My friend has a Zenoa 20cc with CDI unit in a CMPro Piper controlled by a Xtreme Link 2.4Ghz radio.
On first flight the plane did an involuntary roll (high enough to cut engine) and land safely.
On further ground testing, it was evident that involuntary servo movement took place on throttle up.
Metal to metal contact on throttle was replaced with nylon ball joint but problem persisted.
Also 2.4 Rx was placed at least 300mm from engine.
Last resort will be to replace a pull pull metal rudder servo arm with strong plastic arm.
Failing those remedies, what could be the cause???