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Elevator Trim Issue

Robb

Well Known Member
My F1 is having an intermittent issue with the elevator trim. It works fine when switching it to nose down trim but is intermittently not moving in the nose up position. I have Infinity stick grips and I suspect it is either the switch or relay board. Mine has the little round knob on the stick for the trim adjustment. Does anybody know the part number for the switch? I also need to find out where the relay board is located. Is it near the actuator motor?
 
By "round knob", are you talking about the "coolie-hat" 5-way switch?

If so, it sounds like you might have the Infinity stick grip. You might need to go to the Infinity website and get in touch with them about the replacement switch part no.

As far as trouble-shooting your gripe, have looked at the trim rigging. That little trim servo control linkage can get pretty fussy if not rigged properly. And, there's some nylon parts that can wear/flex as a result, causing weird gripes with flight loads on the control surface.
 
I had a problem with a bad connector back by the servo. It would work most of the time, then just randomly stop working, and only in the air (always worked great on the ground). Intermittent electrical issues are the hardest to find.

The relay board is most likely under the seat somewhere. Get out your multimeter and work from the switch back.
 
Thanks Guys. I need to get a helper and a meter and start tracing voltage. Im not the builder and not sure where the relay board is but Ill find oot. Didnt dee it during the conditional
 
What trim controller?

There have been several trim controllers used over the years. - know your controller brand and how it operates
Initially I thought I had a wiring, switch or relay issue but it turned out to be a finger problem where the controller got into programming mode un knowingly and then reprogrammed to zero speed for pitch just by trying to operate the coolie hat switch. Mine has a programable pitch trim speed for reduced trim speed in flight vs rapid trim speed for flaps down trimming. (turning the master on with the trim hat activated puts the controller into programming mode)
In a quiet hangar with flaps down trim was normal , however flaps up the trim servo would only groan / buzz with no actuation.
That took a while to diagnose but it was a very easy fix. I did need to learn the programming code and the actual speed is set by the trim switch on the stick and counting led flashes.
Your builders wiring diagram should help ID the controller, then find a manual for the controller.


Normally I leave the pitch trim set for solo cruise flight. For landing I just hold the pressure (nose heavy). The only time I normally re trim is when I have a passenger.
 
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Robb,

Can you let me know how this resolved? I have an identical problem on a recently purchased RV-7 with an Infinity coolie hat, and want to know if the switch, cable connections, or the board turned out to be the problem. Kind of hoping its the switch, as I have a new one enroute, and the flap switch is loose in the grip too, so I'll need to do some work on it regardless. Thanks.
 
If anyone having this problem is using the Van’s wiring kit (the one with the tiny micro Molex plug at the servo), I suggest you start there.

I chased my tail for two days helping with an RV-14A build. This connector was the problem.

Carl
 
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