Incident Overview
The aircraft was in cruise flight at an altitude of approximately 500 feet above ground level (AGL) when the pilot reported hearing a distinct 'ping' sound emanating from the engine. Immediately following this sound, engine power decreased to flight idle.
Emergency Landing Attempt
The pilot initiated an autorotation, aiming for a cleared area that sloped upward. During the descent, the pilot had to increase collective pitch to avoid a fence. This action altered the landing profile, resulting in a hard touchdown. The hard landing caused the main rotor blades to strike the tailboom.
Investigation Results
An in-depth investigation of the engine was conducted to determine the cause of the spool-down. Despite thorough analysis, investigators were unable to identify a specific reason for the engine power loss. No other anomalies were noted in the aircraft's systems.