NTSB Identification: NYC94LA129.
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Accident occurred Friday, July 15, 1994 in STEVENSVILLE, MD
Probable Cause Approval Date: 03/27/1995
Aircraft: PITTS S-1S, registration: N515TN
Injuries: 1 Minor.

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 AIRPLANE'S ENGINE LOST TOTAL POWER JUST AFTER TAKEOFF WHEN THE PILOT REDUCED THE THROTTLE. THE PILOT RE-APPLIED FULL THROTTLE WITH NO RESULT. DURING THE FORCED LANDING IN A FIELD, THE AIRPLANE'S WING STRUCK A TREE, AND THE AIRPLANE NOSED OVER. EXAMINATION OF THE ENGINE REVEALED THAT THE CRANKSHAFT GEAR (13S19646) BECAME DISCONNECTED FROM THE CRANKSHAFT DUE TO A BROKEN BOLT. METALLURGICAL EXAMINATION OF THE ACCESSORY GEAR RETAINING BOLT (P/N STD-2213), AND DOWEL PIN (P/N STD-1065) REVEALED THAT THEY SEPARATED AS A RESULT OF HIGH CYCLE FATIGUE MECHANISM, MOST LIKELY CAUSED BY INSUFFICIENT TORQUE OF THE BOLT.

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

Inadequate maintenance by which undertorquing of the accessory gear retaining bolt resulted in fatigue failure of the bolt and the subsequent loss of engine power.

Full narrative available

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