What happened
The pilot was conducting flight training maneuvers involving power recovery autorotations. Following this practice, the pilot attempted a power-off, full-stop autorotation. During the approach phase of this maneuver, the main rotor RPM decayed significantly. The pilot did not take corrective action to maintain the required rotor speed.
The aircraft landed hard with slight forward motion. Upon impact, the pilot applied aft cyclic control input. This action caused the main rotor blades to strike the tail boom. The force of the impact caused the helicopter to roll over onto its right side.
The investigation
The physical evidence indicated that the main rotor had struck the tail boom during the post-landing sequence. The rollover occurred on the right side, consistent with the application of aft cyclic following a hard landing.