NTSB Identification: LAX02LA096.
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Accident occurred Monday, February 25, 2002 in Phoenix, AZ
Probable Cause Approval Date: 09/29/2004
Aircraft: Rotorway Rotorway Exec 90, registration: N9876D
Injuries: 2 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 experimental helicopter made a hard landing following a practice autorotation and loss of engine power. During the third practice autorotation, the student informed the instructor that he was unable to reintroduce power during the autorotation recovery. The instructor took control of the helicopter and attempted to roll the throttle up; however, he found it would not rotate any further. The instructor raised the collective at 10 feet agl in an attempt to cushion the landing. The helicopter hit the ground hard, the left skid collapsed, and the helicopter rolled onto its left side. Examination of the helicopter revealed the mechanical stop for the throttle was bent causing a condition in which the engine would stay at ground idle once the throttle was rolled past over center near the ground idle position. Once the linkage was driven over center, the linkage could not be moved by the throttle control A post accident run of the engine revealed no additional anomalies.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The student's inadvertent over control of the throttle mechanism, which resulted in the bending of the throttle mechanical stop and binding the linkage in the idle position. Also causal was the CFI's inadequate supervision. A factor in the accident was the CFI's inability to add engine power due to the bent throttle mechanism during a practice autorotation. Full narrative available
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