Temsco Helicopters Aerospatiale AS-350B2 accident

The commercial certificated helicopter pilot, with 4 passengers aboard a single-engine, emergency float-equipped helicopter, was returning to its base after departing a remote glacier during an air tour flight. The helicopter was flying along the edge of a fjord, adjacent to steep terrain. About 2,200 feet msl, the engine lost power, and the pilot entered an autorotation. The pilot selected an emergency landing area at the rocky edge of the fjord. During the autorotation, the pilot pulled the manual activation handle to deploy the emergency floats, but they did not deploy. The pilot did not use the electrical emergency float deployment switch. Postaccident examination of the helicopter's emergency float system disclosed that the manual activation cable was improperly rigged. The pilot landed the helicopter in the water, on a rocky shelf. The pilot and passengers exited the helicopter into waist-deep water and gathered on the rocks. The helicopter remained upright for a short time, but then sank. The pilot reported that the helicopter was fueled before his departure, and the fuel quantity was 50 to 55 percent at takeoff. When the pilot departed the glacier on the accident flight, he said the fuel quantity was 30 to 35 percent. The flight from the glacier to the operator's base should have taken about 20 minutes. The pilot reported that the operator records a total daily use of fuel for its fleet of helicopters, but does not maintain individual fuel records for each helicopter. After the helicopter's recovery, an examination revealed that the fuel tank contained about 32 percent fluid. The fluid was sea water, except for about 1.5 quarts of fuel. Fuel was found in the airframe fuel filter, and in the fuel line from the filter to the engine fuel control. The fuel tank has an internal, resistor type fuel probe which incorporates a float, and a low fuel level position, which when reached, should illuminate a low fuel annunciator. The fuel tank incorporates a vent tube at the top of the tank to allow atmospheric air pressure to enter the tank. The operator had marked fuel quantity level lines on the exterior of the tank depicting fuel level, and percent of fuel at each line. A postaccident examination of the engine revealed no mechanical abnormality. A functional test of the fuel probe was not completed due to damage received in the accident.

Verbatim NTSB analysis and probable cause from the NTSB dataset