What happened
The rated helicopter pilot was conducting recurrent flight training at a designated training field under the supervision of a certified instructor. The specific maneuver being practiced was an autorotation to a landing, a critical emergency procedure used when engine power is lost.
During the execution of this maneuver, the aircraft entered a descent with an excessive vertical speed, commonly referred to as a high sink rate. Simultaneously, the main rotor system experienced a significant reduction in rotational speed, dropping below safe operational limits. This combination of factors prevented the pilot from arresting the descent effectively before ground contact.
The helicopter impacted the surface with considerable force while maintaining a tail-low attitude, meaning the rear of the aircraft was lower than the nose at the moment of touchdown. The impact resulted in structural damage to the landing gear and airframe.
The investigation
Post-accident examination of the aircraft revealed specific points of failure consistent with the described impact dynamics:
- The rear sections of the helicopter skids sustained visible damage from the hard contact.
- The tail boom, which supports the vertical stabilizer and tail rotor assembly, completely separated from the main fuselage structure.
No further mechanical anomalies were cited in the source documentation regarding the cause of the high sink rate or low rotor RPM during the maneuver.