.jpg]]

This is a seal I added to decrease the air leakage around the starter.

[[Image:Skytec-seal.jpg]]

Also check all of the baffle attach points. This AA5B broken bracket was hard to see, but was obviously not doing it's job. It is attached to the baffles by the oil cooler and held by the upper left engine mount bolt. A previous repair was less than effective. New brackets are available at Fletchair.

[[Image:Broken-baffle-bracket.JPG]]

==Cheetah Baffles - Part of my Hunt for High Oil Temperatures==
I have a Cheetah that suffered from higher oil temperatures than I'm comfortable with (CHT's look OK) during the warmest summer months. Everything has been done to this engine to make it run warm (High Compression mod, LASAR system) so this is not a big surprise. But hearing that people fly these machines in Arizona in the summer and the fact that I'm a bit of a perfectionist...I wanted to see if there is anything I could do to lower the temps.

In the course of chasing down the issue, (besides checking the oil cooler, vernatherm valve, and other system components) the old and ratty baffle seals were replaced under the supervision of one of the most Grumman knowledgeable shops around. After the seals were replaced, the following summer my temperatures were actually worse than the previous year. And thus began my education in the proper fit of baffle seals...

===Finding Problems===
I started by simply taking a flashlight and looking into the cooling air intakes in the nose bowl. I found several places where the seals did not sit flush against the cowl. In one location the seal bowed enough to create a quarter sized hole. This occurred because in the replacement of the seals, the multiple separate pieces of seal material were replaced with a few single longer strips of seal material that would buckle when pressed against the cowl where they were supposed to seal. Where the seals along the back and sides overlapped, they were attached together in such a way as to pull them away from the cowl. So, I removed these attachments and determined where to cut slits in the seal material so it would sit flush.

I then started looking around the nose bowl seals and found a number of locations where the seal fit was as poor as the seals against the cowl doors. I had to pull the cowl and hold the nose bowl in position as best I could (by holding it relative to the spinner/prop just as it looked when the cowl was attached) and inspect the seal fit. I used a marker to mark the locations where the seal did not fit well and made a number of additional slits in the ribbons of seal material. Often these slits were made where the contours of the cowl or nose bowl change. There was also a location near the alternator where a longer strip of seal material was needed to close a hole caused by the additional distance between the baffle and the nose bowl in that area.

After 20 or more new slits in the baffle seal material and a new piece near the alternator, I put things back together and used a combination of drop lights and flashlights to check how well the seals were seating. Everything looked good, so I reassembled the cowl, checked the baffles one more time, and waited for the warm summer days to return for the tests.

===Test Flight===
Well, summer returned and I went on a test flight. The temps were lower...but only back to the point they were prior to replacing the seals. So, I continued my search. Off came the cowl and nose bowl and I found the seal around the starter (a location Bob mentioned above) was not that tight in spots and completely missing along the top of the starter (between the starter and the engine case) in what would equate to about a 1" x 3" hole. So, I constructed and installed a seal to close the hole. I also replaced the seal around the pipe that provides air to the muffler shroud as I determined the seal material there was the original and in bad shape. I then put everything back together and and performed a couple test flights. Things were looking better, but when the high temps of July and August hit, the oil temps wee still a bit high.

===Gathering Data===
Stumped, I decided to try collecting some figures on the cooling. I constructed a simple water manometer to determine the pressure differential between the high pressure and low pressure side of the baffles. After some searching around the internet, I found that for effective cooling you need a pressure difference of at least 6" of water. We ran the tubing ends of the manometer from the cockpit out the canopy and in thru the oil door with one tube on each side of the baffle in the cowl. In flight we were able to determine that in cruise around 120 mph IAS the pressure difference was right around 6" of water. In a 100 mph IAS climb, the pressure dropped to around 5". So, the numbers indicated that I still had some issues as I was just barely coming into an acceptable cooling pressure range in cruise.

===The latest (and hopefully last) find===
So, my A&P (who had been overseeing my work all along) and I tried to find any other possible problems. After a bunch of snooping around with flashlights and inspection mirrors, my A&P was able to find another hole hiding in the seals. This hole was located just above the airbox and was caused by the fact that the standard width of the seal material sold in rolls is not wide enough to close a gap in that area. So, I obtained a larger piece of seal material (around 4.5" wide, if memory serves), off came the cowl and nose bowl again, and replaced the pieces that were too short.

===Pictures of the Results===
Below are several pictures of my baffle seals after the changes. Most of the slits you see were added as part of my attempts to improve the fit/seal. Sorry, I didn't take any before pictures, maybe I'll remember next time.
[[Image:UpperLeftSeals11u.JPG|thumb|200px|left]]
[[Image:UpperRightSeals11u.JPG|thumb|200px|none]]
[[Image:LowerSeals11u.JPG|thumb|200px|left]]
[[Image:LowerRightSeals11u.JPG|thumb|200px|none]]

===Conclusion (sort of)===
Of course, by the time we found and fixed this last issue, the hot summer temperatures had given way to cooler ones of fall. The oil temperatures have looked good since the last fix, but I guess I won't know for sure if the problem is resolved until summer returns again. I'll probably try the manometer again to see what it says...when my mechanic and I get a chance. I'll keep you posted. In the meantime, I hope this information helps if you have a Cheetah experiencing similar issues.

One last note. I was supplied the silicone type baffle seal material by the shop where the seals were initially replaced. I've found that this material isn't necessarily the best for seals as it is rather thick and does not "set" (retain a curved form) so you have to wrestle with it and be careful of the fit anytime you need to close the cowl or install the nose bowl.

Engine Baffles

2008-03-21T14:13:26Z

Mboyd: /* Pictures of the Results */

The engine baffles are critical to proper operation of the engine. They provide the sides for the box that holds the cooling air, and they also direct the air around the cylinder fins to minimize hot spots.

Its very common to see the metal portion of the baffles cracked and fretted from vibration, and to see the rubber seals hardened from heat and age, missing sections and replaced with the wrong types of material. The orange silicone rubber is the most popular replacement material, and its not really suitable for the job.

The rubber baffle seal needs to be thin and flexible, and it should have some fiber reinforcement to prevent tearing. The orange silicone rubber is too thick (1/8"), has no reinforcement, and tears easily.

When installing a lightweight starter such as the Sky-Tec, the front metal baffles on the 75 Traveler and all Cheetahs and Tigers must be trimmed to clear the different contour of the starter motor and solenoid.

Here are some examples of the trimming:

[[Image:Center-trim.jpg]]

[[Image:LH-Skytec.jpg]]

This is a seal I added to decrease the air leakage around the starter.

[[Image:Skytec-seal.jpg]]

Also check all of the baffle attach points. This AA5B broken bracket was hard to see, but was obviously not doing it's job. It is attached to the baffles by the oil cooler and held by the upper left engine mount bolt. A previous repair was less than effective. New brackets are available at Fletchair.

[[Image:Broken-baffle-bracket.JPG]]

==Cheetah Baffles - Part of my Hunt for High Oil Temperatures==
I have a Cheetah that suffered from higher oil temperatures than I'm comfortable with (CHT's look OK) during the warmest summer months. Everything has been done to this engine to make it run warm (High Compression mod, LASAR system) so this is not a big surprise. But hearing that people fly these machines in Arizona in the summer and the fact that I'm a bit of a perfectionist...I wanted to see if there is anything I could do to lower the temps.

In the course of chasing down the issue, (besides checking the oil cooler, vernatherm valve, and other system components) the old and ratty baffle seals were replaced under the supervision of one of the most Grumman knowledgeable shops around. After the seals were replaced, the following summer my temperatures were actually worse than the previous year. And thus began my education in the proper fit of baffle seals...

===Finding Problems===
I started by simply taking a flashlight and looking into the cooling air intakes in the nose bowl. I found several places where the seals did not sit flush against the cowl. In one location the seal bowed enough to create a quarter sized hole. This occurred because in the replacement of the seals, the multiple separate pieces of seal material were replaced with a few single longer strips of seal material that would buckle when pressed against the cowl where they were supposed to seal. Where the seals along the back and sides overlapped, they were attached together in such a way as to pull them away from the cowl. So, I removed these attachments and determined where to cut slits in the seal material so it would sit flush.

I then started looking around the nose bowl seals and found a number of locations where the seal fit was as poor as the seals against the cowl doors. I had to pull the cowl and hold the nose bowl in position as best I could (by holding it relative to the spinner/prop just as it looked when the cowl was attached) and inspect the seal fit. I used a marker to mark the locations where the seal did not fit well and made a number of additional slits in the ribbons of seal material. Often these slits were made where the contours of the cowl or nose bowl change. There was also a location near the alternator where a longer strip of seal material was needed to close a hole caused by the additional distance between the baffle and the nose bowl in that area.

After 20 or more new slits in the baffle seal material and a new piece near the alternator, I put things back together and used a combination of drop lights and flashlights to check how well the seals were seating. Everything looked good, so I reassembled the cowl, checked the baffles one more time, and waited for the warm summer days to return for the tests.

===Test Flight===
Well, summer returned and I went on a test flight. The temps were lower...but only back to the point they were prior to replacing the seals. So, I continued my search. Off came the cowl and nose bowl and I found the seal around the starter (a location Bob mentioned above) was not that tight in spots and completely missing along the top of the starter (between the starter and the engine case) in what would equate to about a 1" x 3" hole. So, I constructed and installed a seal to close the hole. I also replaced the seal around the pipe that provides air to the muffler shroud as I determined the seal material there was the original and in bad shape. I then put everything back together and and performed a couple test flights. Things were looking better, but when the high temps of July and August hit, the oil temps wee still a bit high.

===Gathering Data===
Stumped, I decided to try collecting some figures on the cooling. I constructed a simple water manometer to determine the pressure differential between the high pressure and low pressure side of the baffles. After some searching around the internet, I found that for effective cooling you need a pressure difference of at least 6" of water. We ran the tubing ends of the manometer from the cockpit out the canopy and in thru the oil door with one tube on each side of the baffle in the cowl. In flight we were able to determine that in cruise around 120 mph IAS the pressure difference was right around 6" of water. In a 100 mph IAS climb, the pressure dropped to around 5". So, the numbers indicated that I still had some issues as I was just barely coming into an acceptable cooling pressure range in cruise.

===The latest (and hopefully last) find===
So, my A&P (who had been overseeing my work all along) and I tried to find any other possible problems. After a bunch of snooping around with flashlights and inspection mirrors, my A&P was able to find another hole hiding in the seals. This hole was located just above the airbox and was caused by the fact that the standard width of the seal material sold in rolls is not wide enough to close a gap in that area. So, I obtained a larger piece of seal material (around 4.5" wide, if memory serves), off came the cowl and nose bowl again, and replaced the pieces that were too short.

===Pictures of the Results===
Below are several pictures of my baffle seals after the changes. Most of the slits you see were added as part of my attempts to improve the fit/seal. Sorry, I didn't take any before pictures, maybe I'll remember next time.
[[Image:UpperLeftSeals11u.JPG|thumb|200px|left]]
[[Image:UpperRightSeals11u.JPG|thumb|200px|none]]
[[Image:LowerSeals11u.JPG|thumb|200px|left]]
[[Image:LowerRightSeals11u.JPG|thumb|200px|none]]

===Conclusion (sort of)===
Of course, by the time we found and fixed this issue, the hot summer temperatures had given way to cooler ones of fall. The oil temperatures have looked good since the last fix, but I guess I won't know for sure if the problem is resolved until summer returns again. I'll probably try the manometer again to see what it says...when my mechanic and I get a chance. I'll keep you posted. In the meantime, I hope this information helps if you have a Cheetah experiencing similar issues.

One last note. I was supplied the silicone type baffle seal material by the shop where the seals were initially replaced. I've found that this material isn't necessarily the best for seals as it is rather thick and does not "set" (retain a curved form) so you have to wrestle with it and be careful of the fit anytime you need to close the cowl or install the nose bowl.

Engine Baffles

2008-03-21T14:09:57Z

Mboyd: /* Finding Problems */

The engine baffles are critical to proper operation of the engine. They provide the sides for the box that holds the cooling air, and they also direct the air around the cylinder fins to minimize hot spots.

Its very common to see the metal portion of the baffles cracked and fretted from vibration, and to see the rubber seals hardened from heat and age, missing sections and replaced with the wrong types of material. The orange silicone rubber is the most popular replacement material, and its not really suitable for the job.

The rubber baffle seal needs to be thin and flexible, and it should have some fiber reinforcement to prevent tearing. The orange silicone rubber is too thick (1/8"), has no reinforcement, and tears easily.

When installing a lightweight starter such as the Sky-Tec, the front metal baffles on the 75 Traveler and all Cheetahs and Tigers must be trimmed to clear the different contour of the starter motor and solenoid.

Here are some examples of the trimming:

[[Image:Center-trim.jpg]]

[[Image:LH-Skytec.jpg]]

This is a seal I added to decrease the air leakage around the starter.

[[Image:Skytec-seal.jpg]]

Also check all of the baffle attach points. This AA5B broken bracket was hard to see, but was obviously not doing it's job. It is attached to the baffles by the oil cooler and held by the upper left engine mount bolt. A previous repair was less than effective. New brackets are available at Fletchair.

