Accident Sequence
During cruise flight, the engine lost power unexpectedly. The pilot attempted to restart the engine but was unsuccessful. A forced landing was initiated toward a road situated in a canyon. During the approach, the airplane suddenly lost altitude and touched down hard in sage brush, stopping short of the road. As the airplane rolled after touchdown, it collided with a barbed wire fence, which turned the aircraft perpendicular to the road.
Post-Accident Examination
After the airplane was recovered, the engine was examined. The examination revealed that the crankshaft had failed. The crankshaft was subsequently inspected by a metallurgist, who reported that the crankshaft was broken through the crankcheek between the number two main bearing journal and the number two connecting rod journal. The metallurgist stated that the features over the major portion of the fracture were typical of fatigue cracking that initiated from the aft radius of the number 2 main bearing journal and propagated through more than 90 percent of the crankcheek before final separation. Additionally, evidence of fretting was noted on the parting line faces between the connecting rod arm and cap. According to the metallurgist, the joint between the two components could have been loose and may have created spinning of the bearing inserts.