What happened
The incident occurred during a flight training session involving an instructor and a student pilot in a helicopter. The instructor was conducting a maneuver that involved entering a steady-state autorotation from an altitude of 600 feet. The deceleration phase of the entry proceeded normally.
Upon termination of the autorotation maneuver, the instructor reported feeling a slight vibration. Shortly thereafter, he observed a piece of metal flying over and to the front of the helicopter. In response to this observation, the instructor immediately closed the throttle and shut down the engine. After exiting the aircraft, he inspected the exterior and confirmed that the tail section had sustained damage.
The investigation
The available source material does not provide details regarding a mechanical inspection or examination of the aircraft components beyond the visual confirmation of tail section damage by the instructor after shutdown.