[[Image:Broken-baffle-bracket.JPG]]

==Cheetah Baffles - Part of my Hunt for High Oil Temperatures==
I have a Cheetah that suffered from higher oil temperatures than I'm comfortable with (CHT's look OK) during the warmest summer months. Everything has been done to this engine to make it run warm (High Compression mod, LASAR system) so this is not a big surprise. But hearing that people fly these machines in Arizona in the summer and the fact that I'm a bit of a perfectionist...I wanted to see if there is anything I could do to lower the temps.

In the course of chasing down the issue, (besides checking the oil cooler, vernatherm valve, and other system components) the old and ratty baffle seals were replaced under the supervision of one of the most Grumman knowledgeable shops around. After the seals were replaced, the following summer my temperatures were actually worse than the previous year. And thus began my education in the proper fit of baffle seals...

===Finding Problems===
I started by simply taking a flashlight and looking into the cooling air intakes in the nose bowl. I found several places where the seals did not sit flush against the cowl. In one location the seal bowed enough to create a quarter sized hole. This occurred because in the replacement of the seals, the multiple separate pieces of seal material were replaced with a few single longer strips of seal material that would buckle when pressed against the cowl where they were supposed to seal. Where the seals along the back and sides overlapped, they were attached together in such a way as to pull them away from the cowl. So, I removed these attachments and determined where to cut slits in the seal material so it would sit flush.

I then started looking around the nose bowl seals and found a number of locations where the seal fit was as poor as the seals against the cowl doors. I had to pull the cowl and hold the nose bowl in position as best I could (by holding it relative to the spinner/prop just as it looked when the cowl was attached) and inspect the seal fit. I used a marker to mark the locations where the seal did not fit well and made a number of additional slits in the ribbons of seal material. Often these slits were made where the contours of the cowl or nose bowl change. There was also a location near the alternator where a longer strip of seal material was needed to close a hole caused by the additional distance between the baffle and the nose bowl in that area.

After 20 or more new slits in the baffle seal material and a new piece near the alternator, I put things back together and used a combination of drop lights and flashlights to check how well the seals were seating. Everything looked good, so I reassembled the cowl, checked the baffles one more time, and waited for the warm summer days to return for the tests.

===Test Flight===
Well, summer returned and I went on a test flight. The temps were lower...but only back to the point they were prior to replacing the seals. So, I continued my search. Off came the cowl and nose bowl and I found the seal around the starter (a location Bob mentioned above) was not that tight in spots and completely missing along the top of the starter (between the starter and the engine case) in what would equate to about a 1" x 3" hole. So, I constructed and installed a seal to close the hole. I also replaced the seal around the pipe that provides air to the muffler shroud as I determined the seal material there was the original and in bad shape. I then put everything back together and and performed a couple test flights. Things were looking better, but when the high temps of July and August hit, the oil temps wee still a bit high.

===Gathering Data===
Stumped, I decided to try collecting some figures on the cooling. I constructed a simple water manometer to determine the pressure differential between the high pressure and low pressure side of the baffles. After some searching around the internet, I found that for effective cooling you need a pressure difference of at least 6" of water. We ran the tubing ends of the manometer from the cockpit out the canopy and in thru the oil door with one tube on each side of the baffle in the cowl. In flight we were able to determine that in cruise around 120 mph IAS the pressure difference was right around 6" of water. In a 100 mph IAS climb, the pressure dropped to around 5". So, the numbers indicated that I still had some issues as I was just barely coming into an acceptable cooling pressure range in cruise.

===The latest (and hopefully last) find===
So, my A&P (who had been overseeing my work all along) and I tried to find any other possible problems. After a bunch of snooping around with flashlights and inspection mirrors, my A&P was able to find another hole hiding in the seals. This hole was located just above the airbox and was caused by the fact that the standard width of the seal material sold in rolls is not wide enough to close a gap in that area. So, I obtained a larger piece of seal material (around 4.5" wide, if memory serves), off came the cowl and nose bowl again, and replaced the pieces that were too short.

===Pictures of the Results===
Below are several pictures of my baffle seals after the changes. Sorry, I didn't take any before pictures, maybe I'll remember next time.
[[Image:UpperLeftSeals11u.JPG|thumb|200px|left]]
[[Image:UpperRightSeals11u.JPG|thumb|200px|none]]
[[Image:LowerSeals11u.JPG|thumb|200px|left]]
[[Image:LowerRightSeals11u.JPG|thumb|200px|none]]

===Conclusion (sort of)===
Of course, by the time we found and fixed this issue, the hot summer temperatures had given way to cooler ones of fall. The oil temperatures have looked good since the last fix, but I guess I won't know for sure if the problem is resolved until summer returns again. I'll probably try the manometer again to see what it says...when my mechanic and I get a chance. I'll keep you posted. In the meantime, I hope this information helps if you have a Cheetah experiencing similar issues.

One last note. I was supplied the silicone type baffle seal material by the shop where the seals were initially replaced. I've found that this material isn't necessarily the best for seals as it is rather thick and does not "set" (retain a curved form) so you have to wrestle with it and be careful of the fit anytime you need to close the cowl or install the nose bowl.

Engine Baffles

2008-03-21T01:22:32Z

Mboyd: /* Pictures of the Results */

The engine baffles are critical to proper operation of the engine. They provide the sides for the box that holds the cooling air, and they also direct the air around the cylinder fins to minimize hot spots.

Its very common to see the metal portion of the baffles cracked and fretted from vibration, and to see the rubber seals hardened from heat and age, missing sections and replaced with the wrong types of material. The orange silicone rubber is the most popular replacement material, and its not really suitable for the job.

The rubber baffle seal needs to be thin and flexible, and it should have some fiber reinforcement to prevent tearing. The orange silicone rubber is too thick (1/8"), has no reinforcement, and tears easily.

When installing a lightweight starter such as the Sky-Tec, the front metal baffles on the 75 Traveler and all Cheetahs and Tigers must be trimmed to clear the different contour of the starter motor and solenoid.

Here are some examples of the trimming:

[[Image:Center-trim.jpg]]

[[Image:LH-Skytec.jpg]]

This is a seal I added to decrease the air leakage around the starter.

[[Image:Skytec-seal.jpg]]

Also check all of the baffle attach points. This AA5B broken bracket was hard to see, but was obviously not doing it's job. It is attached to the baffles by the oil cooler and held by the upper left engine mount bolt. A previous repair was less than effective. New brackets are available at Fletchair.

[[Image:Broken-baffle-bracket.JPG]]

==Cheetah Baffles - Part of my Hunt for High Oil Temperatures==
I have a Cheetah that suffered from higher oil temperatures than I'm comfortable with (CHT's look OK) during the warmest summer months. Everything has been done to this engine to make it run warm (High Compression mod, LASAR system) so this is not a big surprise. But hearing that people fly these machines in Arizona in the summer and the fact that I'm a bit of a perfectionist...I wanted to see if there is anything I could do to lower the temps.

In the course of chasing down the issue, (besides checking the oil cooler, vernatherm valve, and other system components) the old and ratty baffle seals were replaced under the supervision of one of the most Grumman knowledgeable shops around. After the seals were replaced, the following summer my temperatures were actually worse than the previous year. And thus began my education in the proper fit of baffle seals...

===Finding Problems===
I started by simply taking a flashlight and looking into the cooling air intakes in the nose bowl. I found several places where the seals did not sit flush against the cowl. In one location the seal bowed enough to create a quarter sized hole. This occurred because in the replacement of the seals, the multiple separate pieces of seal material were replaced with a few single longer strips of seal material. Where the seals along the back and sides overlapped, they were attached together in such a way as to pull them away from the cowl. So, I removed these attachments and determined where to cut slits in the seal material so it would sit flush.

I then started looking around the nose bowl seals and found a number of locations where the seal fit was as poor as the seals against the cowl doors. I had to pull the cowl and hold the nose bowl in position as best I could (by holding it relative to the spinner/prop just as it looked when the cowl was attached) and inspect the seal fit. I used a marker to mark the locations where the seal did not fit well and made a number of additional slits in the ribbons of seal material. Often these slits were made where the contours of the cowl or nose bowl change. There was also a location near the alternator where a longer strip of seal material was needed to close a hole caused by the additional distance between the baffle and the nose bowl in that area.

After 20 or more new slits in the baffle seal material and a new piece near the alternator, I put things back together and used a combination of drop lights and flashlights to check how well the seals were seating. Everything looked good, so I reassembled the cowl, checked the baffles one more time, and waited for the warm summer days to return for the tests.

===Test Flight===
Well, summer returned and I went on a test flight. The temps were lower...but only back to the point they were prior to replacing the seals. So, I continued my search. Off came the cowl and nose bowl and I found the seal around the starter (a location Bob mentioned above) was not that tight in spots and completely missing along the top of the starter (between the starter and the engine case) in what would equate to about a 1" x 3" hole. So, I constructed and installed a seal to close the hole. I also replaced the seal around the pipe that provides air to the muffler shroud as I determined the seal material there was the original and in bad shape. I then put everything back together and and performed a couple test flights. Things were looking better, but when the high temps of July and August hit, the oil temps wee still a bit high.

===Gathering Data===
Stumped, I decided to try collecting some figures on the cooling. I constructed a simple water manometer to determine the pressure differential between the high pressure and low pressure side of the baffles. After some searching around the internet, I found that for effective cooling you need a pressure difference of at least 6" of water. We ran the tubing ends of the manometer from the cockpit out the canopy and in thru the oil door with one tube on each side of the baffle in the cowl. In flight we were able to determine that in cruise around 120 mph IAS the pressure difference was right around 6" of water. In a 100 mph IAS climb, the pressure dropped to around 5". So, the numbers indicated that I still had some issues as I was just barely coming into an acceptable cooling pressure range in cruise.

===The latest (and hopefully last) find===
So, my A&P (who had been overseeing my work all along) and I tried to find any other possible problems. After a bunch of snooping around with flashlights and inspection mirrors, my A&P was able to find another hole hiding in the seals. This hole was located just above the airbox and was caused by the fact that the standard width of the seal material sold in rolls is not wide enough to close a gap in that area. So, I obtained a larger piece of seal material (around 4.5" wide, if memory serves), off came the cowl and nose bowl again, and replaced the pieces that were too short.

===Pictures of the Results===
Below are several pictures of my baffle seals after the changes. Sorry, I didn't take any before pictures, maybe I'll remember next time.
[[Image:UpperLeftSeals11u.JPG|thumb|200px|left]]
[[Image:UpperRightSeals11u.JPG|thumb|200px|none]]
[[Image:LowerSeals11u.JPG|thumb|200px|left]]
[[Image:LowerRightSeals11u.JPG|thumb|200px|none]]

===Conclusion (sort of)===
Of course, by the time we found and fixed this issue, the hot summer temperatures had given way to cooler ones of fall. The oil temperatures have looked good since the last fix, but I guess I won't know for sure if the problem is resolved until summer returns again. I'll probably try the manometer again to see what it says...when my mechanic and I get a chance. I'll keep you posted. In the meantime, I hope this information helps if you have a Cheetah experiencing similar issues.

One last note. I was supplied the silicone type baffle seal material by the shop where the seals were initially replaced. I've found that this material isn't necessarily the best for seals as it is rather thick and does not "set" (retain a curved form) so you have to wrestle with it and be careful of the fit anytime you need to close the cowl or install the nose bowl.

Engine Baffles

2008-03-21T01:19:10Z

Mboyd: /* Pictures of the Results */

The engine baffles are critical to proper operation of the engine. They provide the sides for the box that holds the cooling air, and they also direct the air around the cylinder fins to minimize hot spots.

Its very common to see the metal portion of the baffles cracked and fretted from vibration, and to see the rubber seals hardened from heat and age, missing sections and replaced with the wrong types of material. The orange silicone rubber is the most popular replacement material, and its not really suitable for the job.

The rubber baffle seal needs to be thin and flexible, and it should have some fiber reinforcement to prevent tearing. The orange silicone rubber is too thick (1/8"), has no reinforcement, and tears easily.

When installing a lightweight starter such as the Sky-Tec, the front metal baffles on the 75 Traveler and all Cheetahs and Tigers must be trimmed to clear the different contour of the starter motor and solenoid.

Here are some examples of the trimming:

[[Image:Center-trim.jpg]]

[[Image:LH-Skytec.jpg]]

This is a seal I added to decrease the air leakage around the starter.

[[Image:Skytec-seal.jpg]]

Also check all of the baffle attach points. This AA5B broken bracket was hard to see, but was obviously not doing it's job. It is attached to the baffles by the oil cooler and held by the upper left engine mount bolt. A previous repair was less than effective. New brackets are available at Fletchair.

[[Image:Broken-baffle-bracket.JPG]]

==Cheetah Baffles - Part of my Hunt for High Oil Temperatures==
I have a Cheetah that suffered from higher oil temperatures than I'm comfortable with (CHT's look OK) during the warmest summer months. Everything has been done to this engine to make it run warm (High Compression mod, LASAR system) so this is not a big surprise. But hearing that people fly these machines in Arizona in the summer and the fact that I'm a bit of a perfectionist...I wanted to see if there is anything I could do to lower the temps.

In the course of chasing down the issue, (besides checking the oil cooler, vernatherm valve, and other system components) the old and ratty baffle seals were replaced under the supervision of one of the most Grumman knowledgeable shops around. After the seals were replaced, the following summer my temperatures were actually worse than the previous year. And thus began my education in the proper fit of baffle seals...

