What happened
While operating in cruise flight, the engine of the aircraft began running rough and experienced a progressive loss of power. As the power loss continued, the pilot was unable to maintain altitude. In response to the deteriorating engine performance, the pilot selected a hillside as an emergency landing site.
During the course of the emergency landing, the airplane's fuselage sustained substantial damage.
The investigation
On July 1, NTSB personnel conducted an examination of the engine at Wick Air, Inc. in Wasilla, Alaska. This examination revealed no anomalies in the engine prior to the accident. Subsequently, on September 11, FAA personnel operated the engine while installed on the airframe and reported that the engine functioned normally at idle power.