NTSB Identification: SEA04LA189.
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Accident occurred Monday, September 13, 2004 in Clearwater, ID
Probable Cause Approval Date: 07/07/2005
Aircraft: Cessna P206A, registration: N4661F
Injuries: 4 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.

While en route, the aircraft's engine began to run rough, vibrate, and make a lot of unusual noises. Soon thereafter the oil pressure dropped to 0 psi, and the engine seized. The pilot then attempted an emergency power-off landing in an open field, but the nose gear collapsed, and the nose gear strut dug into the dirt resulting in the aircraft nosing over onto its back. A teardown inspection of the engine revealed that the number three piston pin had failed, and as a result a significant portion of the internal components of the engine had been destroyed. An examination of the Superior Air Parts piston pin revealed that it had failed along a fatigue crack that propagated across the longitudinal axis of the pin. The portion of the pin that contained the origin of the crack was not recovered, and therefore a determination of the initiating factor could not be made.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

A loss of engine power due to fatigue crack propagation of the number three piston pin while in cruise flight, leading to a power off forced landing in an open field. Factors include soft uphill terrain.

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