===Finding Problems===
I started by simply taking a flashlight and looking into the cooling air intakes in the nose bowl. I found several places where the seals did not sit flush against the cowl. In one location the seal bowed enough to create a quarter sized hole. This occurred because in the replacement of the seals, the multiple separate pieces of seal material were replaced with a few single longer strips of seal material. Where the seals along the back and sides overlapped, they were attached together in such a way as to pull them away from the cowl. So, I removed these attachments and determined where to cut slits in the seal material so it would sit flush.

I then started looking around the nose bowl seals and found a number of locations where the seal fit was as poor as the seals against the cowl doors. I had to pull the cowl and hold the nose bowl in position as best I could (by holding it relative to the spinner/prop just as it looked when the cowl was attached) and inspect the seal fit. I used a marker to mark the locations where the seal did not fit well and made a number of additional slits in the ribbons of seal material. Often these slits were made where the contours of the cowl or nose bowl change. There was also a location near the alternator where a longer strip of seal material was needed to close a hole caused by the additional distance between the baffle and the nose bowl in that area.

After 20 or more new slits in the baffle seal material and a new piece near the alternator, I put things back together and used a combination of drop lights and flashlights to check how well the seals were seating. Everything looked good, so I reassembled the cowl, checked the baffles one more time, and waited for the warm summer days to return for the tests.

===Test Flight===
Well, summer returned and I went on a test flight. The temps were lower...but only back to the point they were prior to replacing the seals. So, I continued my search. Off came the cowl and nose bowl and I found the seal around the starter (a location Bob mentioned above) was not that tight in spots and completely missing along the top of the starter (between the starter and the engine case) in what would equate to about a 1" x 3" hole. So, I constructed and installed a seal to close the hole. I also replaced the seal around the pipe that provides air to the muffler shroud as I determined the seal material there was the original and in bad shape. I then put everything back together and and performed a couple test flights. Things were looking better, but when the high temps of July and August hit, the oil temps wee still a bit high.

===Gathering Data===
Stumped, I decided to try collecting some figures on the cooling. I constructed a simple water manometer to determine the pressure differential between the high pressure and low pressure side of the baffles. After some searching around the internet, I found that for effective cooling you need a pressure difference of at least 6" of water. We ran the tubing ends of the manometer from the cockpit out the canopy and in thru the oil door with one tube on each side of the baffle in the cowl. In flight we were able to determine that in cruise around 120 mph IAS the pressure difference was right around 6" of water. In a 100 mph IAS climb, the pressure dropped to around 5". So, the numbers indicated that I still had some issues as I was just barely coming into an acceptable cooling pressure range in cruise.

===The latest (and hopefully last) find===
So, my A&P (who had been overseeing my work all along) and I tried to find any other possible problems. After a bunch of snooping around with flashlights and inspection mirrors, my A&P was able to find another hole hiding in the seals. This hole was located just above the airbox and was caused by the fact that the standard width of the seal material sold in rolls is not wide enough to close a gap in that area. So, I obtained a larger piece of seal material (around 4.5" wide, if memory serves), off came the cowl and nose bowl again, and replaced the pieces that were too short.

===Pictures of the Results===
Below are several pictures of my baffle seals after the changes. Sorry, I didn't take any before pictures, maybe I'll remember next time.
[[Image:UpperLeftSeals11u.jpg|thumb|100px|left]]
[[Image:UpperRightSeals11u.jpg|thumb|100px|none]]
[[Image:LowerSeals11u.jpg|thumb|100px|none]]
[[Image:LowerRightSeals11u.jpg|thumb|100px|none]]

===Conclusion (sort of)===
Of course, by the time we found and fixed this issue, the hot summer temperatures had given way to cooler ones of fall. The oil temperatures have looked good since the last fix, but I guess I won't know for sure if the problem is resolved until summer returns again. I'll probably try the manometer again to see what it says...when my mechanic and I get a chance. I'll keep you posted. In the meantime, I hope this information helps if you have a Cheetah experiencing similar issues.

One last note. I was supplied the silicone type baffle seal material by the shop where the seals were initially replaced. I've found that this material isn't necessarily the best for seals as it is rather thick and does not "set" (retain a curved form) so you have to wrestle with it and be careful of the fit anytime you need to close the cowl or install the nose bowl.

File:LowerRightSeals11u.JPG

2008-03-21T01:11:17Z

Mboyd: Lower right nosebowl baffle seals for Cheetah

Lower right nosebowl baffle seals for Cheetah

File:LowerSeals11u.JPG

2008-03-21T01:10:02Z

Mboyd: Lower nosebowl baffle seals on a Cheetah

Lower nosebowl baffle seals on a Cheetah

File:UpperRightSeals11u.JPG

2008-03-21T01:08:53Z

Mboyd: Upper right baffle seals on a Cheetah

Upper right baffle seals on a Cheetah

File:UpperLeftSeals11u.JPG

2008-03-21T01:07:43Z

Mboyd: Upper left baffle seals on a Cheetah

Upper left baffle seals on a Cheetah

Engine Baffles

2008-03-21T01:03:41Z

Mboyd:

The engine baffles are critical to proper operation of the engine. They provide the sides for the box that holds the cooling air, and they also direct the air around the cylinder fins to minimize hot spots.

Its very common to see the metal portion of the baffles cracked and fretted from vibration, and to see the rubber seals hardened from heat and age, missing sections and replaced with the wrong types of material. The orange silicone rubber is the most popular replacement material, and its not really suitable for the job.

The rubber baffle seal needs to be thin and flexible, and it should have some fiber reinforcement to prevent tearing. The orange silicone rubber is too thick (1/8"), has no reinforcement, and tears easily.

When installing a lightweight starter such as the Sky-Tec, the front metal baffles on the 75 Traveler and all Cheetahs and Tigers must be trimmed to clear the different contour of the starter motor and solenoid.

Here are some examples of the trimming:

[[Image:Center-trim.jpg]]

[[Image:LH-Skytec.jpg]]

This is a seal I added to decrease the air leakage around the starter.

[[Image:Skytec-seal.jpg]]

Also check all of the baffle attach points. This AA5B broken bracket was hard to see, but was obviously not doing it's job. It is attached to the baffles by the oil cooler and held by the upper left engine mount bolt. A previous repair was less than effective. New brackets are available at Fletchair.

[[Image:Broken-baffle-bracket.JPG]]

==Cheetah Baffles - Part of my Hunt for High Oil Temperatures==
I have a Cheetah that suffered from higher oil temperatures than I'm comfortable with (CHT's look OK) during the warmest summer months. Everything has been done to this engine to make it run warm (High Compression mod, LASAR system) so this is not a big surprise. But hearing that people fly these machines in Arizona in the summer and the fact that I'm a bit of a perfectionist...I wanted to see if there is anything I could do to lower the temps.

In the course of chasing down the issue, (besides checking the oil cooler, vernatherm valve, and other system components) the old and ratty baffle seals were replaced under the supervision of one of the most Grumman knowledgeable shops around. After the seals were replaced, the following summer my temperatures were actually worse than the previous year. And thus began my education in the proper fit of baffle seals...

===Finding Problems===
I started by simply taking a flashlight and looking into the cooling air intakes in the nose bowl. I found several places where the seals did not sit flush against the cowl. In one location the seal bowed enough to create a quarter sized hole. This occurred because in the replacement of the seals, the multiple separate pieces of seal material were replaced with a few single longer strips of seal material. Where the seals along the back and sides overlapped, they were attached together in such a way as to pull them away from the cowl. So, I removed these attachments and determined where to cut slits in the seal material so it would sit flush.

I then started looking around the nose bowl seals and found a number of locations where the seal fit was as poor as the seals against the cowl doors. I had to pull the cowl and hold the nose bowl in position as best I could (by holding it relative to the spinner/prop just as it looked when the cowl was attached) and inspect the seal fit. I used a marker to mark the locations where the seal did not fit well and made a number of additional slits in the ribbons of seal material. Often these slits were made where the contours of the cowl or nose bowl change. There was also a location near the alternator where a longer strip of seal material was needed to close a hole caused by the additional distance between the baffle and the nose bowl in that area.

After 20 or more new slits in the baffle seal material and a new piece near the alternator, I put things back together and used a combination of drop lights and flashlights to check how well the seals were seating. Everything looked good, so I reassembled the cowl, checked the baffles one more time, and waited for the warm summer days to return for the tests.

===Test Flight===
Well, summer returned and I went on a test flight. The temps were lower...but only back to the point they were prior to replacing the seals. So, I continued my search. Off came the cowl and nose bowl and I found the seal around the starter (a location Bob mentioned above) was not that tight in spots and completely missing along the top of the starter (between the starter and the engine case) in what would equate to about a 1" x 3" hole. So, I constructed and installed a seal to close the hole. I also replaced the seal around the pipe that provides air to the muffler shroud as I determined the seal material there was the original and in bad shape. I then put everything back together and and performed a couple test flights. Things were looking better, but when the high temps of July and August hit, the oil temps wee still a bit high.

===Gathering Data===
Stumped, I decided to try collecting some figures on the cooling. I constructed a simple water manometer to determine the pressure differential between the high pressure and low pressure side of the baffles. After some searching around the internet, I found that for effective cooling you need a pressure difference of at least 6" of water. We ran the tubing ends of the manometer from the cockpit out the canopy and in thru the oil door with one tube on each side of the baffle in the cowl. In flight we were able to determine that in cruise around 120 mph IAS the pressure difference was right around 6" of water. In a 100 mph IAS climb, the pressure dropped to around 5". So, the numbers indicated that I still had some issues as I was just barely coming into an acceptable cooling pressure range in cruise.

===The latest (and hopefully last) find===
So, my A&P (who had been overseeing my work all along) and I tried to find any other possible problems. After a bunch of snooping around with flashlights and inspection mirrors, my A&P was able to find another hole hiding in the seals. This hole was located just above the airbox and was caused by the fact that the standard width of the seal material sold in rolls is not wide enough to close a gap in that area. So, I obtained a larger piece of seal material (around 4.5" wide, if memory serves), off came the cowl and nose bowl again, and replaced the pieces that were too short.

===Pictures of the Results===
Below are several pictures of my baffle seals after the changes. Sorry, I didn't take any before pictures, maybe I'll remember next time.
''coming soon''

===Conclusion (sort of)===
Of course, by the time we found and fixed this issue, the hot summer temperatures had given way to cooler ones of fall. The oil temperatures have looked good since the last fix, but I guess I won't know for sure if the problem is resolved until summer returns again. I'll probably try the manometer again to see what it says...when my mechanic and I get a chance. I'll keep you posted. In the meantime, I hope this information helps if you have a Cheetah experiencing similar issues.

One last note. I was supplied the silicone type baffle seal material by the shop where the seals were initially replaced. I've found that this material isn't necessarily the best for seals as it is rather thick and does not "set" (retain a curved form) so you have to wrestle with it and be careful of the fit anytime you need to close the cowl or install the nose bowl.

User:Mboyd

2008-03-21T00:36:17Z

Mboyd:

Hi,
I'm Mike Boyd and this is my 1976 Grumman Cheetah N9811U.

[[Image:N9811U.jpg|400 px|1976 Cheetah N9811U]]

We are based in Erie Colorado ([http://www.airnav.com/airport/KEIK KEIK]). I purchased N9811U in March 2005 and it is the first Grumman I've owned or flown.

The picture above was taken in Snyder Texas ([http://www.airnav.com/airport/KSNK KSNK])during my first "real" cross country trip where my wife and I and our two dogs went to [http://www.sopadre.com S. Padre Island Texas].

Oil Change with Remote Filter and Quick Drain

2008-02-10T16:10:56Z

Mboyd:

After a few questions posted to the Grumman Gang I thought I would document my procedure for changing the oil in my '76 Cheetah. I keep refining it as I go, but I hope this provides some useful tips for those who wish to do your own oil changes.

First, as Norm would say, a note about shop safety: Always wear safely glasses and other appropriate protection. I believe this, like most owner maintenance, must be done with the supervision of an A&P the first time.

Here's how it went for me at my last oil change...took less than an hour from hangar door up to hangar door down (not including the short flight to warm up the oil). My Cheetah is equipped with an oil quick drain valve and an Airwolf remote mounted oil filter...I recommend both if you plan to regularly change your oil.

