NTSB Identification: ATL05LA051.
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Accident occurred Friday, February 18, 2005 in Smith, AL
Probable Cause Approval Date: 12/20/2005
Aircraft: Mooney 20P, registration: N321DT
Injuries: 1 Serious.

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 on an instrument flight the engine stopped and oil covered the windshield. The pilot declared an emergency and the air traffic controller attempted unsuccessfully to vector the flight to a nearby grass airstrip. The pilot selected an off-airport location for an emergency landing. The airplane collided with a tree while the pilot was maneuvering for the emergency landing. Post-accident examination of the engine revealed that the #2 cylinder assembly had separated from the crankcase. The #2 cylinder was recovered and exhibited fretting on the mating surface of the base flange. Post-accident examination revealed that the torque on the adjacent cylinder hold down nuts were less than what was prescribed for installation. A review of the engine maintenance records revealed that on 12/18/2002, the #1 cylinder assembly was replaced. The cylinder was overhauled by Aviation Engines and installed by North Alabama Aviation. At the time of the accident the engine had accumulated 85.6 hours since the #1 cylinder assembly had been replaced.

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

Maintenance personnel failure to properly torque the cylinder head during installation that resulted in the separation from the engine assembly and the subsequent loss of power.

Full narrative available

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