Accident Details
A helicopter experienced a hard landing during a practice autorotation, resulting in a rollover. The aircraft came to rest on its right side after the main rotor struck the tail boom. No mechanical malfunctions were reported.
Sequence of Events
During the training exercise, the certified flight instructor (CFI) initiated a throttle chop. The student pilot turned the helicopter into the wind, causing airspeed to decrease. In an attempt to regain airspeed, the student lowered the nose, but rotor rpm began to decay. The CFI stated "I've got it" twice, but the student did not release the controls. The CFI attempted a recovery maneuver but was unable to restore rotor rpm. When the helicopter was approximately 30 feet above ground level, the student relinquished controls. Just prior to impact, the helicopter shuddered. It impacted on the forward portion of the skids, causing the main rotor to strike the tail boom and the aircraft to roll onto its right side. The student did not relinquish control until the CFI stated "I've got it" for a third time.
Findings
No mechanical malfunctions were noted with the helicopter.