Accident Details
A helicopter was engaged in practice touchdown autorotations when it landed hard on uneven terrain short of the intended touchdown point. The incident occurred during a training flight involving a commercial pilot-rated student and a flight instructor.
Flight Sequence
The student was demonstrating an autorotation with a turn to the runway. As the turn was completed and alignment with the runway began, the helicopter's rotor rpm decreased to 70 percent. Halfway through the maneuver, the flight instructor determined that the helicopter was too low and too slow to safely execute a power recovery and assumed control of the aircraft. Subsequently, the helicopter touched down short of the runway on rough terrain.
Postflight Inspection
A postflight inspection of the helicopter identified wrinkles in the tail boom, indicating structural stress from the hard landing.
Pilot Information
The pilot under instruction held a rotorcraft helicopter rating.