NTSB Identification: SEA98TA152.
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Accident occurred Wednesday, July 29, 1998 in BURNS, OR
Probable Cause Approval Date: 01/11/2000
Aircraft: Cessna TU206G, registration: N756YC
Injuries: 1 Minor,1 Uninjured.
NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this public aircraft accident report.
The pilot reported that during cruise flight, the engine suddenly lost power. He attempted a restart without success. During the forced landing to a road in a canyon, the airplane suddenly lost altitude and touched down hard in sage brush short of the road. During the landing roll, the airplane collided with a barbed wire fence which turned the aircraft perpendicular to the road. After the airplane was recovered, the engine was examined. During the examination, it was found that the crankshaft had failed. The crankshaft was 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.' The metallurgist reported that evidence of fretting was noted on the parting line faces between the connecting rod arm and cap. The joint between the two components could have been loose and may have created spinning of the bearing inserts.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: Fatigue failure of the crankshaft. Full narrative available
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