Many moons ago I was towing a glider with a Supermunk when a Godawful banging started, ditched glider at safe height & set up for low power RTB; no change with RPM or airspeed & stopped on landing. Transpired the earth lead had come adrift from the tail strobe & the noise was the strobe arcing to the airframe & echoing up the (old) loudhailer style rear fuselage.
