The same thing happened to me about 4 years ago with my Hanger 9 Fokker DVII. If you are using digital servo's, it is normal to have them bounce around because they are always trying to find dead center electronicly.

When it happened to me, I noticed that my Y-harness was pinched between the back part of the glow tank and a wooden truss I had putting pressure on the tank to keep it forward. Every time I throttled up, the servo's went crazy, then when I throttled down about half throttle it'd stop. It drove me crazy! I knew the vibration was causing problem, but I didn't have a clue!


Once I found the culprit of the problem, I changed the Y-harness with a brand new one and made sure none of my wires were pinched. I've been flying the same plane for 4 years now with no problems. I also check the balance on my prop to lesson the vibration.

Hope I helped,


Pete