NTSB Identification: CHI97IA075.
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Scheduled 14 CFR operation of MESABA AVIATION
Incident occurred Wednesday, January 22, 1997 in CHARLESTON, WV
Probable Cause Approval Date: 01/30/1998
Aircraft: de Havilland DHC-8-102, registration: N852MA
Injuries: 11 Uninjured.
NTSB investigators used data provided by various sources and may not have traveled in support of this investigation to prepare this aircraft incident report.
The captain said that during takeoff rotation, the airplane rolled left. He noted no warning lights or horns before or during the event. He applied right control wheel and right rudder to stop the left roll. After the captain had the airplane's roll stabilized, he 'made a wide left pattern and returned to the departure airport.' The airplane was landed without further incident. A postincident inspection of the airplane revealed that the left inboard roll spoiler was 'jammed and partially deployed.' An examination and disassembly of the roll spoiler servoactuator revealed that a plug (PN A50993-1), which had been fusion-welded into the base of the piston (PN A50992-1), had separated and lodged between the base of the piston and the shims, restricting the piston's movement. Dowty Aerospace (the manufacturer) had recorded six previous failures of fusion welds in pistons on DHC-8 roll spoiler servoactuators before this incident.
The National Transportation Safety Board determines the probable cause(s) of this incident to be: a fractured fusion weld in the piston of the roll spoiler servoactuator, which allowed the plug at the base of the piston to separate and jam the piston. A factor relating to the incident was: the inadequate design of the airplane's roll spoiler servoactuator piston. Full narrative available
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