ive noticed when flying my plane it acts like its getting hit, i think maybe its the servos glitching . Its a tower trainer 40 with and os 40 and futaba t6xas radio and fp127 receiver . i also notice if the radio is off and the receiver is on and i pump the gas the servos go crazy but as soon as i switch the radio on it stops. My radio is PCM PPM selectable and i have it on PPM is that where it should be .

I typically get random servo movement whenever I do anything with electrical connections around my plane... e.g. plug in a glow ignitor connected to my starter battery, etc.

However this has never affected my plane in flight.

I have had servos that randomly move due to interference from the motor.

Typically these are bad servos though, and I end up replacing them, causing this to stop.

Perform a range check.

Then run up the engine with the plane restrained and have someone watch the servo movement as you get to about the same distance you were having problems.

Remember that local towers, etc. can cause interference that will NOT show up as an occupied channel.

G'day Mate,
It's normal for PPM RX's to glitch the servos, when the TX is off, that's why you should turn your TX on first, then the RX, & RX off first, then TX.
Do a range check.

where do you have your antenna? and are you using a metal clevis on the engine push rod?

Don't confuse glitches with normal flight with burbling air. If you have wind, the plane will apper to be glitching, or moving on it's own without input from you. It will hop up and down and may move left and right.. enough for you to see, and think it may be glitching.

What jetmech05 was referring to is that if you have a metal clevis attached to a metal control arm it MAY generate an RF interference signal intermittantly. Use a plastic/nylon clevis if the arm is metal.

yes always turn tx on first and off last,

thanks guys i have a plastic clevis on the engine , the intenna might be the problem i dont know its running over the top of the servos and out the top of the plane behind the wing and then connects to the tail . I dont think its wind ive been flying late in the evening when its calm and when it hits the plane is like trying to ride a bull for about 9 seconds , then it smooths out and will fly right . Its done this a few times when taking off and making a left turn and a few times when doing acrobatics . Should i switch my transmitter to pcm instead of ppm ?

a ppm reciever will not work with your tx in pcm mode you will need a pcm rx,move your antenna so it exits in front of the wing and goes to the tail.it is probably picking up rf noise from the srvos if you have it running across the top