NTSB Identification: ANC96LA017.
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Accident occurred Saturday, November 18, 1995 in ANIAK, AK
Probable Cause Approval Date: 11/11/1996
Aircraft: Cessna 207, registration: N70076
Injuries: 2 Uninjured.
NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
During cruise flight, the pilot noted a loss in engine RPM and oil pressure at the same time. He performed an emergency landing on a frozen lake. During the landing roll, the right wingtip struck a spruce tree, and the airplane was substantially damaged. During an examination, the accessory section of the engine did not rotate, when the propeller was turned by hand. A teardown of the engine revealed that the crankshaft was fractured at the number 3 short cheek, between the number 2 rod bearing and the number 2 main bearing. The engine contained numerous fragments from the number 2 main bearing. The number 2 bearing saddle was severely worn and deformed. Other bearing saddles exhibited scoring. A metallurgical examination of the crankshaft revealed a fatigue failure at the aft radius of the number 2 main bearing journal adjacent to heavy rubbing marks from the number 2 main bearing.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: fatigue failure of the engine crankshaft at the number 2 main bearing journal, where rubbing contact had occurred with the number 2 main bearing. A factor relating to the accident was: the lack of suitable terrain for an emergency landing. Full narrative available
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