What happened
A local flight departed at 2320 on a very dark night. At the time of the accident, the outside air temperature was 16 degrees Fahrenheit. During the flight, the pilot reported that the engine stopped producing power, leading to an impact with the terrain. While performing an autorotation, the pilot observed that the rotor RPM had fallen below the red line.
The investigation
The investigation examined the aircraft's fuel shutoff valve and heating equipment. An aircraft heater had been placed inside the aircraft the previous day, though the pilot stated he did not use the heater for this flight. On the center console, both the heater and the fuel shutoff are activated by pulling their respective controls.
Although the pilot stated that he did not close the fuel shutoff valve prior to or following the collision, the fuel shutoff valve was found in the closed (pulled out) position after the accident. Rescue and fire personnel confirmed they did not close the valve following the impact. A subsequent test run of the engine showed that it operated within normal operating limits.