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aileron trim problem

barneylocke

barneylocke

I'm New Here
Help! Our -8 requires full left aileron trim for TO and climb. Its flies fine at cruise with neutral trim but then requires full right trim during decent. Any ideas why this is so and any suggestions on fixing it? Thanks
 
Welcome to VAF!

Barney, welcome aboard the good ship VAF.

What are you doing with the rudder, and where is the ball during climb and decent??
 
Mike..thanks for your replies. Yes we have both pants and fairings installed. We are going to start by replacing the aileron trim springs however the factory rep said he doubted that was the problem. We did check the rigging of the elevator which was right on....
 
What speed are you flying? If climb is slowest and descent is fastest, you are probably just seeing normal behavior of a spring bias trim system compensating for a heavy wing. You might do a test flight without the springs, and see how it flies.

Paige
 
PaigeHoffart said:
What speed are you flying? If climb is slowest and descent is fastest, you are probably just seeing normal behavior of a spring bias trim system compensating for a heavy wing. You might do a test flight without the springs, and see how it flies.

Paige
Click to expand...

I agree.

Also use section 5.7 of THIS document, to check the shape and adjust both of the ailerons (check the elevators and rudder while you are at it). Doing that will likely resolve most if not all of your problem.
 
we'll try that

Gentlemen, Thanks for the tip. One of the partners had the same idea. We'll try it this week and let you know. Climbing at 70 to 110K and descent at 150K...are you saying this is normal for an RV? We've bought new springs and were also going to try and replace the old ones....
 
barneylocke said:
Gentlemen, Thanks for the tip. One of the partners had the same idea. We'll try it this week and let you know. Climbing at 70 to 110K and descent at 150K...are you saying this is normal for an RV? We've bought new springs and were also going to try and replace the old ones....
Click to expand...

Replacing the springs might improve the performance of the roll trim, but it wont do anything to correct the roll imbalance you have with changes in speed.
That has to be resolved separately first.
The part that I agreed with in my previous quoted post (but it may not have been clear) was that you should disconnect the trim system and find the cause of the imbalance and fix that first. Then get the trim system working properly.
 
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