Accident Overview
A turbine-powered single-engine helicopter experienced a loss of engine power during cruise flight. The pilot, who had accumulated 21,440 total flight hours, initiated an autorotation and landed the helicopter on water. Examination of the airframe and engine revealed no anomalies. Approximately 47 gallons of fluid were drained from the main fuel cell. Of that fluid, about one quart was consistent with fuel, indicating the remainder was likely not fuel.
Pilot and Maintenance
The accident pilot had recently come on duty, and this was his first flight in the accident aircraft. He reported to an inspector that he did not observe any discrepancies related to the airworthiness of the helicopter. However, before the accident flight, the pilot who flew the helicopter on the previous flight informed company maintenance personnel that the fuel quantity gauge indicated a higher fuel level than actual and was inaccurate. Review of company records showed that maintenance personnel had placed an order for a new fuel quantity gauge for the accident aircraft the day before the accident. Examination of the helicopter's maintenance records revealed no entries regarding the inaccurate fuel quantity gauge. Additionally, there were no placards indicating that the fuel quantity gauge was inoperative.
Examination Findings
A detailed examination of the helicopter uncovered no mechanical issues with the airframe or engine. The significant finding was the composition of the fluid drained from the main fuel cell: of the 47 gallons drained, only about one quart was consistent with fuel. This suggests the fuel cell contained mostly non-fuel fluid, though the source does not identify that fluid.