Accident Overview
A helicopter experienced an engine power loss after the private pilot flew through an area of moderate to heavy snow. The pilot initiated an autorotation and landed in a field. During the landing, the application of excessive aft cyclic caused the main rotor blades to flex downward and sever the tail boom.
Events
According to the pilot, the engine lost power while the helicopter was in flight. The helicopter was equipped with an automatic engine re-ignition and engine failure warning system, which was required by the rotorcraft flight manual (RFM) for operation in falling or blowing snow. The pilot stated that the system was armed at the time of the engine failure. The engine-out warning light illuminated before the power loss, accompanied by an audible tone.
Weather and Fuel
Weather reported in the area included snow and freezing fog, with a temperature of 16 degrees Fahrenheit. The RFM prohibited flight into known icing conditions. It also required that fuel meet the anti-icing capability of JP-4 when operating at 40 degrees or less. A review of fueling records revealed that no anti-icing additive was added to the fuel.
Examination
An examination of the engine found no mechanical anomalies. The cause of the power loss remains undetermined based on the available information.