Accident Details
The pilot reported that shortly after leveling off at 11,500 feet mean sea level (MSL), the engine exploded. Both windscreens were covered with oil and fire as a result. During the emergency descent, the fire stopped. The aircraft landed without further incident on runway 30 at Bishop Airport in Bishop, California.
Investigation Findings
Disassembly examination of the engine revealed that the crankshaft had failed at the short cheek between the No. 3 main journal and the No. 4 crankpin. The No. 3 and No. 4 connecting rods, as well as the camshaft, were fractured. The pistons showed no evidence of detonation. Extensive fretting signatures were found on the backside of the connecting rods, main journal bearings, and both halves of the crankcase, indicating misalignment during manufacture.
Metallurgical Examination
Metallurgical examination determined that the crankshaft failed in fatigue. All other fractures were overload failures that occurred subsequent to the crankshaft failure. The engine had accumulated 602 flight hours since new.