Advice on troubleshooting electric trim switch

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perossichi
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Advice on troubleshooting electric trim switch

Post by perossichi »

For some time now, the electric trim switch on the pilot's stick doesn't work in my 2002. The electric trim works fine when the autopilot uses it. I'm so used to using the trim wheel that I hardly pay attention but I thought I should get this fixed in the event that I want to sell the plane.

Any thoughts on troubleshooting this? Should I just order a new switch and try this?

thanks in advance!

peter r
Sold 2002. Powerflo, Hartzell composite two blade, 530W/430, 345 transponder.
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Steve
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Re: Advice on troubleshooting electric trim switch

Post by Steve »

perossichi wrote: Tue Jul 13, 2021 12:39 amShould I just order a new switch and try this?
Have you priced the trim switch assembly? It is stupid expensive. You (or the Hangar Fairy) might be able to remove the assembly and source the microswitches (there are 3 if memory serves correctly) individually. I got a good deal on a new switch assembly to hold in reserve for my aircraft on eBay about 15 years ago, anticipating that it could fail in the future, but so far it is good.

Steve
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Rich
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Re: Advice on troubleshooting electric trim switch

Post by Rich »

The first thing I'd do is check the connector for the stick harness. I believe it's below the pilot seat. Using an ohmmeter check whether operating the switches produces the correct responses between pins 4 and, individually, pins 1,2,3 (See AMM wiring diagram DA4-9222-10-03). That will tell you whether it's in the components in the stick (switch, wiring) and which one. If you find it is, pull the switch and check continuity of the wires beteen the connector and the errant switch. Failure of the wire to either pin 3 or 4 of the connector would be enough to prevent the operation of the trim.

You could also check for physical inhibition of the switch operators, especially the "arm" operator. These things are inherently stiff and dust, lint, or whatever could keep them from proper movement.
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
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