NTSB Identification: CHI00LA178.
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Accident occurred Friday, June 30, 2000 in TOLNA, ND
Probable Cause Approval Date: 08/21/2001
Aircraft: Weatherly 201C, registration: N9228W
Injuries: 1 Fatal.
NTSB investigators may have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
The airplane was destroyed by impact with terrain while maneuvering. The right wing was found detached and was found on the township road. A post crash fire occurred in the fuselage and left wing. The North Dakota Highway Patrol report stated, "The wing came off the plane and the plane then crashed approx. 396' west of the township road in a field of flax. The plane came to rest and was burning approx 471' west of the township road." The pilot sustained fatal injuries. The annual inspection was completed on May 1, 2000. The airplane had 343 hours since its last annual inspection and "5,400+" hours total time. Sections of the separated right wing and its mating surface were cut away and shipped to the NTSB's Materials Laboratory for detailed examination. Crack arrest lines and striations were found in the fracture area. Corrosion was observed on portions of the spar cap fracture surface. Circumferential grooves were observed. The upper and lower sides of the spar cap hole and adjacent fracture surfaces using scanning electron microscopy indicate fatigue origins initiating from corrosion pits on the hole surface. Subsequent to the accident the manufacturer issued a mandatory service bulletin to inspect the spar for cracks before the next flight and subsequent inspections accomplished at intervals no greater than 500 hours of flight.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: the wing spar fatigue and wing separation while maneuvering. A factor was that the fatigue was not detected by the mechanic during the last annual inspection. Full narrative available
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