NTSB Identification: DEN99LA108.
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Accident occurred Friday, June 25, 1999 in CREEDE, CO
Probable Cause Approval Date: 11/30/2000
Aircraft: Beech B90, registration: N221NC
Injuries: 7 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 flight instructor said the airplane felt like it was being pushed down onto the runway. As power was added, the airplane touched down 'approximately 90 KIAS (a loss of 10 to 15 knots indicating a shear)' and there was a loud 'bang.' The airplane became airborne momentarily, then touched down again. The airplane departed the right side of the runway on its nose and left main landing gear. The owner-pilot receiving instruction said 'the bottom fell out and a moderately hard landing was made on the main gear. A pilot who witnessed the accident landed hard moments before. He said he had encountered a 'vertical wind shear.' He saw a large puff of blue gray smoke come out from beneath the right wing, followed by the tumbling right main gear. Metallurgical examination of the right scissors torque link disclosed multiple fractures and a crack in the upper link. The fractures were 'typical of fatigue cracking,' originating from 'multiple sites.' There was also corrosion pitting. Two other fracture sites were 'indicative of overstress.'
The National Transportation Safety Board determines the probable cause(s) of this accident to be: Overload failure of the right main landing gear scissors torque link precipitated by preexisting fatigue fractures. A factor was wind shear. Full narrative available
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