'''The Supplies'''
<ul>
<li>One 5 gallon Kikkoman soy sauce bucket, empty, with tabs on lid cut so the lid can be removed (scavenged from a local Chinese restaurant).
<li>2~3ft of surgical tubing (diameter to fit the oil quick drain valve).
<li>8 qts appropriate oil
<li>Oil filter to fit remote mounted oil filter adapter.
<li>Wrench to remove oil filter (I use a socket wrench w/ pivoting head & socket).
<li>Safety wire & safety wire pliers (the cheap ones at Harbor Freight work just fine...and are worth it)
<li>Newspaper (oil filter is mounted upside down, still haven't figured out a good way to get it out without some oil spillage).
</ul>

'''Why a Kikkoman soy sauce bucket''' 
Now I know you are asking why I specified this bucket...well...actually any bucket that has a lid that seals and contains one of those extendable pour spouts will do.
The advantages to the Kikkoman (or similar) bucket:
<ul>
<li>Free from your favorite local Chinese restaurant.
<li>Convenient carrying handle.
<li>Can hold between 2~3 oil changes worth of oil depending on quantity at oil change time.
<li>Lid seals tight so spout can be used to pour oil out.
<li>Bucket with lid on and pour spout extended fits under cowl of the Cheetah
<li>Bucket fits well on most local oil collection tanks. Just open/extend the pour spout and set upside down over oil collection tank opening until bucket drains.
<li>Makes people wonder why you are taking a 5 gallon bucket of Kikkoman Soy Sauce into/out of the local Auto Zone, Napa, etc store. ;-)
</ul>

'''The Hose''' 
I've used a length of clear surgical tubing and have had no problems, but others have mentioned that the hose can slip off the quick drain. So, others have recommended using heater hose or using safety wire or some sort of clamp to hold the tube in place. Feel free to experiment as that will be far more fun than cleaning up 8 quarts of oil from inside your cowl and the surrounding floor. I'd also recommend not applying any forces to the hose while the oil drains.
Another tip I've received is that, if you use the surgical tubing or other soft walled tube, don't fold it but coil it up for storage. Otherwise the hose may remain kinked when unfolded.

'''The Process'''<OL>
<li>Run engine to heat oil so it flows easier...a great excuse to go flying.

<li>Open cowl so you can access filter and quick drain.

<li>Extend spout and remove cap on bucket, insert one end of hose into spout on bucket. 
[[Image:oil_bucket.JPG]]

<li>Snake other end of hose thru lower cowl opening and slide over quick drain. 
[[Image:oil_quick_drain.JPG]]

<li>Open quick drain. Remove oil dipstick. Let the oil drain.

<li>Place a number of sheets of newspaper under the oil filter, shape so it will collect any oil. Consider how you plan on moving the oil filter when laying out the paper. Since the filter is mounted upside down (like a cup), there will be oil that will spill out when removed. 
I know some gang members have devised containers to catch oil from the filter area such as cutting apart an oil quart container or gallon milk jug...they don't fit well in my setup, but it may work for you.

<li>Remove safety wire and old filter. Set filter down so it doesn't spill oil (can use box it came in).

<li>Wipe mounting surface clean, inspect for any damage. Remove newspaper.

<li>Install new oil filter per instructions (gasket lube, tightening recommendations). Safety wire so it can not unscrew.

<li>Close quick drain and remove hose. Allow hose to drain into bucket. Use small amount of paper towel to seal ends of tube when done.

<li>Wipe off any drips from the quick drain (and cowling, but there shouldn't be any there). Confirm quick drain is closed.

<li>Put cap on spout of bucket, remove bucket lid and place upside down on floor.

<li>Pour any remaining oil from filter into bucket, then place filter with hole down on the upside down lid to finish draining (the last tablespoon or two of oil).

<li>Add 8 qts oil to engine. ''Tip:'' oil container quarts can actually screw into the oil filler neck - Don't force it, just give it a 1/2 twist or so and let it sit until empty (something I learned from my A&P the first time). 
[[Image:filter_quart.JPG]]

<li>Replace dipstick, remove all tools from engine area, and button everything back up.

<li>Start engine, verify oil pressure comes alive quickly, Run engine for several minutes, shut down.

<li>Open cowl, inspect for any leaks. Check quick drain, oil filter/screen area, etc. Close cowl.

<li>Get oil filter draining on bucket lid, wipe it off, and cut open for inspection (or put in box and take to your A&P and ask them to cut it open...most around here will do it free of charge if you are a customer...it's what I actually do). Verify no metal in filter element.

<li>Put lid (with small amount of oil from the final draining of the filter), back on the bucket. Make sure lid seals.

<li>Note tach time. Add entry to engine log (the job ain't done until the paperwork is). ;-)

<li>You're done.
</OL>

...well...Ok, every 2 or 3 oil changes, go empty the bucket. I believe it is U.S. law that requires anyone that sells engine oil to collect used engine oil for recycling. I've also heard that some folks use heaters in their hangars that can burn used oil. I'm sure you'll find some legal and environmentally friendly means to dispose of the oil.

I hope you found this interesting. Please feel free to add to this if you have other tips and tricks...I'm always looking for a way to make it easier...even though this process is far easier than changing the oil on any of my cars.

Happy Flying. 
-Mike

Oil Change with Remote Filter and Quick Drain

2008-02-10T16:08:26Z

Mboyd:

After a few questions posted to the Grumman Gang I thought I would document my procedure for changing the oil in my '76 Cheetah. I keep refining it as I go, but I hope this provides some useful tips for those who wish to do your own oil changes.

First, as Norm would say, a note about shop safety: Always wear safely glasses and other appropriate protection. I believe this, like most owner maintenance, must be done with the supervision of an A&P the first time.

Here's how it went for me at my last oil change...took less than an hour from hangar door up to hangar door down (not including the short flight to warm up the oil). My Cheetah is equipped with an oil quick drain valve and an Airwolf remote mounted oil filter...I recommend both if you plan to regularly change your oil.

'''The Supplies'''
<ul>
<li>One 5 gallon Kikkoman soy sauce bucket, empty, with tabs on lid cut so the lid can be removed (scavenged from a local Chinese restaurant).
<li>2~3ft of surgical tubing (diameter to fit the oil quick drain valve).
<li>8 qts appropriate oil
<li>Oil filter to fit remote mounted oil filter adapter.
<li>Wrench to remove oil filter (I use an adjustable).
<li>Safety wire & safety wire pliers (the cheap ones at Harbor Freight work just fine...and are worth it)
<li>Newspaper (oil filter is mounted upside down, still haven't figured out a good way to get it out without some oil spillage).
</ul>

'''Why a Kikkoman soy sauce bucket''' 
Now I know you are asking why I specified this bucket...well...actually any bucket that has a lid that seals and contains one of those extendable pour spouts will do.
The advantages to the Kikkoman (or similar) bucket:
<ul>
<li>Free from your favorite local Chinese restaurant.
<li>Convenient carrying handle.
<li>Can hold between 2~3 oil changes worth of oil depending on quantity at oil change time.
<li>Lid seals tight so spout can be used to pour oil out.
<li>Bucket with lid on and pour spout extended fits under cowl of the Cheetah
<li>Bucket fits well on most local oil collection tanks. Just open/extend the pour spout and set upside down over oil collection tank opening until bucket drains.
<li>Makes people wonder why you are taking a 5 gallon bucket of Kikkoman Soy Sauce into/out of the local Auto Zone, Napa, etc store. ;-)
</ul>

'''The Hose''' 
I've used a length of clear surgical tubing and have had no problems, but others have mentioned that the hose can slip off the quick drain. So, others have recommended using heater hose or using safety wire or some sort of clamp to hold the tube in place. Feel free to experiment as that will be far more fun than cleaning up 8 quarts of oil from inside your cowl and the surrounding floor. I'd also recommend not applying any forces to the hose while the oil drains.
Another tip I've received is that, if you use the surgical tubing or other soft walled tube, don't fold it but coil it up for storage. Otherwise the hose may remain kinked when unfolded.

'''The Process'''<OL>
<li>Run engine to heat oil so it flows easier...a great excuse to go flying.

<li>Open cowl so you can access filter and quick drain.

<li>Extend spout and remove cap on bucket, insert one end of hose into spout on bucket. 
[[Image:oil_bucket.JPG]]

<li>Snake other end of hose thru lower cowl opening and slide over quick drain. 
[[Image:oil_quick_drain.JPG]]

<li>Open quick drain. Remove oil dipstick. Let the oil drain.

<li>Place a number of sheets of newspaper under the oil filter, shape so it will collect any oil. Consider how you plan on moving the oil filter when laying out the paper. Since the filter is mounted upside down (like a cup), there will be oil that will spill out when removed. 
I know some gang members have devised containers to catch oil from the filter area such as cutting apart an oil quart container or gallon milk jug...they don't fit well in my setup, but it may work for you.

<li>Remove safety wire and old filter. Set filter down so it doesn't spill oil (can use box it came in).

<li>Wipe mounting surface clean, inspect for any damage. Remove newspaper.

<li>Install new oil filter per instructions (gasket lube, tightening recommendations). Safety wire so it can not unscrew.

<li>Close quick drain and remove hose. Allow hose to drain into bucket. Use small amount of paper towel to seal ends of tube when done.

<li>Wipe off any drips from the quick drain (and cowling, but there shouldn't be any there). Confirm quick drain is closed.

<li>Put cap on spout of bucket, remove bucket lid and place upside down on floor.

<li>Pour any remaining oil from filter into bucket, then place filter with hole down on the upside down lid to finish draining (the last tablespoon or two of oil).

<li>Add 8 qts oil to engine. ''Tip:'' oil container quarts can actually screw into the oil filler neck - Don't force it, just give it a 1/2 twist or so and let it sit until empty (something I learned from my A&P the first time). 
[[Image:filter_quart.JPG]]

<li>Replace dipstick, remove all tools from engine area, and button everything back up.

<li>Start engine, verify oil pressure comes alive quickly, Run engine for several minutes, shut down.

<li>Open cowl, inspect for any leaks. Check quick drain, oil filter/screen area, etc. Close cowl.

<li>Get oil filter draining on bucket lid, wipe it off, and cut open for inspection (or put in box and take to your A&P and ask them to cut it open...most around here will do it free of charge if you are a customer...it's what I actually do). Verify no metal in filter element.

<li>Put lid (with small amount of oil from the final draining of the filter), back on the bucket. Make sure lid seals.

<li>Note tach time. Add entry to engine log (the job ain't done until the paperwork is). ;-)

<li>You're done.
</OL>

...well...Ok, every 2 or 3 oil changes, go empty the bucket. I believe it is U.S. law that requires anyone that sells engine oil to collect used engine oil for recycling. I've also heard that some folks use heaters in their hangars that can burn used oil. I'm sure you'll find some legal and environmentally friendly means to dispose of the oil.

I hope you found this interesting. Please feel free to add to this if you have other tips and tricks...I'm always looking for a way to make it easier...even though this process is far easier than changing the oil on any of my cars.

Happy Flying. 
-Mike

File:Oil bucket.JPG

2008-02-10T16:00:14Z

Mboyd: Oil drain setup with bucket

Oil drain setup with bucket

File:Filter quart.JPG

2008-02-10T15:59:05Z

Mboyd: Airwolf remote oil filter mount and trick to add a quart of oil.

Airwolf remote oil filter mount and trick to add a quart of oil.

File:Oil quick drain.JPG

2008-02-10T15:58:06Z

Mboyd: Connecting tubing to the oil quick drain.

Connecting tubing to the oil quick drain.

Oil Change with Remote Filter and Quick Drain

2006-06-30T16:40:22Z

Mboyd:

After a few questions posted to the Grumman Gang I thought I would document my procedure for changing the oil in my '76 Cheetah. I keep refining it as I go, but I hope this provides some useful tips for those who wish to do your own oil changes. I hope to take some pictures of the setup/process next time, but for now here is the text description.

First, as Norm would say, a note about shop safety: Always wear safely glasses and other appropriate protection. I believe this, like most owner maintenance, must be done with the supervision of an A&P the first time.

Here's how it went for me at my last oil change...took less than an hour from hangar door up to hangar door down (not including the short flight to warm up the oil). My Cheetah is equipped with an oil quick drain valve and an Airwolf remote mounted oil filter...I recommend both if you plan to regularly change your oil.

'''The Supplies'''
<ul>
<li>One 5 gallon Kikkoman soy sauce bucket, empty, with tabs on lid cut so the lid can be removed (scavenged from a local Chinese restaurant).
<li>2~3ft of surgical tubing (diameter to fit the oil quick drain valve).
<li>8 qts appropriate oil
<li>Oil filter to fit remote mounted oil filter adapter.
<li>Wrench to remove oil filter (I use an adjustable).
<li>Safety wire & safety wire pliers (the cheap ones at Harbor Freight work just fine...and are worth it)
<li>Newspaper (oil filter is mounted upside down, still haven't figured out a good way to get it out without some oil spillage).
</ul>

'''Why a Kikkoman soy sauce bucket''' 
Now I know you are asking why I specified this bucket...well...actually any bucket that has a lid that seals and contains one of those extendable pour spouts will do.
The advantages to the Kikkoman (or similar) bucket:
<ul>
<li>Free from your favorite local Chinese restaurant.
<li>Convenient carrying handle.
<li>Can hold between 2~3 oil changes worth of oil depending on quantity at oil change time.
<li>Lid seals tight so spout can be used to pour oil out.
<li>Bucket with lid on and pour spout extended fits under cowl of the Cheetah
<li>Bucket fits well on most local oil collection tanks. Just open/extend the pour spout and set upside down over oil collection tank opening until bucket drains.
<li>Makes people wonder why you are taking a 5 gallon bucket of Kikkoman Soy Sauce into/out of the local Auto Zone, Napa, etc store. ;-)
</ul>

'''The Hose''' 
I've used a length of clear surgical tubing and have had no problems, but others have mentioned that the hose can slip off the quick drain. So, others have recommended using heater hose or using safety wire or some sort of clamp to hold the tube in place. Feel free to experiment as that will be far more fun than cleaning up 8 quarts of oil from inside your cowl and the surrounding floor. I'd also recommend not applying any forces to the hose while the oil drains.
Another tip I've received is that, if you use the surgical tubing or other soft walled tube, don't fold it but coil it up for storage. Otherwise the hose may remain kinked when unfolded.

