Incident Narrative
Shortly after departing, smoke appeared in the cabin. The pilot initiated a turn to return to the runway. When the electrical master switch was turned off, the engine immediately lost power. The pilot attempted to restart the engine multiple times, but these efforts were unsuccessful. With no engine power, the pilot executed a forced landing away from the airport. During the landing, the aircraft struck a heavy cable.
Investigation Findings
A post-crash examination revealed a broken weld at the rear of the left muffler. Heat from the left muffler had melted the insulation on the "P" leads to the magnetos. This caused the leads to become grounded, which shorted the magnetos and resulted in the engine shutting down. The failure of the muffler weld and subsequent damage to the ignition leads was identified as the mechanical issue leading to the loss of engine power.
Sequence of Events
The incident sequence began with the appearance of smoke in the cabin shortly after departure. The pilot's reaction was to turn the aircraft around. The actuation of the electrical master switch coincided with the cessation of engine power. Despite best efforts, engine restart proved impossible. The forced landing, conducted off the airport property, ended with the aircraft contacting a substantial cable. The subsequent investigation uncovered a fractured weld on the left muffler's rear. The intense heat from the muffler had liquefied the insulation on the magneto "P" leads, creating an electrical short. This short effectively grounded the magnetos, resulting in the loss of engine power.