Sequence of Events
While en route at 1,000 feet above ground level (AGL), the instructor pilot simulated an engine failure over a field and directed the student to execute an autorotation with a power recovery. The student pilot performed a gradual 360-degree turn while descending toward the field. According to the instructor, the student leveled the helicopter on final approach.
The instructor conducted a final scan for obstacles and then looked back into the cockpit. At that moment, the airspeed was 45 knots and the main rotor RPM was at the bottom of the green arc (approximately 97%). The helicopter was about 100 feet AGL when the instructor took over control and attempted a "high power recovery."
Instructor's Actions
The instructor rolled on the throttle and pulled up on the collective. He felt a "slight hesitation," after which the helicopter "snapped to the right." The instructor then applied left pedal and heard the low rotor RPM warning horn. The instructor stated that he believed the helicopter did not touch down level due to the rotation to the right.
The helicopter touched down in the field, then "hopped to the right approximately 40 degrees" and became airborne again. The instructor stated that he thought he still had full throttle applied and/or the collective raised. As the helicopter became airborne, it rotated 360 degrees to the right, contacted the ground with the tail rotor, and then with the right skid. Subsequently, the helicopter rolled over onto its right side.