NTSB Identification: FTW00LA068.
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Accident occurred Wednesday, January 19, 2000 in TYLER, TX
Probable Cause Approval Date: 03/02/2001
Aircraft: Mooney M20K, registration: N1157G
Injuries: 1 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.

The pilot reported that the engine lost total power while in cruise flight between 1,500 feet and 2,000 feet agl. He executed a forced landing, during which the airplane contacted a fence post. During the postaccident examination of the engine, the crankshaft drive gear was observed fractured. Three consecutive gear teeth of the crankshaft drive gear separated, of which two were recovered. The crankshaft drive gear and gear teeth were examined at the NTSB Materials Laboratory and three areas of fatigue were observed. Each fatigue area originated at the relief radius at the root of one of the three separated teeth. No tooling marks or gouge marks were observed near the fracture surface or on the remainder of the crankshaft gear's teeth. The outermost nitrided layer of the crankshaft drive gear appeared smooth and no cracks were noted. Additionally, machining marks through the entire crankshaft drive gear appeared consistent.

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

The failure of the crankshaft drive gear as a result of fatigue, which resulted in a forced landing. A factor was the lack of suitable terrain for the forced landing.

Full narrative available

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