'''The Process'''<OL>
<li>Run engine to heat oil so it flows easier...a great excuse to go flying.

<li>Open cowl so you can access filter and quick drain.

<li>Extend spout and remove cap on bucket, insert one end of hose into spout on bucket.

<li>Snake other end of hose thru lower cowl opening and slide over quick drain.

<li>Open quick drain. Remove oil dipstick. Let the oil drain.

<li>Place a number of sheets of newspaper under the oil filter, shape so it will collect any oil. Consider how you plan on moving the oil filter when laying out the paper. Since the filter is mounted upside down (like a cup), there will be oil that will spill out when removed. 
I know some gang members have devised containers to catch oil from the filter area such as cutting apart an oil quart container or gallon milk jug...they don't fit well in my setup, but it may work for you.

<li>Remove safety wire and old filter. Set filter down so it doesn't spill oil (can use box it came in).

<li>Wipe mounting surface clean, inspect for any damage. Remove newspaper.

<li>Install new oil filter per instructions (gasket lube, tightening recommendations). Safety wire so it can not unscrew.

<li>Close quick drain and remove hose. Allow hose to drain into bucket. Use small amount of paper towel to seal ends of tube when done.

<li>Wipe off any drips from the quick drain (and cowling, but there shouldn't be any there). Confirm quick drain is closed.

<li>Put cap on spout of bucket, remove bucket lid and place upside down on floor.

<li>Pour any remaining oil from filter into bucket, then place filter with hole down on the upside down lid to finish draining (the last tablespoon or two of oil).

<li>Add 8 qts oil to engine. ''Tip:'' oil container quarts can actually screw into the oil filler neck - Don't force it, just give it a 1/2 twist or so and let it sit until empty (something I learned from my A&P the first time).

<li>Replace dipstick, remove all tools from engine area, and button everything back up.

<li>Start engine, verify oil pressure comes alive quickly, Run engine for several minutes, shut down.

<li>Open cowl, inspect for any leaks. Check quick drain, oil filter/screen area, etc. Close cowl.

<li>Get oil filter draining on bucket lid, wipe it off, and cut open for inspection (or put in box and take to your A&P and ask them to cut it open...most around here will do it free of charge if you are a customer...it's what I actually do). Verify no metal in filter element.

<li>Put lid (with small amount of oil from the final draining of the filter), back on the bucket. Make sure lid seals.

<li>Note tach time. Add entry to engine log (the job ain't done until the paperwork is). ;-)

<li>You're done.
</OL>

...well...Ok, every 2 or 3 oil changes, go empty the bucket. I believe it is U.S. law that requires anyone that sells engine oil to collect used engine oil for recycling. I've also heard that some folks use heaters in their hangars that can burn used oil. I'm sure you'll find some legal and environmentally friendly means to dispose of the oil.

I hope you found this interesting. Please feel free to add to this if you have other tips and tricks...I'm always looking for a way to make it easier...even though this process is far easier than changing the oil on any of my cars.

Happy Flying. 
-Mike

Oil Change with Remote Filter and Quick Drain

2006-06-30T16:38:45Z

Mboyd:

After a few questions posted to the Grumman Gang I thought I would document my procedure for changing the oil in my '76 Cheetah. I keep refining it as I go, but I hope this provides some useful tips for those who wish to do your own oil changes. I hope to take some pictures of the setup/process next time, but for now here is the text description.

First, as Norm would say, a note about shop safety: Always wear safely glasses and other appropriate protection. I believe this, like most owner maintenance, must be done with the supervision of an A&P the first time.

Here's how it went for me at my last oil change...took less than an hour from hangar door up to hangar door down (not including the short flight to warm up the oil). My Cheetah is equipped with an oil quick drain valve and an Airwolf remote mounted oil filter...I recommend both if you plan to regularly change your oil.

'''The Supplies'''
<ul>
<li>One 5 gallon Kikkoman soy sauce bucket, empty, with tabs on lid cut so the lid can be removed (scavenged from a local Chinese restaurant).
<li>2~3ft of surgical tubing (diameter to fit the oil quick drain valve).
<li>8 qts appropriate oil
<li>Oil filter to fit remote mounted oil filter adapter.
<li>Wrench to remove oil filter (I use an adjustable).
<li>Safety wire & safety wire pliers (the cheap ones at Harbor Freight work just fine...and are worth it)
<li>Newspaper (oil filter is mounted upside down, still haven't figured out a good way to get it out without some oil spillage).
</ul>

'''Why a Kikkoman soy sauce bucket''' 
Now I know you are asking why I specified this bucket...well...actually any bucket that has a lid that seals and contains one of those extendable pour spouts will do.
The advantages to the Kikkoman (or similar) bucket:
<ul>
<li>Free from your favorite local Chinese restaurant.
<li>Convenient carrying handle.
<li>Can hold between 2~3 oil changes worth of oil depending on quantity at oil change time.
<li>Lid seals tight so spout can be used to pour oil out.
<li>Bucket with lid on and pour spout extended fits under cowl of the Cheetah
<li>Bucket fits well on most local oil collection tanks. Just open/extend the pour spout and set upside down over oil collection tank opening until bucket drains.
<li>Makes people wonder why you are taking a 5 gallon bucket of Kikkoman Soy Sauce into/out of the local Auto Zone, Napa, etc store. ;-)
</ul>

'''The Hose''' 
I've used a length of clear surgical tubing and have had no problems, but others have mentioned that the hose can slip off the quick drain. So, others have recommended using heater hose or using safety wire or some sort of clamp to hold the tube in place. Feel free to experiment as that will be far more fun than cleaning up 8 quarts of oil from inside your cowl and the surrounding floor. I'd also recommend not applying any forces to the hose while the oil drains.
Another tip I've received is that, if you use the surgical tubing or other soft walled tube, don't fold it but coil it up for storage. Otherwise the hose may remain kinked when unfolded.

'''The Process'''<OL>
<li>Run engine to heat oil so it flows easier...a great excuse to go flying.

<li>Extend spout and remove cap on bucket, insert one end of hose into spout on bucket.

<li>Snake other end of hose thru lower cowl opening and slide over quick drain.

<li>Open quick drain. Remove oil dipstick. Let the oil drain.

<li>Place a number of sheets of newspaper under the oil filter, shape so it will collect any oil. Consider how you plan on moving the oil filter when laying out the paper. Since the filter is mounted upside down (like a cup), there will be oil that will spill out when removed. 
I know some gang members have devised containers to catch oil from the filter area such as cutting apart an oil quart container or gallon milk jug...they don't fit well in my setup, but it may work for you.

<li>Remove safety wire and old filter. Set filter down so it doesn't spill oil (can use box it came in).

<li>Wipe mounting surface clean, inspect for any damage. Remove newspaper.

<li>Install new oil filter per instructions (gasket lube, tightening recommendations). Safety wire so it can not unscrew.

<li>Close quick drain and remove hose. Allow hose to drain into bucket. Use small amount of paper towel to seal ends of tube when done.

<li>Wipe off any drips from the quick drain (and cowling, but there shouldn't be any there). Confirm quick drain is closed.

<li>Put cap on spout of bucket, remove bucket lid and place upside down on floor.

<li>Pour any remaining oil from filter into bucket, then place filter with hole down on the upside down lid to finish draining (the last tablespoon or two of oil).

<li>Add 8 qts oil to engine. ''Tip:'' oil container quarts can actually screw into the oil filler neck - Don't force it, just give it a 1/2 twist or so and let it sit until empty (something I learned from my A&P the first time).

<li>Replace dipstick, remove all tools from engine area, and button everything back up.

<li>Start engine, verify oil pressure comes alive quickly, Run engine for several minutes, shut down.

<li>Open cowl, inspect for any leaks. Check quick drain, oil filter/screen area, etc. Close cowl.

<li>Get oil filter draining on bucket lid, wipe it off, and cut open for inspection (or put in box and take to your A&P and ask them to cut it open...most around here will do it free of charge if you are a customer...it's what I actually do). Verify no metal in filter element.

<li>Put lid (with small amount of oil from the final draining of the filter), back on the bucket. Make sure lid seals.

<li>Note tach time. Add entry to engine log (the job ain't done until the paperwork is). ;-)

<li>You're done.
</OL>

...well...Ok, every 2 or 3 oil changes, go empty the bucket. I believe it is U.S. law that requires anyone that sells engine oil to collect used engine oil for recycling. I've also heard that some folks use heaters in their hangars that can burn used oil. I'm sure you'll find some legal and environmentally friendly means to dispose of the oil.

I hope you found this interesting. Please feel free to add to this if you have other tips and tricks...I'm always looking for a way to make it easier...even though this process is far easier than changing the oil on any of my cars.

Happy Flying. 
-Mike

Oil Change with Remote Filter and Quick Drain

2006-06-30T16:33:49Z

Mboyd: /* Changing the Oil and Filter in my '76 Cheetah */

After a few questions posted to the Grumman Gang I thought I would document my procedure for changing the oil in my '76 Cheetah. I keep refining it as I go, but I hope this provides some useful tips for those who wish to do your own oil changes. I hope to take some pictures of the setup/process next time, but for now here is the text description.

First, as Norm would say, a note about shop safety: Always wear safely glasses and other appropriate protection. I believe this, like most owner maintenance, must be done with the supervision of an A&P the first time.

Here's how it went for me at my last oil change...took less than an hour from hangar door up to hangar door down (not including the short flight to warm up the oil). My Cheetah is equipped with an oil quick drain valve and an Airwolf remote mounted oil filter...I recommend both if you plan to regularly change your oil.

'''The Supplies'''
<ul>
<li>One 5 gallon Kikkoman soy sauce bucket, empty, with tabs on lid cut so the lid can be removed (scavenged from a local Chinese restaurant).
<li>2~3ft of surgical tubing (diameter to fit the oil quick drain valve).
<li>8 qts appropriate oil
<li>Oil filter to fit remote mounted oil filter adapter.
<li>Wrench to remove oil filter (I use an adjustable).
<li>Safety wire & safety wire pliers (the cheap ones at Harbor Freight work just fine...and are worth it)
<li>Newspaper (oil filter is mounted upside down, still haven't figured out a good way to get it out without some oil spillage).
</ul>

'''Why a Kikkoman soy sauce bucket''' 
Now I know you are asking why I specified this bucket...well...actually any bucket that has a lid that seals and contains one of those extendable pour spouts will do.
The advantages to the Kikkoman (or similar) bucket:
<ul>
<li>Free from your favorite local Chinese restaurant.
<li>Convenient carrying handle.
<li>Can hold between 2~3 oil changes worth of oil depending on quantity at oil change time.
<li>Lid seals tight so spout can be used to pour oil out.
<li>Bucket fits well on most local oil collection tanks. Just open/extend the pour spout and set upside down over oil collection tank opening until bucket drains.
<li>Makes people wonder why you are taking a 5 gallon bucket of Kikkoman Soy Sauce into/out of the local Auto Zone, Napa, etc store. ;-)
</ul>

'''The Hose''' 
I've used a length of clear surgical tubing and have had no problems, but others have mentioned that the hose can slip off the quick drain. So, others have recommended using heater hose or using safety wire or some sort of clamp to hold the tube in place. Feel free to experiment as that will be far more fun than cleaning up 8 quarts of oil from inside your cowl and the surrounding floor. I'd also recommend not applying any forces to the hose while the oil drains.
Another tip I've received is that, if you use the surgical tubing or other soft walled tube, don't fold it but coil it up for storage. Otherwise the hose may remain kinked when unfolded.

'''The Process'''<OL>
<li>Run engine to heat oil so it flows easier...a great excuse to go flying.

<li>Extend spout and remove cap on bucket, insert one end of hose into spout on bucket.

<li>Snake other end of hose thru lower cowl opening and slide over quick drain.

<li>Open quick drain. Remove oil dipstick. Let the oil drain.

<li>Place a number of sheets of newspaper under the oil filter, shape so it will collect any oil. Consider how you plan on moving the oil filter when laying out the paper. Since the filter is mounted upside down (like a cup), there will be oil that will spill out when removed. 
I know some gang members have devised containers to catch oil from the filter area such as cutting apart an oil quart container or gallon milk jug...they don't fit well in my setup, but it may work for you.

<li>Remove safety wire and old filter. Set filter down so it doesn't spill oil (can use box it came in).

<li>Wipe mounting surface clean, inspect for any damage. Remove newspaper.

<li>Install new oil filter per instructions (gasket lube, tightening recommendations). Safety wire so it can not unscrew.

<li>Close quick drain and remove hose. Allow hose to drain into bucket. Use small amount of paper towel to seal ends of tube when done.

<li>Wipe off any drips from the quick drain (and cowling, but there shouldn't be any there). Confirm quick drain is closed.

<li>Put cap on spout of bucket, remove bucket lid and place upside down on floor.

<li>Pour any remaining oil from filter into bucket, then place filter with hole down on the upside down lid to finish draining (the last tablespoon or two of oil).

