Elevator trim issue

[tkatc]

My elevator trim is intermittent but only in one direction. I have Ray Allen grips and suspected the button on the grip but I also have a back up rocker switch on the panel. When it doesn't work, it doesn't work on either switch. I suppose that points toward the servo itself?

It is a very annoying issue. I am reluctant to even use trim because if I trim it in one direction, and it won't go in the reverse direction, I will have to muscle up on the stick for the remainder of the flight. I have found that if it doesn't work, a small bump in the opposite direction will wake it up and it will function normally. Any ideas what this problem is or what I should inspect?

[db1yg]

Do you have the rel 1 relay? I had the same symptoms and the relay was going bad. Ray Allen has since replaced the rel 1 with a more robust unit---the rel 2. If this is the problem they will discount the price 50 per cent for the new unit.

Hope this helps.

Cheers,

db

[tkatc]

Hmm, not sure which relay I have. I will have to look. How is it identified?

[scard]

It is very, very likely the relay. Many of us have experienced the same thing.

[RV8Squaz]

I had the same trouble. The old relay looks like a small matchbook, about half inch by one inch by 1/8" high. The new one is a 1" cube. If you have more than one old relay, replace the others too before they fail, because they will.

Jerry RV-8 N84JE

[scard]

Originally Posted by RV8Squaz

I had the same trouble. The old relay looks like a small matchbook, about half inch by one inch by 1/8" high. The new one is a 1" cube. If you have more than one old relay, replace the others too before they fail, because they will.

Jerry RV-8 N84JE

I totally concur, when in doubt, rip 'em out.

[tkatc]

Now I just have to find my relay. Since I only have elevator trim, is it safe to assume I only have one relay? Or since I have a switch on the pilot's grip and another switch on the panel, might I have 2 relays? Not sure how these get wired up yet. Thanks for helping me be lazy!

[F1R]

One only if you have elevator trim and no roll trim.

[pierre smith]

Tony, both my -6A and -10 had relays replaced...exact same symptoms as yours.

If you'll turn the master on and intermittently push the trim button, you should hear it click, click, click and help you find it. Chances are, it's under the seats. Can you call the previous owner or builder?

Best,

[Pat Hatch]

Originally Posted by tkatc

Now I just have to find my relay. Since I only have elevator trim, is it safe to assume I only have one relay? Or since I have a switch on the pilot's grip and another switch on the panel, might I have 2 relays? Not sure how these get wired up yet. Thanks for helping me be lazy!

It would be helpful if you could get a schematic from the builder otherwise you are probably going to have to go through the wiring and reverse engineer a schematic. Which Ray Allen grip do you have? The switch in your panel sounds like his DPDT switch which doesn't normally need a relay. Some of his grips are also set up DPDT. You only need a relay to convert from SPDT to DPDT, or if you want to have two separate switches controlling the same trim servo. Or there could be a selector switch between the panel switch and the stick grip. Sounds like you don't have the selector switch so you probably have some kind of relay set up. The relays come single, dual or 3-channel. One channel is actually two relays, so it can get confusing. Normally, for just elevator trim you would need a 1-channel relay (which is actually two relays wired together).

If you decide to rip everything out and start over, you might take a look at the relay panels that I sell that incorporate D-sub connectors. These are also hubs for all the grip functions such as your PTT switch or any other buttons that you might have on your grip. If you are interested drop me a PM and I can send you some schematics and more info on my relays. Check them out here:

http://www.vansairforce.com/communit...ad.php?t=83609