Event Details
A helicopter executing a practice 180-degree full touchdown autorotation experienced a hard landing. The landing gear skids spread, and the main rotor blades flexed and chopped off the tailboom. The helicopter bounced into the air, landed again, and spun several times before coming to a stop.
Sequence of Events
The student initiated the maneuver at 500 feet above ground level. He started the turn abeam the runway, and at 90 degrees into the turn, the airspeed was 65 knots and rotor rpm was 105 percent. The student increased collective to prevent the main rotor from overspeeding as he continued the turn. The pilot leveled off and aligned the helicopter with the runway for landing. The flight instructor instructed him to lower the collective, which the student did, and also applied aft cyclic to start the flare. The instructor took over flight controls when it became evident that the student could not arrest the descent. The instructor ensured the helicopter was leveled and attempted to cushion the landing prior to ground contact.
Pilot Statements
Both pilots reported that there were no mechanical anomalies. The instructor indicated that the combination of a higher descent rate, higher airspeed, and density altitude led to the accident.
Environmental Conditions
The airport was at an altitude of 2,671 feet mean sea level. The calculated density altitude was 4,200 feet.