Accident Sequence
During cruise flight, the helicopter experienced a partial loss of engine power. The pilot executed an autorotation to a rocky shoreline. After a successful landing, the helicopter slid aft on slippery rocks, causing the tail rotor blades to impact the ground.
Fuel Contamination
Post-accident examination revealed that the fuel system had been contaminated. Two days before the accident, a fuel sample from the helicopter was found contaminated, but the entire fuel system—specifically the fuel tank—was not examined or cleaned. Following the accident, the fuel tank cells were examined, and contamination was noted in the tank, the fuel pump inlet screen, and the outlet.
According to the manufacturer, the corrective action for fuel contamination is to "inspect and clean the fuel cell and start pump inlet screens if large amounts of foreign material are found in the engine driven fuel pump filter (or the optional airframe fuel filter if installed)." The accident helicopter was not equipped with the optional airframe fuel filter.
Fueling Practices
The contaminated fuel was introduced to the system two days prior. The fuel originated from a remotely located fuel tank that had a broken cover, which allowed water and contaminants to enter. The individual who fueled the helicopter from that tank was not trained in the company's policy to conduct a daily quality assurance check and had not sumped the tank, filters, or hoses.