Jumpy/intermittent trim indication

[DaleB]

The trim indication in our RV-12 is intermittent and jumpy. Sometimes it indicates correctly, mostly not. I'm going to chase the wiring to make sure it's not a flaky connector pin, but I don't think it is -- this has been an occasional issue for the past couple of years, and recently just got a lot worse. Has anyone had one of the Ray Allen trim servos apart to clean or repair the position indicator pot? Is this a common or known issue?

[lr172]

I have not had one apart, but I would assume the internal pot is bad and not just requiring a cleaning. I would speculate that it uses as traditional sealed pot and not a wiper arrangement.

You just don't hear about that problem much, so I assume they are pretty solid. I would definately start with wiring, especially the ground and connectors. It doesn't take much resistance change to make the indication bounce around. I have a custom flap indicator setup and the original cheap pot starteg going bad and gave similar symptoms.

Larry

[olyolson]

Dale,

I don't know what trim indicator you have in the RV-12. It may be internal to an EFIS or maybe the older individual Ray Allen trim indicators like I had for the elevator & aileron trim. My elevator trim indicator was inop and the aileron trim indicator was only lighting up half the lights and jumping around intermittently. The trim in both directions appeared to be working just fine. I replaced both with the newer color LED RP4 trim indicators and now both trim indicators are working fine. It was an easy swap, the older wires are colored striped and the newer wiring is solid colors. Just wire the striped colored wires from the plane to the same solid color on the newer indicators and label as required.

Don't know if this helps as I am unfamiliar with the RV-12.

Here's what they look like and are available at Acft Spruce or direct from Ray Allen:

[DaleB]

The -12 uses a display widget on the EFIS.

[olyolson]

Ok never mind......