I'm flying a heli and a fixed wing plane from the same Tx with duplicate receivers. The plane flys OK, no problem, but the heli occasionally "jumps" just like a person would when getting a static jolt. I'm looking for suggestions on what the problem could be.

The setup is that I am using a 5-cell NiCd battery (unregulated).
The Rx antenna is routed well away from everything else.
All metal parts (except bearings) are bolted tight.
The receiver is well padded as is the battery pack.

I've tried tapping on various components (receiver, servo, battery, switch, gyro and mechanical assemblies) with no effect. The problem only seems to occur while flying, and the problem can happen at any distance from 10 to 200 feet. Since a heli is basically a flying Cuisinart, it makes me very nervous when this lapse of control occurs.

Am I overlooking something?