Servo noises?
 

I recently replaced all the aileron hinges on my WM extra 300s, but when I hooked the servos back up the right hand servo is making a loud clunk as is moves off centre. The model is powered by a Zenoah G38 so vibration is higher than normal glow planes. The servo is a standard hitec digital with karbonite gears, so I'm thinking that mybe the servo has lost a couple of teeth on the gears and is catching. I also checked the surface is free to move without the servo attached, which it is. I then moved the servo without the surface attached and the clunk is still there. Should I replace the servo?

RE: Servo noises?
 

I'd at least take it apart and inspect it. You should be able to purchase a gear set, if need be.

RE: Servo noises?
 

You might want to re-visit the Hitec web site and/or the Hitec forum(s) here - IIRC Hitec has revised their recommendations for karbonite-geared servos and now specify an upper weight limit for the model, and further advise against using the karbonite servos in gas-engined models.

I _think_ I remember reading that in one or another forum, but don't recall which one.

RE: Servo noises?
 

Well I did some more investigation and found that the servo had three missing teeth. Two were on the gear that mesh's with the output shaft gear (small teeth), and one on the motor output shaft (large tooth). So the servo was jamming on the missing teeth and then all of a sudden jumping through that spot. Causing the clunk...

I wasn't aware that Hitec said not to use these karbonite servos on gasser and aircraft over 12lbs. So I guess I was lucky to find it when I did. I failure must of happened durring my last flight last weekend, as all was good before engine start and takeoff. So I guess I'll pull the other karbonite servo out of the other wing panel and replace them with MG servos!!

Thanks for your help!!