<li>Add 8 qts oil to engine. ''Tip:'' oil container quarts can actually screw into the oil filler neck - Don't force it, just give it a 1/2 twist or so and let it sit until empty (something I learned from my A&P the first time).

<li>Replace dipstick, remove all tools from engine area, and button everything back up.

<li>Start engine, verify oil pressure comes alive quickly, Run engine for several minutes, shut down.

<li>Open cowl, inspect for any leaks. Check quick drain, oil filter/screen area, etc. Close cowl.

<li>Get oil filter draining on bucket lid, wipe it off, and cut open for inspection (or put in box and take to your A&P and ask them to cut it open...most around here will do it free of charge if you are a customer...it's what I actually do). Verify no metal in filter element.

<li>Put lid (with small amount of oil from the final draining of the filter), back on the bucket. Make sure lid seals.

<li>Note tach time. Add entry to engine log (the job ain't done until the paperwork is). ;-)

<li>You're done.
</OL>

...well...Ok, every 2 or 3 oil changes, go empty the bucket. I believe it is U.S. law that requires anyone that sells engine oil to collect used engine oil for recycling. I've also heard that some folks use heaters in their hangars that can burn used oil. I'm sure you'll find some legal and environmentally friendly means to dispose of the oil.

I hope you found this interesting. Please feel free to add to this if you have other tips and tricks...I'm always looking for a way to make it easier...even though this process is far easier than changing the oil on any of my cars.

Happy Flying. 
-Mike

Oil Change with Remote Filter and Quick Drain

2006-06-30T16:32:19Z

Mboyd:

== Changing the Oil and Filter in my '76 Cheetah ==

After a few questions posted to the Grumman Gang I thought I would document my procedure for changing the oil in my plane. I keep refining it as I go, but I hope this provides some useful tips for those who wish to do your own oil changes. I hope to take some pictures of the setup/process next time, but for now here is the text description.

First, as Norm would say, a note about shop safety: Always wear safely glasses and other appropriate protection. I believe this, like most owner maintenance, must be done with the supervision of an A&P the first time.

Here's how it went for me at my last oil change...took less than an hour from hangar door up to hangar door down (not including the short flight to warm up the oil). My Cheetah is equipped with an oil quick drain valve and an Airwolf remote mounted oil filter...I recommend both if you plan to regularly change your oil.

'''The Supplies'''
<ul>
<li>One 5 gallon Kikkoman soy sauce bucket, empty, with tabs on lid cut so the lid can be removed (scavenged from a local Chinese restaurant).
<li>2~3ft of surgical tubing (diameter to fit the oil quick drain valve).
<li>8 qts appropriate oil
<li>Oil filter to fit remote mounted oil filter adapter.
<li>Wrench to remove oil filter (I use an adjustable).
<li>Safety wire & safety wire pliers (the cheap ones at Harbor Freight work just fine...and are worth it)
<li>Newspaper (oil filter is mounted upside down, still haven't figured out a good way to get it out without some oil spillage).
</ul>

'''Why a Kikkoman soy sauce bucket''' 
Now I know you are asking why I specified this bucket...well...actually any bucket that has a lid that seals and contains one of those extendable pour spouts will do.
The advantages to the Kikkoman (or similar) bucket:
<ul>
<li>Free from your favorite local Chinese restaurant.
<li>Convenient carrying handle.
<li>Can hold between 2~3 oil changes worth of oil depending on quantity at oil change time.
<li>Lid seals tight so spout can be used to pour oil out.
<li>Bucket fits well on most local oil collection tanks. Just open/extend the pour spout and set upside down over oil collection tank opening until bucket drains.
<li>Makes people wonder why you are taking a 5 gallon bucket of Kikkoman Soy Sauce into/out of the local Auto Zone, Napa, etc store. ;-)
</ul>

'''The Hose''' 
I've used a length of clear surgical tubing and have had no problems, but others have mentioned that the hose can slip off the quick drain. So, others have recommended using heater hose or using safety wire or some sort of clamp to hold the tube in place. Feel free to experiment as that will be far more fun than cleaning up 8 quarts of oil from inside your cowl and the surrounding floor. I'd also recommend not applying any forces to the hose while the oil drains.
Another tip I've received is that, if you use the surgical tubing or other soft walled tube, don't fold it but coil it up for storage. Otherwise the hose may remain kinked when unfolded.

'''The Process'''<OL>
<li>Run engine to heat oil so it flows easier...a great excuse to go flying.

<li>Extend spout and remove cap on bucket, insert one end of hose into spout on bucket.

<li>Snake other end of hose thru lower cowl opening and slide over quick drain.

<li>Open quick drain. Remove oil dipstick. Let the oil drain.

<li>Place a number of sheets of newspaper under the oil filter, shape so it will collect any oil. Consider how you plan on moving the oil filter when laying out the paper. Since the filter is mounted upside down (like a cup), there will be oil that will spill out when removed. 
I know some gang members have devised containers to catch oil from the filter area such as cutting apart an oil quart container or gallon milk jug...they don't fit well in my setup, but it may work for you.

<li>Remove safety wire and old filter. Set filter down so it doesn't spill oil (can use box it came in).

<li>Wipe mounting surface clean, inspect for any damage. Remove newspaper.

<li>Install new oil filter per instructions (gasket lube, tightening recommendations). Safety wire so it can not unscrew.

<li>Close quick drain and remove hose. Allow hose to drain into bucket. Use small amount of paper towel to seal ends of tube when done.

<li>Wipe off any drips from the quick drain (and cowling, but there shouldn't be any there). Confirm quick drain is closed.

<li>Put cap on spout of bucket, remove bucket lid and place upside down on floor.

<li>Pour any remaining oil from filter into bucket, then place filter with hole down on the upside down lid to finish draining (the last tablespoon or two of oil).

<li>Add 8 qts oil to engine. ''Tip:'' oil container quarts can actually screw into the oil filler neck - Don't force it, just give it a 1/2 twist or so and let it sit until empty (something I learned from my A&P the first time).

<li>Replace dipstick, remove all tools from engine area, and button everything back up.

<li>Start engine, verify oil pressure comes alive quickly, Run engine for several minutes, shut down.

<li>Open cowl, inspect for any leaks. Check quick drain, oil filter/screen area, etc. Close cowl.

<li>Get oil filter draining on bucket lid, wipe it off, and cut open for inspection (or put in box and take to your A&P and ask them to cut it open...most around here will do it free of charge if you are a customer...it's what I actually do). Verify no metal in filter element.

<li>Put lid (with small amount of oil from the final draining of the filter), back on the bucket. Make sure lid seals.

<li>Note tach time. Add entry to engine log (the job ain't done until the paperwork is). ;-)

<li>You're done.
</OL>

...well...Ok, every 2 or 3 oil changes, go empty the bucket. I believe it is U.S. law that requires anyone that sells engine oil to collect used engine oil for recycling. I've also heard that some folks use heaters in their hangars that can burn used oil. I'm sure you'll find some legal and environmentally friendly means to dispose of the oil.

I hope you found this interesting. Please feel free to add to this if you have other tips and tricks...I'm always looking for a way to make it easier...even though this process is far easier than changing the oil on any of my cars.

Happy Flying. 
-Mike

Oil Change with Remote Filter and Quick Drain

2006-06-30T15:29:21Z

Mboyd:

<Coming Very Soon...as soon as I finish typing it up> ;-)

Oil and Filter

2006-06-30T15:28:47Z

Mboyd:

'''Oil and filter or screen serice'''

Until more content is written, take a look at [http://www.lycoming.textron.com/support/aircraftRegistry/oilFilterProcedure.pdf what Lycoming says] about the proper way to inspect filters and screens at oil change.

'''Change your own oil and filter'''

'''Mechanical Difficulty: ''' [[Image:Wrench.jpg]]

Draining the oil from the sump, especially if there is a quick drain installed is an easy job for the owner/pilot. Removing, cleaning and re-installing the pressure screen is also something the owner/pilot can do, after demonstrating the ability to complete it correctly under supervision.

<Coming soon>

Here is a procedure one '76 Cheetah owner uses: [[Oil Change with Remote Filter and Quick Drain]]

User:Mboyd

2006-03-06T17:22:19Z

Mboyd:

Hi,
I'm Mike Boyd and this is my 1976 Grumman Cheetah N9811U.

[[Image:N9811U.jpg|400 px|1976 Cheetah N9811U]]

We are based in Erie Colorado ([http://www.airnav.com/airport/48V 48V]). I purchased N9811U in March 2005 and it is the first Grumman I've owned or flown. We are currently working on my instrument rating and hope to have it by April 2006.

The picutre above was taken in Snyder Texas ([http://www.airnav.com/airport/KSNK KSNK])during my first "real" cross country trip where my wife and I and our two dogs went to [http://www.sopadre.com S. Padre Island Texas].

User:Mboyd

2006-03-06T14:27:07Z

Mboyd:

Hi,
I'm Mike Boyd and this is my 1976 Grumman Cheetah N9811U.

[[Image:N9811U.jpg|400 px|1976 Cheetah N9811U]]

We are based in Erie Colorado ([http://www.airnav.com/airport/48V 48V]).

The Replies

2006-03-06T14:26:22Z

Mboyd:

'''Part 2: Replies'''

Needless to say, the general consensus was that, while this may not be uncommon, I should attempt to find a shop that better meets my expectations. I received a number of responses with specific mechanic recommendations, and expressing their sympathy. I did not want to reproduce all of them here, but I do appreciate them.

Since the original posting, I have found another shop. Below are excerpts of some of the responses that helped me with that decision. (If you wish for me to remove your response for any reason, please let me know):

Andy:
There are about 6 or 7 true Grumman gurus in the country and if you don't go to one of them you are pretty much going to be in charge of quality control....my solution is to work with the mechanics as much as I can during the inspection, accept whatever comes out so long as the paper work is correct and get a guru to do the inspection every few cycles.

Ed:
...You don't necessarily need a "guru" to do a good job. I'd rather have an honest, hardworking, meticulous A&P/AI that has limited Grumman experience work on my plane...If you have a good idea about the "special" areas to look out for (for example, SAIB on the tail bulkheads/stiffeners, Front gear service, delamination, aileron bearing wear, fuel tank leaks, corrosion on the main wing spar as viewed from the landing gear root area and also from the seat area, torque tube condition, slight lifting of cowling doors in flight, baffle/cooling dynamics, oil cooler mount cracking, throttle linkage integrity, and I am sure there are others I am missing) and tune your mechanic in to them then you're just about covered. After all, these planes are much easier (as in not harder) to figure out and maintain than a Cessna or Piper because they are so much simpler.

Steve:
I think you did all the right things in trying to be there for the annual. I think we all would fly and feel safer if we could be at those once a year events. You should have a copy of the maintenance manual with you at all times at an annual. Insist that the A&P follow it as close as possible and practical. The sqwaks you mentioned should never have happened.

And, of course, there were many people that included comments like the following from Dave:
I believe there is nobody better than [http://www.bondline.org/index.php/User:Bob_Steward Bob Steward] [or Cliff, Barry, Ron, etc.], both in knowledge and performance. I feel like I owe him a couple of kilobucks just for the knowledge gained and pain avoided from reading his posts and personal replies.

(Just so you Guru's out there know that the rest of us that are just learning about these fine airplanes appreciate your, sometimes often repeated, advice and understanding!)

Next: [[What I've Learned]]

What I've Learned

2006-03-06T14:08:12Z

Mboyd:

'''Part 3: What I've Learned'''

Since my original post, what I found out was that this shop lost several of their more experienced A&P's that they had just a few years ago and the one that performed my annual just didn't meet my expectations for attention to detail and did not refer to the maintenance manuals that the shop provides for him as often as I would have hoped (as in the case of the dorsal fin removal). As I recall, one of my responses to a private e-mail sent after my original post included the phrase "You can lead an A&P to the Grumman manual, but you can't make him read it" and to me that seems to sum it up.

I'm now using another mechanic and am much happier with their performance. Although my new shop has more experience with those C model aircraft, they appear to me to be much more detail oriented and capable than the first shop (I interviewed the owner and the head mechanic for about an hour each). They have a service that provides them with the manuals for almost all smaller aircraft and demonstrated the system to me. They have fixed many of the problems caused by the first annual and have not caused any additional ones (definitely a step in the right direction).

Here's what I've learned from this experience:
<li> Do your homework. I can't emphasize this enough. If you are reading this, you are probably well on your way to doing that. Find out what to expect from a pre-buy or annual inspection (get the checklists from the maintenance manual, etc). Interview potential mechanics and get references. Talk to other pilots in your area. If you don't have copies of the maintenance and parts manual, get them.</li>
<li> Find a "good" mechanic. Choose a detail-oriented mechanic. A good mechanic that doesn't have as much experience with Grummans is much better than the inverse. Beware of high turn-over rates of mechanics at a given shop (seeing lots of new faces and no old ones at your favorite shop?). Make sure they have, and use, any appropirate manuals.</li>
<li> Be an active participant in your airplane care. Be there for pre-purchase inspections, annuals, etc. Using that homework you can follow along with the mechanic and ask questions. If your mechanic will allow, "owner-assist" on the work. One of the mistakes I made during the annual was that I was not there the entire time. Until you are intimately comfortable with the mechanics work, be there.</li>
<li> If it doesn't "feel right" it probably isn't. Be it the mechanic, a problem with the plane, an explanation, etc. My "normal brake noise" after installation of new brakes & rotors ended up being a mis-installed wheel fairing. Go with your gut instincts.</li>
<li> Know where to go to get answers. The Grumman gang mailing list is an excellent resource and monitored by some very savvy A&P's. The folks at FletchAir, and this site are all good references.</li>
<li> Learn from your experiences. I know it's kinda obvious, but it needs to be said. Adding a fuel line pressurization check to my pre-flight checklist, for example.</li>

Well, I hope that this story has been helpful. Take care and safe and happy flying!

