This is an old topic, however I would like to point out what I have experienced. After my first flight in N12YR (July 2012), I had a heavy left wing. After searching our database there were all kinds of fixes and I tried several of them. My final, easy, and corrective fix was to replace the control linkage on the servo that I purchased from Glasair Aviation. First I made an adjustable pushrod using all-thread rod and screw on clevises. Later, I remember the pushrod on our elevator trim. So I installed the adjustable RC8-7 Clevis/Pushrod kit that I purchased from Aircraft Spruce. The RC8 is the same pushrod that we installed on our elevator trim.
This adjustable pushrod lets you make adjustments to the servo’s up and down fixed position. The pushrod that came with the Glasair servo kit was fixed (cheap). It would be real luck if you happen to get it correct before flying. After installing the new adjustable pushrod, I made a test flight and I still had a heavy left wing. For starters, I had made the new pushrod length the same as the old fixed pushrod. I think I made 2 more test flights and adjustments before getting it right. I now have a ground adjustable aileron trim tab. I don’t know if the current servo kit still comes with the fixed pushrod or not.
The reason I am writing this heads-up today is because I just read the same thing in the February 2014 issue of the Kitplanes magazine. The article is titled The Truth About Trimtabs on page 77. In the article the author says “a servo-tab can also be made to serve as a trim tab.” I guess that is what I did. This is a very good article, check it out. I especially like his comments about reducing drag.
Ed. note: the instructions for the factory servo tab kit are available in the library.