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ASN Wikibase Occurrence # 134963
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Type:Silhouette image of generic EXEC model; specific model in this crash may look slightly different
RotorWay Exec 90
Registration: N52988
MSN: 1
Fatalities:Fatalities: 0 / Occupants: 2
Aircraft damage: Written off (damaged beyond repair)
Location:Kalamazoo, MI -   United States of America
Phase: En route
Departure airport:Kalamazoo, MI (4N0)
Destination airport:
Investigating agency: NTSB
The helicopter was destroyed by impact forces and a post crash fire while attempting an auto-rotation after a mechanical failure. The pilot stated that he was practicing takeoffs, hovering, and quick stops above the runway. After takeoff, at about 50 feet and 50mph, he lowered the collective to initiate a quick stop. At this point the engine RPM revved up out of control. He pulled up on the collective to re-engage the drive system, but the system would not engage. He entered into an auto-rotation, and as he neared the ground the helicopter began to slide sideways, folding the skids under the helicopter. The helicopter then rolled on its side, and the occupants climbed out prior to the post crash fire. Subsequent examination of the helicopter's drive system revealed that the drive shafts, pulleys, and drive belts were intact. The only device within the helicopter drive system that could not be determined to be in working condition was the sprag clutch which transmits engine power to the rotor drive system. The sprag clutch was not examined during the course of the investigation.
Probable Cause: The failure of the sprag clutch which resulted in the disengagement of the drive unit and the pilot's misjudged landing during the autorotation. A factor was the low altitude at which the failure occurred.




Revision history:

21-Dec-2016 19:26 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]
04-Dec-2017 18:35 ASN Update Bot Updated [Operator, Departure airport, Source, Narrative]

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