Accident Pitts S-1S N515TN, Friday 15 July 1994

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Date:	Friday 15 July 1994
Time:	15:45 LT
Type:	Pitts S-1S
Owner/operator:	Teresa & John Nagy
Registration:	N515TN
MSN:	7-0255
Total airframe hrs:	144 hours
Engine model:	Lycoming O-360-A4G
Fatalities:	Fatalities: 0 / Occupants: 1
Other fatalities:	0
Aircraft damage:	Substantial
Category:	Accident
Location:	Stevensville, MD - United States of America
Phase:	En route
Nature:	Private
Departure airport:	(3W3)
Destination airport:	Easton, MD (KESN)
Investigating agency:	NTSB
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
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.

Probable Cause: 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.

Accident investigation: