Instrumentation

DRAFT NEW PAGE - Gil Alexander

Items needed but not supplied...

1. #8 wire gauge ring terminals with 1/4 inch hole (instructions say to just use existing wiring, but my plane - 77 Tiger - used 3/16 terminals on the power wiring to the old ammeter, and the new shunt has 1/4 inch threaded terminals)

2. New hoses to senders - I used new AN-4 firesleeved hoses - 10.5 inches for fuel pressure and 18 inches for oil pressure - but 16 inch would probably be better - see later pics.

3. Clamps to mount the senders, 5/8 for the engine mount side and 1 9/16 for the two senders. Instructions call for all clamps to be cushioned MS21919, however the oil pressure sender does not have a ground connection, and cushioned clamps do a good job of electrical isolation. Since my supply house did not have 1 9/16 plain clamps, I found that a 1 7/16 cushioned clamp with the rubber removed worked well. The AN3 bolt that is used to connect the small and large clamps can be used as a ground point for this sensor. The installation instructions ignore this....

3. Usual assortment of #20 aircraft wire and good quality ring terminals and splices.

4. You need to splice 3 or 4 wires into a single wire in four places, I found that soldering and a good quality heat shrink worked well. Check with your A&P on this and do what he/she prefers.

5. Rubber "booties" to protect the exposed hot wires (when the Master is ON) on the ammeter shunt - not essential, but a nice safety feature to have - MS25171-1 (2).

6. AN929-4D caps (2)- to seal off the old fittings that penetrated the firewall.

7. AN910-1D couplings (2) and AN816-4D (2) pipe thread to flare fitting to connect the sensors to the hoses.

Wiring the gauges

The gauges need quite a bit of work wiring before any installation occurs. Since each gauge is a separate module, all of the common wiring (power, grounds, lighting) need to be connected together. This is how I did it.... top of module is on the left.

When this package wiring is completed, you should have ends for - two red wires to the ammeter shunt - two ground wires, meter ground and lights ground - a lighting power connection - a hot 12 volt connection (direct to bus, not through an Avionics switch), fused or breakered - and finally three sensor wires.

I chose to get power from a new 1 Amp breaker, since I had to add one for the Horizon tachometer I am adding at the same time. It was easy to just make it two new breakers. I placed them side by side under the new instrument stack. The STC says to use the power wire that was connected to the origial instruments - via the fuse shared with the strobes.

<still in progress...>