Accident Details
A private certificated helicopter pilot was conducting autorotation practice at a grass/turf-covered runway during a personal flight under 14 CFR Part 91. The pilot had previously performed two or three autorotations terminated with a power recovery to a hover.
Pilot Report
The pilot then decided to execute a touch-down autorotation. He reported to the National Transportation Safety Board investigator-in-charge that during the termination of the maneuver, he pulled excessive collective pitch and accelerated too much while leveling the helicopter at the conclusion of the deceleration flare.
Damage
As a result, the helicopter touched down hard and tilted forward onto its nose. The forward portion of the right skid tube fractured, and the main rotor blades struck the ground and the tailboom.
Conclusion
The pilot's actions during the touch-down autorotation led to the hard landing and subsequent damage. No other factors were reported.