NTSB Factual Report

The flight instructor in the helicopter reported that he was providing hovering autorotation training to a private pilot. The flight instructor reported that he rolled off the throttle to initiate the maneuver and the private pilot, "raised the collective too soon which resulted in the aircraft climbing." The rotor inertia decayed and a main rotor blade struck the tailboom after the helicopter struck the ground. The helicopter sustained substantial damage to the tail rotor drive shaft.

The pilot reported that there were no preaccident mechanical malfunctions or failures with the helicopter that would have precluded normal operation.

NTSB Probable Cause

The pilot’s early increased application of the collective during a simulated hovering autorotation, which resulted in a loss of rotor rpm and subsequent main rotor blade strike of the tailboom.