Trim Malfunction

[av8reb]

My RV12 trim’s up but will not trim nose down with either stick pickle switch. Fuse is ok, just wondering if anyone else has had this problem and what was the fix. Thx
Keep’em flying

 

[rcarsey]

I'd first check the wires at the connector in the tailcone fairing. the wires coming out of the servo itself are very thin and may have broken.

 

[Tony_T]

While back at the trim servo you can easily check the trim servo itself with a 9 volt battery.

 

[AZSteve053]

My RV12 trim’s up but will not trim nose down with either stick pickle switch. Fuse is ok, just wondering if anyone else has had this problem and what was the fix. Thx
Keep’em flying

I am unfamiliar with the RV12 provided avionics setup, including pitch trim controls HOWEVER most twin stick aircraft having Elect trim switches on the stick utilize a trim controller of some sort that arbitrates control of the trim servo preventing Pilot from commanding UP while Copilot is commanding DN - this is done with relays. The Trim servo is simply a DC motor, trim direction is typically just swapping the two wires - also done via the relay controller. My thoughts: If the trim UP works but Down does not - the problem lies with the controller relay logic. In Advanced Flight EFIS systems (& some Dynon) such as AF5600 AND equipped with an AP control panel - this controller function is built-in to the AP control panel AND include trim speed scheduling AND stuck switch limiting to 3 seconds of constant operation (trim run away).
Hope this helps, for more help - tell us more about your avionics suit etc.