NTSB Identification: ANC13LA029
Nonscheduled 14 CFR Part 135: Air Taxi & Commuter
Accident occurred Wednesday, March 06, 2013 in Bethel, AK
Probable Cause Approval Date: 06/11/2014
Aircraft: CESSNA 207, registration: N1704U
Injuries: 3 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.
Shortly after departure on the commercial passenger/cargo flight, the airplane’s engine lost power. The pilot conducted a forced landing on a snow-covered, sparsely treed, tundra area. Just before touchdown, the left stabilizer struck treetops, and the airplane sustained substantial damage. A preliminary examination of the engine revealed a crack in the crankcase. A subsequent examination of the No. 1 piston assembly revealed fatigue fractures in both connecting rod retaining bolts. Additional internal engine damage was found to be consistent with damage caused by the release of the connecting rod from the crankshaft.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The failure of the engine’s No. 1 piston connecting rod retaining bolts due to fatigue fracturing, which resulted in a loss of engine power during cruise flight. Full narrative available
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