Incident Description
The pilot, accompanied by his brother, was operating the helicopter on an extended cross-country flight that passed through mountainous terrain. After approximately one hour of flight, while maintaining an altitude of 8,000 feet, the pilot perceived an alteration in the engine's sound and the aircraft subsequently suffered a partial reduction in power. In response, the pilot initiated an autorotation maneuver with the intention of landing on a snow-covered area. Upon making contact with the ground, which was on a steep incline, the helicopter began to slide downhill and eventually collided with trees.
Investigation Results
Following the event, investigators examined the helicopter. They found that one of the magnetos was not operating properly. The investigation report noted this magneto malfunction but did not explicitly link it to the partial power loss or the chain of events.