NTSB Identification: LAX01LA232.
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Accident occurred Monday, July 02, 2001 in Hayward, CA
Probable Cause Approval Date: 05/30/2003
Aircraft: Robinson R22 Beta, registration: N4052K
Injuries: 2 Minor.
NTSB investigators may have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
The helicopter impacted the ground, bounced, and impacted the ground a second time during a practice autorotation. The commercial/student pilot was practicing a 180-degree autorotation with a power recovery when an excessive rate of descent developed. The flight instructor said he "joined" the student on the controls and initiated a progressive rollout of the turn while simultaneously applying aft cyclic, raising the collective, and applying more power for a power recovery to level flight. The instructor said that the engine did not respond to the throttle input. Due to the rate of descent, the flight instructor elected not to attempt an "aggressive" flare "fearing a tail rotor ground strike." He continued with aft cyclic input and collective manipulation to reduce forward airspeed and rate of descent for a run-on landing. The helicopter contacted the ground in a "near skids level attitude" approximately 30 knots, with the rotor rpm in the "high end of the green region." The helicopter became airborne approximately 8-10 feet above the ground. The flight instructor indicated that the throttle was still unresponsive. He raised the collective to cushion the second impact and the low rotor rpm warning light and horn came on prior to set down. The helicopter impacted the ground again approximately 20 knots, collapsing the left skid. The helicopter then rolled to the left and came to rest on its left side facing approximately 180 degrees from the approach heading. A post-accident examination of the helicopter revealed no anomalies, with the exception of a failed left seat restraining system. An engine test run was conducted and no anomalies were noted that would have affected its operation.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: the student's excessive rate of descent during a practice autorotation, and, the inadequate use of the rotorcraft flight controls by both pilots during the attempted recovery, which resulted in a hard landing. The flight instructor's inadequate supervision during the maneuver was also causal. Full narrative available
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