Accident Sequence
During the initial climb after takeoff, as the aircraft passed through approximately 2,500 feet, the engine experienced a complete loss of power. The pilot was forced to land on unsuitable terrain. During the landing, the aircraft collided with a tree.
Examination Findings
Post-accident inspection of the engine revealed that the left magneto was jammed. The jam was attributed to a failure of its impulse coupling. The jammed magneto subsequently broke the idler gear and the crankshaft gear it meshed with, resulting in the total loss of engine power.
Maintenance History
The impulse coupling was subject to an airworthiness directive requiring recurring inspections at every 500 hours of engine operation. Records indicated that the last magneto inspection was performed in November 1988, approximately 432 hours after the engine had been overhauled. The last annual inspection of the aircraft was conducted in October 1995, at which time the engine had accrued 2,905 hours since overhaul. At the time of the accident, the engine had accumulated a total of 3,109 hours since overhaul.