What happened
During an instructional flight consisting of practice autorotations and rapid decelerable maneuvers, a helicopter experienced a dynamic rollover. The flight was being conducted over a grassy and dirt area characterized by small mounds approximately 1.5 feet high. Due to recent thunderstorms, the ground surface was wet and muddy.
While performing the third quick-stop maneuver of the session, the student pilot attempted a normal takeoff from a three-foot hover. As the aircraft accelerated, it assumed a pronounced nose-low attitude. Simultaneously, the toe of the right landing gear skid struck a dirt mound. The student pilot attempted to correct the resulting right yaw by over-controlling to the left, while the flight instructor applied right cyclic and raised the collective. This sequence of events caused the aircraft to reach a critical angle, resulting in the helicopter rolling onto its left side.
Both the flight instructor and the student pilot were not injured and were able to exit the aircraft without assistance.
The investigation
The inspection of the aircraft revealed structural damage to the fuselage, tail boom, tail rotor, and main rotor. At the time of the accident, the flight instructor had 116 hours of flight instructor experience, while the student pilot had accumulated 24 total hours in helicopters.