http://www.ntsb.gov/ntsb/brief.asp?ev_id=20001211X09614&key=1Accident occurred Tuesday, February 24, 1998 in FIFE, WA
Probable Cause Approval Date: 12/8/1998
Aircraft: Cessna 150F, registration: N8794G
Injuries: 2 Uninjured.
The Subaru Legacy powered Cessna 150 experienced a partial loss of engine power about 30 minutes after takeoff. Soon thereafter, the engine lost all power, and the pilot executed a forced landing in a nearby field. Although the touchdown was successful, the nose gear dug into the soft terrain as the pilot applied brakes to stop short of an upcoming ditch. After the nose gear dug into the terrain, the aircraft flipped over onto its back. A teardown of the engine revealed that the head had fractured off one of the exhaust valves in the forward left cylinder, resulting in the destruction of the piston.
The National Transportation Safety Board determines the probable cause(s) of this accident as follows:
The fracture separation of an exhaust valve head, followed by the total failure of the associated piston. A factor was the soft terrain at the location of the forced landing.