Accident Overview
During a training flight focused on 180-degree autorotations, the helicopter experienced an unexpected increase in descent rate at an altitude of approximately 150 feet above ground level (AGL). The flight instructor reported that the descent rate increased dramatically at that point.
Flight Details
The instructor attempted to recover from the high descent rate by applying aft cyclic and lowering the collective. Subsequently, full throttle was added and the collective was raised in an effort to achieve a skid-level landing attitude. Despite these actions, the helicopter struck the ground with significant force.
Impact and Aftermath
The impact collapsed both skids of the helicopter. The main rotor blade then struck and severed the tail boom. Following the impact, the helicopter rotated three to four times before coming to rest off the left side of the runway.
Post-Accident Examination
A detailed examination of the helicopter's systems was conducted. No anomalies were found in any of the systems, indicating that the accident was not caused by a mechanical failure.