Primary finding
Probable cause
The student pilot's loss of lateral control while practicing autorotations from a hover and the flight instructor's delayed remedial action, which resulted in a bounced landing and dynamic roll-over.
Investigator assessment
Analysis narrative
The flight instructor in the helicopter reported that the student pilot was practicing autorotations from a hover while pointing the helicopter into the wind over tall grass from about 1 ft above the ground. He added that the student "rolled off the throttle, the helicopter descended to the ground, appeared to bounce, moved slightly to the right and began a quick roll to the right." Subsequently, the helicopter pivoted on its right skid, the main rotor impacted terrain, and the helicopter rolled over to the right. The main rotor and windscreen sustained substantial damage. The flight instructor reported that there were no preaccident mechanical malfunctions or failures with the helicopter that would have precluded normal operation.
Source record
Factual narrative
The flight instructor in the helicopter reported that the student pilot was practicing auto-rotations from a hover, while pointing the helicopter into the wind over tall grass, from about 1 foot above ground. He added that the student, "rolled off the throttle, the helicopter descended to the ground, appeared to bounce, moved slightly to the right and began a quick roll to the right." Subsequently, the helicopter pivoted on it's right skid, the main rotor impacted terrain, and the helicopter rolled over to the right. The main rotor and windscreen sustained substantial damage. The flight instructor reported that there were no preaccident mechanical malfunctions or failures with the helicopter that would have precluded normal operation.