--Mike

What I've Learned

2006-03-06T13:54:39Z

Mboyd:

'''Part 3: What I've Learned'''

Since my original post, what I found out was that this shop lost all the A&P's that they had just a couple years ago (same owners though) and the one they have now just didn't meet my expectations for attention to detail and did not refer to the maintenance manuals that the shop provides for him as often as I would have hoped (as in the case of the dorsal fin removal). As I recall, one of my responses to a private e-mail sent after my original post included the phrase "You can lead an A&P to the Grumman manual, but you can't make him read it" and to me that seems to sum it up.

I'm now using another mechanic am much happier with their performance. Although they have more experience with those C model aircraft, they appear to me to be much more detail oriented and capable than the first shop (I interviewed the owner and the head mechanic for about an hour each). They have fixed many of the problems caused by the first annual and have not caused any additional ones (definitely a step in the right direction).

Here's what I've learned from this experience:
<li> Do your homework. I can't emphasize this enough. If you are reading this, you are probably well on your way to doing that. Find out what to expect from a pre-buy or annual inspection (get the checklists from the maintenance manual, etc). Interview potential mechanics and get references. Talk to other pilots in your area.</li>
<li> Find a "good" mechanic. Choose a detail-oriented mechanic. A good mechanic that doesn't have as much experience with Grummans is much better than the inverse. Beware of high turn-over rates of mechanics at a given shop (seeing lots of new faces and no old ones at your favorite shop?)</li>
<li> Be an active participant in your airplane care. Be there for pre-purchase inspections, annuals, etc. Using that homework you can follow along with the mechanic and ask questions. If your mechanic will allow, "owner-assist" on the work. One of the mistakes I made during the annual was that I was not there the entire time. Until you are intimately comfortable with the mechanics work, be there.</li>
<li> If it doesn't "feel right" it probably isn't. Be it the mechanic, a problem with the plane, an explanation, etc. My "normal brake noise" after installation of new brakes & rotors ended up being a mis-installed wheel fairing. Go with your gut instincts.</li>
<li> Know where to go to get answers. The Grumman gang mailing list is an excellent resource and monitored by some very savvy A&P's. The folks at FletchAir, and this site are all good references.</li>
<li> Learn from your experiences. I know it's kinda obvious, but it needs to be said. Adding a fuel line pressurization check to my pre-flight checklist, for example.</li>

Well, I hope that this story has been helpful. Take care and safe and happy flying!

--Mike

The Annual Inspection

2006-03-06T13:48:38Z

Mboyd:

'''Part 1: The Annual inspection'''

My Cheetah is the first airplane I've owned and we just went thru our first annual together. I thought I'd share my experience and I'm also looking for some "sage advice" on what I should expect in an airplanes condition after it has completed an annual. I have found a number of problems since the airplane was returned to service by the shop (which came recommended by a number of individuals as one that knows Grummans...more on that below).

In addition to the basic annual, my squawk list included a throttle cable that was starting to get stiff, a check of the charging system since a battery recently died (it was unknown age and was a really tired battery), replacement of the aileron bearings/bushings as part of the 100 hour AD (recommended from previous AD compliance), and upgrading to the Boom Beam HID landing light (a x-mas gift from my wife - ain't she great). I had also told them I wanted the wobble check done since it had been over 500 hours since the top overhaul. I had taken off 3 days from work in order to "owner assist" (mostly just help with the access panels and watch and learn).

On the first day of the annual, my skills with a Philips head screwdriver served me well as I removed most of the access panels, the wing tips and, with help, the cowl while the A&P spent a fair amount of the time looking at the HID light STC instructions and doing other prep work. We then went to work on the landing gear, finding that new brakes and discs were needed, cleaning and repacking the bearings. I'm thinking at this point that every airplane owner should definitely do this.

Day two was where it got interesting. Brake parts were on back order and most progress seemed to grind to a halt. The A&P decided that the tasks for the day were to install the HID landing light harness/control and replace the wind-sheared ELT antenna. Since the ELT antenna sits partially inside the vertical fin, the A&P decided he'd have to drill out the pop rivets that hold it to the bottom mounting. Since there are screws at the back of the fin and drilling out all those rivets sounded excessive, I asked if he would call Fletchair and see if there was a trick to this. He declined. Of course, after drilling out the rivets and lifting the fin off of the mount he found the clips that would have allowed removal by just removing the screws and sliding forward a few inches (yes *I* later looked this up in *their* copy of the maintenance manual - 53-0 p202). This, along with a prior incident explaining to them how the aileron AD was supposed to be done (Thanks Bob Steward & Barry), and I start to wonder about the "Grumman experience" of this shop.

Since parts were on back order, I went back to my job for a couple days and did not show back up at the shop until the day the parts were supposed to arrive. When I got there, I found that they had "done the rest" of the inspection and replaced most of the access covers and the lower cowl. So much for learning the rest of that process. All that was left was to finish the brake work and install the throttle cable. I was told that they had another plane coming in and needed to get mine wrapped up. So, the A&P finished the work (brakes and throttle cable) and I reinstalled the wheel fairings. I asked about the results of the wobble check and they said they didn't have the fixture but would order one if I wanted to reschedule another appointment. Hmm...I've only had this scheduled with them for over a month and I specifically asked about this check...oh well.

In hindsight I wish I had been there the entire time my plane was at the shop. After the A&P approved the plane for return to service, I found the following squawks that did not exist prior to the annual:

<li>The elevator would stick at about "neutral" - the problem was a interference by a mis-positioned throttle cable clamp.</li>
<li>The elevator would make a noise when full left aileron was applied - A scat tube had moved into the control path.</li>
<li>The flap fuse was blown and replacement caused immediate fuse failure - A&P said he checked the flaps and they were fine, but the limit switches may now be out of adjustment and the mechanism was jammed in
the up position.</li>
<li>The right brake intermittently loses effectiveness - Cured by bleeding the brakes.</li>
<li>The wheels or brakes make rubbing noises as if a brake is sticking a little and the disc is warped. - This turned out to be a bent wheel fairing bracket. Fixed by my *new* shop.</li>
<li>Fuel was leaking out of the carburetor return hose fitting @ ~4gph(1) They rechecked and tightened the fitting.</li>
<li>My Nav2 radio no longer worked – New mechanic found that the plug had been knocked loose. Now fixed.</li>
<li>Trim around the rear seat belt mounts had been broken (yeah, I know a nit pick and brittle plastic - guess I'll try that MEK and dissolved plastic trick I've been reading about. Of course the guys that replaced all the side window plastic a year earlier managed to do it without breaking the plastic)</li>
<li>The updated W&B, required by the STC, was not placed in the plane (only copy was in their file).</li>

(1)This, unfortunately, was discovered in-flight by my fuel totalizer which was showing an unusual 13GPH consumption rate for my HC Cheetah. Looking inside with the electric pump on, there was an obvious stream (fountain?) of 100LL coming from the fitting. I have since modified my pre-flight checklist to include pressurizing the fuel system before the external walkaround and to check for fuel leak/smell around the cowl.

Now, I understand that my Cheetah's 30th birthday is this year and I would expect that things could potentially fail just after an annual. And I know that problems are why we regularly practice emergency procedures. But to have such a large number, and specifically items that they should have inspected or they touched during the course of their work, be problems immediately after the annual seems to be to be outside the range of normal coincidence. I have since received a copy of the checklist they use for annual inspections and have tried to compare it to the one in the maintenance manual. The one they use is a general checklist and so it includes items not on our planes (such as retractable landing gear checks) but does not include items specific to our cats (like skin bonding issues, canopy issues, etc.). And items on their checklist, like "Flight controls free and correct", do not appear to have been performed after all work was completed. I've founds checks in the inspection checklist in the Grumman Maintenance Manual that should have found all the above problems if done in an appropriate sequence.

So I'm now a little concerned that this annual was not done to the level of detail that I would expect from an inspection designed to verify the operational safety of an aircraft. To their credit, they have been good at working with me to fix the issues.

But like I said, I'm kind of new to this process so I'd like to hear from some of you veteran owners and mechanics out there. On a scale of "Oh, stop your whining" to "Go quickly and find another shop," where do you think this experience belongs?

Next: [[The Replies]]

AA5A

2006-03-04T20:59:46Z

Mboyd:

The AA5A was manufactured from 1976 to 1979 by … in …, (and by …?). It was marketed as the Cheetah.

{|border="1"
|+AA5A Serial Numbers
!Year
!First
!Last
|-
|1976||AA5A-0001||AA5A-xxxx
|-
|1977||AA5A-0001||AA5A-xxxx
|-
|1978||AA5A-0001||AA5A-xxxx
|-
|1979||AA5A-0001||AA5A-xxxx
|}

:

{|border="1"
|+Bondline Contributors Who Own or Fly AA5As
!Name
!Year
!SN
!N Number
!Handle
|-
|[[user:mboyd|Mike Boyd]]||1976||AA5A-0211||N9811U||none
|}

User:Mboyd

2006-03-04T20:49:23Z

Mboyd:

Hi,
I'm Mike and this is my 1976 Grumman Cheetah N9811U.

[[Image:N9811U.jpg|400 px|1976 Cheetah N9811U]]

We are based in Erie Colorado ([http://www.airnav.com/airport/48V 48V]).

User:Mboyd

2006-03-04T20:24:56Z

Mboyd:

Hi,
I'm Mike and this is my 1976 Grumman Cheetah N9811U.

[[Image:N9811U.jpg]]

We are based in Erie Colorado ([http://www.airnav.com/airport/48V 48V]).

File:N9811U.jpg

2006-03-04T20:19:11Z

Mboyd: Mike & N9811U on the ramp at KSNK.

Mike & N9811U on the ramp at KSNK.

AA5A

2006-03-04T20:08:39Z

Mboyd:

The Annual Inspection

2006-03-04T19:54:11Z

Mboyd: The Annual Inspection

'''Part 1: The Annual inspection'''

My Cheetah is the first airplane I've owned and we just went thru our first annual together. I thought I'd share my experience and I'm also looking for some "sage advice" on what I should expect in an airplanes condition after it has completed an annual. I have found a number of problems since the airplane was returned to service by the shop (which came recommended by a number of individuals as one that knows Grummans...more on that below).

In addition to the basic annual, my squawk list included a throttle cable that was starting to get stiff, a check of the charging system since a battery recently died (it was unknown age and was a really tired battery), replacement of the aileron bearings/bushings as part of the 100 hour AD (recommended from previous AD compliance), and upgrading to the Boom Beam HID landing light (a x-mas gift from my wife - ain't she great). I had also told them I wanted the wobble check done since it had been over 500 hours since the top overhaul. I had taken off 3 days from work in order to "owner assist" (mostly just help with the access panels and watch and learn).

On the first day of the annual, my skills with a Philips head screwdriver served me well as I removed most of the access panels, the wing tips and, with help, the cowl while the A&P spent a fair amount of the time looking at the HID light STC instructions and doing other prep work. We then went to work on the landing gear, finding that new brakes and discs were needed, cleaning and repacking the bearings. I'm thinking at this point that every airplane owner should definitely do this.

Day two was where it got interesting. Brake parts were on back order and most progress seemed to grind to a halt. The A&P decided that the tasks for the day were to install the HID landing light harness/control and replace the wind-sheared ELT antenna. Since the ELT antenna sits partially inside the vertical fin, the A&P decided he'd have to drill out the pop rivets that hold it to the bottom mounting. Since there are screws at the back of the fin and drilling out all those rivets sounded excessive, I asked if he would call Fletchair and see if there was a trick to this. He declined. Of course, after drilling out the rivets and lifting the fin off of the mount he found the clips that would have allowed removal by just removing the screws and sliding forward a few inches (yes *I* later looked this up in *their* copy of the maintenance manual - 53-0 p202). This, along with a prior incident explaining to them how the aileron AD was supposed to be done (Thanks Bob Steward & Barry), and I start to wonder about the "Grumman experience" of this shop.

Since parts were on back order, I went back to my job for a couple days and did not show back up at the shop until the day the parts were supposed to arrive. When I got there, I found that they had "done the rest" of the inspection and replaced most of the access covers and the lower cowl. So much for learning the rest of that process. All that was left was to finish the brake work and install the throttle cable. I was told that they had another plane coming in and needed to get mine wrapped up. So, the A&P finished the work (brakes and throttle cable) and I reinstalled the wheel fairings. I asked about the results of the wobble check and they said they didn't have the fixture but would order one if I wanted to reschedule another appointment. Hmm...I've only had this scheduled with them for over a month and I specifically asked about this check...oh well.

