What happened
While climbing through approximately 2,500 feet following takeoff, the engine suffered a complete loss of power. Due to the loss of propulsion, the pilot was forced to land on unsuitable terrain, which resulted in a collision with a tree. The pilot was not injured.
The investigation
Post-accident examination of the engine revealed that the left magneto had jammed because of a failed impulse coupling. This mechanical failure caused the jammed magneto to break both the idler gear and the crankshaft gear with which it meshed, which ultimately triggered the total loss of power.
Maintenance records indicated that the impulse coupling was subject to an airworthiness directive requiring inspections every 500 hours of engine operation. The most recent inspection of the magneto occurred in November 1988, at 432 hours following the engine overhaul. The last annual inspection was completed in October 1995, when the tachometer recorded 2,905 hours since overhaul. At the time of the accident, the engine had a total of 3,109 hours recorded since its overhaul.