I spent almost 2 weeks changing everything there is to change in a ez* to try to stop my motor cutting out and loosing all control of the plane. I had many suggestion from the forum to solve the problem but only 1 person suggested outside electric interference.

at the end of 1 flight the ever present onboard video was still running for a while as I was walking to collect it, on playback all was silent except for the sound coming from somewhere inside the ez* of and electric fence ticking away and the servos trying to activate.

checking over the hedge I found an electric fence keeping the cattle in, next day went to another field away from fences, all performed perfectly.........all this after fitting a new motor........new esc.........new rx.....new xtals.....changing the tx, plus a large repair on the fuse when all control was lost at 50ft at the time being flown by an expert flyer

be warned check for electric fences..............aparrently overhead power lines have no effect as it's a continuous current with cattle fences it's a pulse

Oh yeah. Spark transmitter! The first radio! But it seems the sparks would be far enough apart to just be a series of hits. Sorry for all your trouble, but very interesting. I wasn't flying back when I had electric fences. It is fun to touch the wire between pulses and then let your friends try it!
Glad you found the trouble though.