Structural Repair: Difference between revisions

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Somehow the link to the major structural repair was removed. Added it back.
 
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'''Structural Repairs'''
== Introduction ==


The maintenance manual has an extensive collection of structural repair details.  Many cover "Grumman only" procedures like splicing the firewall and cabin floor with a factory repair section, or replacing the entire tailcone from the honeycomb aft.
The maintenance manual has an extensive collection of structural repair details.  Many cover "Grumman only" procedures like splicing the firewall and cabin floor with a factory repair section, or replacing the entire tailcone from the honeycomb aft.
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There are also numerous factory repairs for mistakes made on the factory floor.  These can be very helpful in the field to repair worn and damaged components.
There are also numerous factory repairs for mistakes made on the factory floor.  These can be very helpful in the field to repair worn and damaged components.


The factory also published Service Kit 125A instructions which are the basis for repair of any debonded joint on the plane.  The original need was because of the problems with debonding early on from the "purple glue", but there are other debonding and repair issues that can be addressed with the factory supplied data.
The factory also published Service Kit 125A instructions which are the basis for repair of any debonded joint on the plane.  The original need was because of the problems with debonding early-on from the "purple glue", but there are other debonding and repair issues that can be addressed with the factory supplied data.


Because of the relatively unique construction of the Grummans, most shops are not familiar with repairs to honeycomb and bonded structures.  A considerable amount of material has been added to [http://www.airweb.faa.gov/Regulatory_and_Guidance_Library%5CrgAdvisoryCircular.nsf/0/99C827DB9BAAC81B86256B4500596C4E?OpenDocument AC 43.13-1B Change 1], that deals with bonded and honeycomb repairs.
Because of the relatively unique construction of the Grummans, most shops are not familiar with repairs to honeycomb and bonded structures.  A considerable amount of material has been added to [http://www.airweb.faa.gov/Regulatory_and_Guidance_Library%5CrgAdvisoryCircular.nsf/0/99C827DB9BAAC81B86256B4500596C4E?OpenDocument AC 43.13-1B Change 1], that deals with bonded and honeycomb repairs.


'''Lower Cowling split'''
== Common Structural Repairs ==


Requests for information on splitting the lower cowl on Tigers and Cheetahs was made on the GG and I'll post some pictures and an explanation of the means I used to repair lower cowls that had failed the spot welds and had cracking doublers.
* [[Repair of Debonding]]
* [[Lower Cowling Split]]


Here is the Tiger lower cowl with failed spot welds and cracked doublers after removing the cowl from the plane and taking the doublers out. [[Image:Bottom_sm.jpg]]
== Major Structural Repairs ==


This is a Cheetah LH lower cowl from the outside with larger ramp being drilled and clecoed in place.  Paint is off because of the amount of metal work that was needed [http://www.tinmantech.com/html/powerhouse_wheeling_machines.php with an English Wheel] to smooth the ripples that had been filled with bondo during previous work by persons unknown (no log entry!).
* [[An_Example_Repair|An Example Repair - Cheetah Horizontal stab]]


[[Image:LH_Cowl.jpg]]
== Other ==


Here is the inside of that same Cheetah lower cowl half with the ramp in place and the new doubler mounted, ready to attach the other side with screws.
* [[Tail Tiedown Repair]]
 
[[Image:Left_inside.jpg]]
 
<To be continued>
 
''Gil Alexander''  - I took a slightly different approach for a Tiger repair since I didn't want to harm a new paint job.  I left the doubler in place and added a 0.032 strip of aluminum 1 7/8 wide on the inside.  I removed the nut plate at the front on the nose gear boot mount, and clamped the strip in place.  I drilled #30 holes from the outside where I wanted the mounting screws - in my case somewhat already located by previous repair rivets that I removed - clecoing as I progressed. Matched #19 holes for #8 screws were drilled for the aft screw at the nose gear boot mount and for the central retaining screw into the nose bowl.  The strip was then removed, all holes - cowling and new strip - drilled out to #19 for #8 screws and nutplates riveted to the new strip.  Only now, after the cowling is completey drilled is the original joining strip cut down the middle with a [http://www.hobbypeople.net/gallery/516443.asp 2 inch cutting wheel on a Dremel tool].  If you work from the inside, this can be done without harming the (new) exterior paint.  The only portion of the original joining strip that needs to be removed is the forward 2 inches - this ensured that the extra layer of the new joining strip does not create an extra layer at the center where the cowling is screwed to the nose bowl.
 
''<picture to follow>''

Latest revision as of 09:22, 17 May 2008

Introduction

The maintenance manual has an extensive collection of structural repair details. Many cover "Grumman only" procedures like splicing the firewall and cabin floor with a factory repair section, or replacing the entire tailcone from the honeycomb aft.

There are also numerous factory repairs for mistakes made on the factory floor. These can be very helpful in the field to repair worn and damaged components.

The factory also published Service Kit 125A instructions which are the basis for repair of any debonded joint on the plane. The original need was because of the problems with debonding early-on from the "purple glue", but there are other debonding and repair issues that can be addressed with the factory supplied data.

Because of the relatively unique construction of the Grummans, most shops are not familiar with repairs to honeycomb and bonded structures. A considerable amount of material has been added to AC 43.13-1B Change 1, that deals with bonded and honeycomb repairs.

Common Structural Repairs

Major Structural Repairs

Other

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