Electric Elevator Trim Questions

First the problem, then the questions. A previous owner of my RV3 replaced the manual elevator trim with electric - the servo is located under the vertical stab, controlled by a rocker switch in the cockpit. Looks like the typical installation, and works well when it works. But it periodically stops working in one direction - it will trim nose down but not nose up. My solution so far is to remove the servo lid, rotate the gears with my finger (they turn easily), and it starts working again for a while.

My questions:
Is a wiring schematic for the trim system available somewhere? I'd like to check the electrical continuity/operation.

Should the gears be lubed (assuming the problem may be binding gears)? If so, what should I use?

Thanks for your help.

Joe Lofton

Ray Allen Company

You undoubtedly have a Ray Allen Co. trim system in your -3. These are the folks you want to talk to - here's a link to their wiring diagrams and install info:

http://www.rayallencompany.com/RACinfo/downloadpg.html

Fixed for Now

Thanks, Rob. I printed off the connection diagram and took it to the hangar. Tried the trim and it had not fixed itself overnight. Took off the fairing, loosened one screw in the servo lid, and for some reason tried the trim again - it worked!

Looks like maybe the little metal gizmo that moves back and forth to operate the microswitches was binding on the side of the housing. I gave it a gentle squeeze with a pair of pliers for better alignment, put on a thin film of liquid Boelube, and buttoned everything back up. I'll see if that was the fix.

Still don't know who made the servo - it is in a black plastic box without any markings (unless they're on the bottom).

...Joe Lofton

Joe,

Mine is all buttoned up, but if I recall correctly the Ray Allen servos are devoid of much marking at all. They are indeed little black impact plastic boxes and that's what Van's sells and most everyone uses for electric trim. It would be unlikley if it were anything else.

You may also want to follow the wiring harness to make sure that any connectors are secure and that you don't have a wiring coming out anywhere - also up at the panel on the trim indicator or switch(es) as well.

Hope you find your electrical devil.

-Rob