What happened
During a pinnacle departure attempt, the pilot maneuvered the helicopter into a hover approximately 3 feet above ground level. After verifying that all cockpit gauges showed appropriate indications, the pilot attempted to depart the area by trading altitude for airspeed while executing a right turn toward a planned escape route over downsloping terrain.
During this maneuver, the rotor RPM decreased. The pilot responded by applying full power via the throttle control and simultaneously lowering the collective. However, the rotor RPM failed to increase, causing the aircraft to continue its descent. In an attempt to cushion the impact with the ground, the pilot raised the collective just before the skids contacted the terrain. The aircraft subsequently rolled downhill and came to rest on its left side.
The investigation
The engine manufacturer conducted a test run of the engine following the accident. The testing revealed no discrepancies or anomalies that would suggest the engine was incapable of operating or producing the necessary power prior to the event.