What happened
During an air tour flight at an air show, the pilot of a turbine powered helicopter prepared for departure by refueling the aircraft. The facility being used for refueling only had 100LL aviation gasoline available, whereas the aircraft normally utilizes Jet 'A' fuel. Consequently, the pilot added 15 gallons of 100LL to the existing fuel load, which contained less than 10 gallons of Jet 'A'.
Approximately twenty-two minutes into the flight, while en route to a facility where Jet 'A' was available, the helicopter experienced a partial power loss. In response to the power loss, the pilot performed an autorotation. The maneuver concluded in a hard landing.
Findings
The investigation determined that while the aircraft's operating manual permits the mixing of Jet 'A' and aviation gasoline, such a mixture requires the use of the fuel boost pump during operation. In this instance, the pilot did not have the fuel boost pump turned on.