Stuck Trim Tab

[rdockery_3]

My 2011 RV12 trim button isn't working. I went out to the plane this morning and after I started the engine and was going through my checklist my trim stabilator trim wouldn't work. I shut the engine off and kept pushing the button and there was nothing. I couldn't hear any sound coming from the servo or anything. I took the cover off and didn't see anything disconnected. My next step was going to be looking behind the instrument panel but I wiggled the switch a little bit and it started working. So, I thought I had found my problem, I figured it was a loose connection on the switch. Then it quit working again. You can hear the servo now when you push the switch but there is no movement. I'm still going to look behind the panel to see but i don't think it's a loose connection because the servo is obviously getting power. Any troubleshooting help would be helpful.

 

[Piper J3]

The switch is directly soldered to the main circuit board. It is possible to replace. Search VAF for switch replacement PN. FWIW.... I asked ChatGPT for switch PN and was given OTTO Controls P/N K2ABMAAAAA.

 

[Tony_T]

The switch is directly soldered to the main circuit board. It is possible to replace. Search VAF for switch replacement PN. FWIW.... I asked ChatGPT for switch PN and was given OTTO Controls P/N K2ABMAAAAA.

Rdockery:
Before doing open heart surgery on the board, I recommend more research. In case you are not the original builder; there was a Safety Directive (SD-00001) issued by Van's aircraft in 2020, regarding inspection and replacement of the trim servo. Also, it is possible to run the trim servo with a 9 volt battery to determine if the servo is INOP, or if the problem is actually with the trim switch or wiring.

 

[seagull]

The trim switch applies a “ground” signal. The center contact is grounded. When you toggle the switch the ground is applied to either outside connection. You can jumper the switch with no fear of burning up anything.
The trim servo motor in the back is a small cheap 12 volt brushed motor with a gear train. The motor changes direction depending on the polarity of the input voltage. They are rated at well over 1000 hours so it’s possible but unlikely that it is the motor.

 

[rdockery_3]

Do you guys think it would be the switch if the servo is making noise when you push the switch though? When I push the switch the servo sounds like it is trying to work but it's almost like it's in a bind. I am not the original builder and after researching that service bulletin I'm leaning toward that being the problem, but I'm new to plane ownership so I'm new any advice. Here in a few days when I have more time to look at it I'm going take the panels off again and take a more in depth look at the servo. What should I be looking for when it comes to that service bulletin?