Incident Description
The pilot of the helicopter was performing an autorotation during a maintenance flight to conduct a functional check of the free-wheeling unit. The helicopter was observed at an altitude of 100 to 150 feet above ground level.
Witness Observations
A witness reported that the main rotor blades "stopped" and the aircraft began a slow spiral to the left, nose down. The helicopter was shaking violently, and its skids were flexing in and out.
Postcrash Examination
Examination after the crash revealed that the fuel control pointer on the fuel control was positioned slightly above flight idle. Both cockpit throttles were also observed in a position slightly above flight idle.
Flight Data
The helicopter's power analyzer and recorder documented that at the time of impact, the engine's torque was at 13.5% and the main rotor speed was at 65.8%.
Recovery Procedure
The procedure for a power recovery from an autorotation is to smoothly roll the throttle back on, confirm that the rotor and N2 needles are joined and in the normal operating range, and simultaneously pull up on the collective while applying left pedal.