In hindsight I wish I had been there the entire time my plane was at the shop. After the A&P approved the plane for return to service, I found the following squawks that did not exist prior to the annual:

<li>The elevator would stick at about "neutral" - the problem was a interference by a mis-positioned throttle cable clamp.</li>
<li>The elevator would make a noise when full left aileron was applied - A scat tube had moved into the control path.</li>
<li>The flap fuse was blown and replacement caused immediate fuse failure - A&P said he checked the flaps and they were fine, but the limit switches may now be out of adjustment and the mechanism was jammed in
the up position.</li>
<li>The right brake intermittently loses effectiveness - Cured by bleeding the brakes.</li>
<li>The wheels or brakes make rubbing noises as if a brake is sticking a little and the disc is warped. - This turned out to be a problem with how the fairing was installed. Fixed by my *new* shop.</li>
<li>Fuel was leaking out of the carburetor return hose fitting @ ~4gph(1) They rechecked and tightened the fitting.</li>
<li>My Nav2 radio no longer worked – New mechanic found that the plug had been knocked loose. Now fixed.</li>
<li>Trim around the rear seat belt mounts had been broken (yeah, I know a nit pick and brittle plastic - guess I'll try that MEK and dissolved plastic trick I've been reading about. Of course the guys that replaced all the side window plastic a year earlier managed to do it without breaking the plastic)</li>
<li>The updated W&B, required by the STC, was not placed in the plane (only copy was in their file).</li>

(1)This, unfortunately, was discovered in-flight by my fuel totalizer which was showing an unusual 13GPH consumption rate for my HC Cheetah. Looking inside with the electric pump on, there was an obvious stream (fountain?) of 100LL coming from the fitting. I have since modified my pre-flight checklist to include pressurizing the fuel system before the external walkaround and to check for fuel leak/smell around the cowl.

Now, I understand that my Cheetah's 30th birthday is this year and I would expect that things could potentially fail just after an annual. And I know that problems are why we regularly practice emergency procedures. But to have such a large number, and specifically items that they should have inspected or they touched during the course of their work, be problems immediately after the annual seems to be to be outside the range of normal coincidence. I have since received a copy of the checklist they use for annual inspections and have tried to compare it to the one in the maintenance manual. The one they use is a general checklist and so it includes items not on our planes (such as retractable landing gear checks) but does not include items specific to our cats (like skin bonding issues, canopy issues, etc.). And items on their checklist, like "Flight controls free and correct", do not appear to have been performed after all work was completed. I've founds checks in the inspection checklist in the Grumman Maintenance Manual that should have found all the above problems if done in an appropriate sequence.

So I'm now a little concerned that this annual included some pencil-whipping or, at a minimum, was done by an A&PIA that doesn't have a detailed checklist (or a good attention to detail) and isn't very familiar with the aircraft. To their credit, they have been good at working with me to fix the issues.

But like I said, I'm kind of new to this process so I'd like to hear from some of you veteran owners and mechanics out there. On a scale of "Oh, stop your whining" to "Go quickly and find another shop," where do you think this experience belongs?

Next: [[The Replies]]

The Annual Inspection

2006-03-04T19:52:37Z

Mboyd:

'''Part 1: The Annual inspection'''

My Cheetah is the first airplane I've owned and we just went thru our first annual together. I thought I'd share my experience and I'm also looking for some "sage advice" on what I should expect in an airplanes condition after it has completed an annual. I have found a number of problems since the airplane was returned to service by the shop (which came recommended by a number of individuals as one that knows Grummans...more on that below).

In addition to the basic annual, my squawk list included a throttle cable that was starting to get stiff, a check of the charging system since a battery recently died (it was unknown age and was a really tired battery), replacement of the aileron bearings/bushings as part of the 100 hour AD (recommended from previous AD compliance), and upgrading to the Boom Beam HID landing light (a x-mas gift from my wife - ain't she great). I had also told them I wanted the wobble check done since it had been over 500 hours since the top overhaul. I had taken off 3 days from work in order to "owner assist" (mostly just help with the access panels and watch and learn).

On the first day of the annual, my skills with a Philips head screwdriver served me well as I removed most of the access panels, the wing tips and, with help, the cowl while the A&P spent a fair amount of the time looking at the HID light STC instructions and doing other prep work. We then went to work on the landing gear, finding that new brakes and discs were needed, cleaning and repacking the bearings. I'm thinking at this point that every airplane owner should definitely do this.

Day two was where it got interesting. Brake parts were on back order and most progress seemed to grind to a halt. The A&P decided that the tasks for the day were to install the HID landing light harness/control and replace the wind-sheared ELT antenna. Since the ELT antenna sits partially inside the vertical fin, the A&P decided he'd have to drill out the pop rivets that hold it to the bottom mounting. Since there are screws at the back of the fin and drilling out all those rivets sounded excessive, I asked if he would call Fletchair and see if there was a trick to this. He declined. Of course, after drilling out the rivets and lifting the fin off of the mount he found the clips that would have allowed removal by just removing the screws and sliding forward a few inches (yes *I* later looked this up in *their* copy of the maintenance manual - 53-0 p202). This, along with a prior incident explaining to them how the aileron AD was supposed to be done (Thanks Bob Steward & Barry), and I start to wonder about the "Grumman experience" of this shop.

Since parts were on back order, I went back to my job for a couple days and did not show back up at the shop until the day the parts were supposed to arrive. When I got there, I found that they had "done the rest" of the inspection and replaced most of the access covers and the lower cowl. So much for learning the rest of that process. All that was left was to finish the brake work and install the throttle cable. I was told that they had another plane coming in and needed to get mine wrapped up. So, the A&P finished the work (brakes and throttle cable) and I reinstalled the wheel fairings. I asked about the results of the wobble check and they said they didn't have the fixture but would order one if I wanted to reschedule another appointment. Hmm...I've only had this scheduled with them for over a month and I specifically asked about this check...oh well.

In hindsight I wish I had been there the entire time my plane was at the shop. After the A&P approved the plane for return to service, I found the following squawks that did not exist prior to the annual:

<li>The elevator would stick at about "neutral" - the problem was a interference by a mis-positioned throttle cable clamp.</li>
<li>The elevator would make a noise when full left aileron was applied - A scat tube had moved into the control path.</li>
<li>The flap fuse was blown and replacement caused immediate fuse failure - A&P said he checked the flaps and they were fine, but the limit switches may now be out of adjustment and the mechanism was jammed in
the up position.</li>
<li>The right brake intermittently loses effectiveness - Cured by bleeding the brakes.</li>
<li>The wheels or brakes make rubbing noises as if a brake is sticking a little and the disc is warped. - This turned out to be a problem with how the fairing was installed. Fixed by my *new* shop.</li>
<li>Fuel was leaking out of the carburetor return hose fitting @ ~4gph(1) They rechecked and tightened the fitting.</li>
<li>My Nav2 radio no longer worked – New mechanic found that the plug had been knocked loose. Now fixed.</li>
<li>Trim around the rear seat belt mounts had been broken (yeah, I know a nit pick and brittle plastic - guess I'll try that MEK and dissolved plastic trick I've been reading about. Of course the guys that replaced all the side window plastic a year earlier managed to do it without breaking the plastic)</li>
<li>The updated W&B, required by the STC, was not placed in the plane (only copy was in their file).</li>

(1)This, unfortunately, was discovered in-flight by my fuel totalizer which was showing an unusual 13GPH consumption rate for my HC Cheetah. Looking inside with the electric pump on, there was an obvious stream (fountain?) of 100LL coming from the fitting. I have since modified my pre-flight checklist to include pressurizing the fuel system before the external walkaround and to check for fuel leak/smell around the cowl.

Now, I understand that my Cheetah's 30th birthday is this year and I would expect that things could potentially fail just after an annual. And I know that problems are why we regularly practice emergency procedures. But to have such a large number, and specifically items that they should have inspected or they touched during the course of their work, be problems immediately after the annual seems to be to be outside the range of normal coincidence. I have since received a copy of the checklist they use for annual inspections and have tried to compare it to the one in the maintenance manual. The one they use is a general checklist and so it includes items not on our planes (such as retractable landing gear checks) but does not include items specific to our cats (like skin bonding issues, canopy issues, etc.). And items on their checklist, like "Flight controls free and correct", do not appear to have been performed after all work was completed. I've founds checks in the inspection checklist in the Grumman Maintenance Manual that should have found all the above problems if done in an appropriate sequence.

So I'm now a little concerned that this annual included some pencil-whipping or, at a minimum, was done by an A&PIA that doesn't have a detailed checklist (or a good attention to detail) and isn't very familiar with the aircraft. To their credit, they have been good at working with me to fix the issues.

But like I said, I'm kind of new to this process so I'd like to hear from some of you veteran owners and mechanics out there. On a scale of "Oh, stop your whining" to "Go quickly and find another shop," where do you think this experience belongs?

Next:[[The Replies]]

The Replies

2006-03-04T19:51:04Z

Mboyd:

'''Part 2: Replies'''

Needless to say, the general consensus was that, while this may not be uncommon, it is definitely unsatisfactory performance for an Annual Inspection. I received a number of responses with specific mechanic recommendations, and expressing their sympathy. I did not want to reproduce all of them here, but I do appreciate them.

Since the original posting, I have found another shop. Below are excerpts of some of the responses that helped me with that decision. (If you wish for me to remove your response for any reason, please let me know):

Andy:
There are about 6 or 7 true Grumman gurus in the country and if you don't go to one of them you are pretty much going to be in charge of quality control....my solution is to work with the mechanics as much as I can during the inspection, accept whatever comes out so long as the paper work is correct and get a guru to do the inspection every few cycles.

Ed:
...You don't necessarily need a "guru" to do a good job. I'd rather have an honest, hardworking, meticulous A&P/AI that has limited Grumman experience work on my plane...If you have a good idea about the "special" areas to look out for (for example, SAIB on the tail bulkheads/stiffeners, Front gear service, delamination, aileron bearing wear, fuel tank leaks, corrosion on the main wing spar as viewed from the landing gear root area and also from the seat area, torque tube condition, slight lifting of cowling doors in flight, baffle/cooling dynamics, oil cooler mount cracking, throttle linkage integrity, and I am sure there are others I am missing) and tune your mechanic in to them then you're just about covered. After all, these planes are much easier (as in not harder) to figure out and maintain than a Cessna or Piper because they are so much simpler.

Steve:
I think you did all the right things in trying to be there for the annual. I think we all would fly and feel safer if we could be at those once a year events. You should have a copy of the maintenance manual with you at all times at an annual. Insist that the A&P follow it as close as possible and practical. The sqwaks you mentioned should never have happened.

And, of course, there were many people that included comments like the following from Dave:
I believe there is nobody better than Bob Steward [or Cliff, Barry, Ron, etc.], both in knowledge and performance. I feel like I owe him a couple of kilobucks just for the knowledge gained and pain avoided from reading his posts and personal replies.

(Just so you Guru's out there know that the rest of us that are just learning about these fine airplanes appreciate your, sometimes often repeated, advice and understanding!)

Next: [[What I've Learned]]

What I've Learned

2006-03-04T19:46:56Z

Mboyd:

'''Part 3: What I've Learned'''

Since my original post, what I found out was that this shop lost all the A&P's that they had just a couple years ago (same owners though) and the one they have now seems to have an attention to detail problem (definitely a bad thing for an A&P IA) and doesn't tend to read the maintenance manuals that the shop provides for him. As I recall, one of my responses to a private e-mail sent after my original post included the phrase "You can lead an A&P to the Grumman manual, but you can't make him read it" and that seems to sum it up.

I'm now using the "other" mechanic on my home field and am much happier with their performance. Although they have more experience with those C model aircraft, they are detail oriented and appear to be much more capable than the first shop (I interviewed the owner and the head mechanic for about an hour each). They have fixed many of the problems caused by the first annual and have not caused any additional ones (definitely a step in the right direction).

Here's what I've learned from this experience:
<li> Do your homework. I can't emphasize this enough. If you are reading this, you are probably well on your way to doing that. Find out what to expect from a pre-buy or annual inspection (get the checklists from the maintenance manual, etc). Interview potential mechanics and get references. Talk to other pilots in your area.</li>
<li> Find a "good" mechanic. Choose a detail-oriented mechanic. A good mechanic that doesn't have as much experience with Grummans is much better than the inverse. Beware of high turn-over rates of mechanics at a given shop (seeing lots of new faces and no old ones at your favorite shop?)</li>
<li> Be an active participant in your airplane care. Be there for pre-purchase inspections, annuals, etc. Using that homework you can follow along with the mechanic and ask questions. If your mechanic will allow, "owner-assist" on the work. One of the mistakes I made during the annual was that I was not there the entire time. Until you are intimately comfortable with the mechanics work, be there.</li>
<li> If it doesn't "feel right" it probably isn't. Be it the mechanic, a problem with the plane, an explanation, etc. My "normal brake noise" after installation of new brakes & rotors ended up being a mis-installed wheel fairing. Go with your gut instincts.</li>
<li> Know where to go to get answers. The Grumman gang mailing list is an excellent resource and monitored by some very savvy A&P's. The folks at FletchAir, and this site are all good references.</li>
<li> Learn from your experiences. I know it's kinda obvious, but it needs to be said. Adding a fuel line pressurization check to my pre-flight checklist, for example.</li>

Well, I hope that this story has been helpful. Take care and safe and happy flying!

--Mike