Hello all,
New here and new to RC flying, just soloed on my trainer yesterday. I'm having trouble with another plane. It has an older airtronics radio that has a glich once or twice during almost every flight. It seems that it is the rudder jumping around for just a split second. What could be causing this? I bought all my stuff from a guy that has not been flying for several years. I took the receiver out of my trainer that has always flown trouble free and put it in the other plane. Hope to try it out today and see if it still has the glitch. If it still does it, what else could be the problem? Could the servo have a problem and move on it's own?
Thanks.

WOW,
thats a tuff one to diagnose verbally. Definatly do not fly it until this is resolved (major safety issue).

There is a list of possible causes. Best take it to your field and have a couple of experienced fliers check it out.

If you do this hobby very long a problem such as this bites just about everyone sooner or later, HANG IN THERE

Yes, it could be the servo. Could have a dirty pot or other problem. If it's JUST on the rudder and a VERY brief glitch it might be worth ONE flight test. First glitch, LAND and replace the servo. Replace the servo BEFORE flying if you have one available as they are not that expensive compared to a plane and safety issues.

Does the glitch seem to be range sensitive at all?

ok, first plug the batery pack straight in to the rx without the switch(old switches can develop dirty contacts in storage)then check operation.If there is still a problem plug the trottle servo into the rudder connection of the reciever and the rudder servo into the throttle connection of the reciever,if the problem travels with the servo to the throtle channel replace it,could be a bad gear or a dirty wiper on the feedback pot.also check for any metal to metal contact especially at the carb . post your findings.

Well I switched receivers in my planes. Took the one out of the Super Sportster and put it in my LT-40 and put the LT-40 receiver in the Sportster that was having the problem. I flew the LT-40 first. Went through 3 tanks of fuel without a hitch, no sign of the glitch. So I figured no guts, no glory and put the Sportster in the air. Flew 4 tanks of fuel through it without one single hiccup. So now I don't have any idea, except that it may have been outside interference from some other source. There was only one other pilot at the field tonight and he was on a Spectrum. The other times I experience the glitch the field was pretty busy, but no one else has a radio on my channel, that I know of. The only other thought was that there could have been a poor connection at the reciever that was fixed with the swap. I guess I'll keep things like they are for now.

No way to know for sure, but it sounds like that was the culprit. Swap RX's again to test is the only way to find out for sure. But if it was me, I'd leave well enough alnoe. Glad it's working for ya.