Incident Overview
While in cruise flight, the airplane experienced a total loss of power from its left engine. The engine failure caused damage that prevented the propeller from being feathered, rendering the airplane unable to sustain flight. The pilot executed an emergency landing in a field. During the landing roll, the left main landing gear and nose gear collapsed.
Post-Accident Examination
A post-accident examination of the failed engine revealed that the number four cylinder and its piston were missing from the engine case. The left engine case and associated fasteners were sent to the National Transportation Safety Board's Materials Laboratory for detailed analysis. The laboratory examination identified fatigue cracking in the engine case, through bolts, and studs. Additionally, three of the six studs around the number four cylinder were not recovered.
Determination
The investigation was unable to determine the initial failure that led to the loss of the number four cylinder and the subsequent cascading damage. The source does not state a probable cause.