rathmn

I have a GP 60. UCD and I am having some trouble with digital servo jitter. I have the Futaba 7c w/ 617 reciever. The servo's I am have trouble with are a futaba 9151 and 9250. I had aprox 10 flights on the airplane and one day after landing and engine shutdown I heard what sounded like a motor running. I looked back at the tail and one half of my elevator was buzzing like crazy. I got it to stop but full scale back to center with the stick would make it vibrate agian. It is like the servo is trying to center itself but it can't. I also had some trouble with the rudder servo but it is not as bad. I am running heavy duty 24" servo extensions. I also have heavy duty servo arms with 4-40 hardware. There is very little slack in the linkages. Anybody have any ideas on how to stop this. I shortened up the throws and that helped a little bit. However, I would think I should be able to run full throws and not have a problem. If you have any thoughts please let me know.

Rodney

If the elevators are not mass balanced and you have nice free hinges, when just sitting, the elevator weight pulls it down and the servo brings it back up and relaxes, elevator falls again, servo brings it back up. If that is the problem, then just mass balance the elevators. I've seen this happen with ailerons also when each aileron has it's own servo.

Gray Beard

My Feedback: (-1)

Rodney, that was one great answer!!!!! I have chased down this problem a few times but never gave the why of it very much thought. Thanks, I learned something before my second cup of coffee!!!

rathmn

That could be the problem. The hinges are very free. I will give it a try and let you know.

Thanks!