What happened
During a training session involving autorotation maneuvers, the flight instructor reported that he and his student were executing their fourth or fifth attempt at the procedure. As they approached the designated landing zone, it appeared the aircraft would overshoot the intended touchdown point. To correct the trajectory, the crew initiated a series of "S" turns to lose altitude while maintaining forward momentum. Following these maneuvers, the instructor began the flare sequence to arrest the descent rate.
However, instead of leveling out, the helicopter continued to descend with significant force. The aircraft impacted the ground on its rear skids, causing the tail boom to separate completely from the main fuselage.
The investigation
Post-accident examination revealed that the impact forces were sufficient to sever the tail boom at its attachment point. The structural failure was consistent with a hard landing following an uncontrolled descent during the final phase of the autorotation maneuver.