Aileron trim tension

[Gordona23]

My RV-9A has a slightly heavy left wing. I applied full right trim and it had no effect. Since I did not build the airplane, I can't be sure the trim was
set up properly so, after verifying that the servo was indeed moving, I removed the springs. and replaced the seat pan. As soon as I get flyable weather,
I'll find out how much of a rigging problem I have, and deal with it. But clearly, there's something wrong with the trim system. Can anyone who has a
properly working version of this system give me an idea of how much force the springs should put on the stick. If anyone is really bored (or really helpful), a
fish scale pull at some measured distance above the seat pan, with the trim set at full right or full left, would be very helpful. Thanks.

 

[bruceh]

I had to add a 5" wedge under my right aileron to correct the heavy left wing on my RV-9A. I tried just about everything else with the hinge positions to no avail.
On the trim springs, just make sure they are both equal length and tension at the neutral trim position. I fixed one airplane that had unequal links on the trim arm. One side always had way more tension than the other.

 

[rvbuilder2002]

I had to add a 5" wedge under my right aileron to correct the heavy left wing on my RV-9A. I tried just about everything else with the hinge positions to no avail.
On the trim springs, just make sure they are both equal length and tension at the neutral trim position. I fixed one airplane that had unequal links on the trim arm. One side always had way more tension than the other.

Previous thread on the subject.

Electric Aileron Trim spring tesnsion?

Hi all, I had to pull my seat pans this weekend to fix a bad BNC and installed the springs/safety wire to my already installed aileron trim servo. Nothing in OP19/instructions were super clear on the amount of pre-tesnsion so I put both springs in just slight tension when the sticks were...

vansairforce.net

 

[lr172]

Scott posted some great advice in the thread he referenced. However, if you don't know or trust what you have, my recommendation is to disconnect both springs and go fly. Observe how much heavy wing you really have. If it is significant, then do some research here on how to a address that. Once that is all sorted out, then follow Scotts advice to connect your trim back up correctly. Using aggressive trim spring compensation is not a good way to deal with a heavy wing.

Larry

 

[Tankerpilot75]

I had to add a 5" wedge under my right aileron to correct the heavy left wing on my RV-9A. I tried just about everything else with the hinge positions to no avail.
On the trim springs, just make sure they are both equal length and tension at the neutral trim position. I fixed one airplane that had unequal links on the trim arm. One side always had way more tension than the other.

+1

If you fly solo more than with someone in the right seat then you’ll definitely want to consider adding a trim tab. But you need to insure the aileron tension spring is correctly setup so that you can get the maximum aileron trim that the plane can provide.

 

[PilotjohnS]

I had to add a 5" wedge under my right aileron to correct the heavy left wing on my RV-9A. I tried just about everything else with the hinge positions to no avail.
On the trim springs, just make sure they are both equal length and tension at the neutral trim position. I fixed one airplane that had unequal links on the trim arm. One side always had way more tension than the other.

To expand of what Bruce said, I changed my web to a 032" gurney flap. it is 1/2 the size of my old wedge. For best effect, It must be placed with with the "L" part even with the trailing edge. If the "L" part is forward of the trailing edge, it is not as effective. I find the Gurney flap is smaller and less obtrusive than a wedge. YMMV

 

[PilotjohnS]

+1

If you fly solo more than with someone in the right seat then you’ll definitely want to consider adding a trim tab. But you need to insure the aileron tension spring is correctly setup so that you can get the maximum aileron trim that the plane can provide.

My spring tension is such that at full deflection, the "slack " spring is barely under tension. Next time, it will be a trim tab built into one aileron. Next time.

 

[rvbuilder2002]

Scott posted some great advice in the thread he referenced. However, if you don't know or trust what you have, my recommendation is to disconnect both springs and go fly. Observe how much heavy wing you really have. If it is significant, then do some research here on how to a address that. Once that is all sorted out, then follow Scotts advice to connect your trim back up correctly. Using aggressive trim spring compensation is not a good way to deal with a heavy wing.

Larry

I agree with Larry.
Best practice is to correct whatever trim issue exists, while being sure take into consideration whether the opposite seat is empty or not.
I do believe it’s acceptable to use aileron trim to trim out a minor roll imbalance that is a result of airplane build, but anything more than that and you should look at solving the root cause first.