What happened
The aircraft was cruising at approximately 5,500 feet when the engine suddenly lost power. Although the propeller continued to windmill, the pilot was unable to restart the engine. The pilot subsequently landed the aircraft in a rough field. During the landing roll, the propeller dug into a mound of dirt, which caused the aircraft to flip over.
The investigation
An examination of the engine revealed that a bolt had not been properly installed to secure a crankshaft gear during an overhaul performed in 1984. This mechanical failure was identified as the primary reason for the loss of power.
Findings
The investigation determined that the improper installation of a bolt during the previous overhaul contributed significantly to the accident. The lack of proper securing allowed the crankshaft gear to fail, leading to the engine stopping while in flight.