Accident North American Navion D N10JF, Sunday 20 October 1991

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Date:	Sunday 20 October 1991
Time:	16:00 LT
Type:	North American Navion D
Owner/operator:	Private
Registration:	N10JF
MSN:	NAV-4-1391
Total airframe hrs:	5200 hours
Engine model:	Continental I0-520B
Fatalities:	Fatalities: 0 / Occupants: 4
Other fatalities:	0
Aircraft damage:	Substantial
Category:	Accident
Location:	Lake Geneva, WI - United States of America
Phase:	En route
Nature:	Private
Departure airport:	Delavan, WI (C59)
Destination airport:	Kenosha, WI (KENW)
Investigating agency:	NTSB
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
THE PILOT CLIMBED TO CRUISE ALTITUDE AND HAD SET POWER BEFORE THE ENGINE VIBRATED BRIEFLY AND QUIT. THE PILOT EXECUTED A FORCED LANDING IN A ROUGH FIELD. ENGINE TEARDOWN REVEALED A BROKEN CRANKSHAFT. THE FRACTURE SURFACE SHOWED FATIGUE EMANATING FROM A SCRATCH IN A FILLET AT THE NUMBER 2 MAIN BEARING JOURNAL.

Probable Cause: FATIGUE FAILURE OF THE CRANKSHAFT. A FACTOR IN THE ACCIDENT WAS INADEQUATE QUALITY CONTROL BY OTHER MAINTENANCE PERSONNEL.

Accident investigation: