What happened
While operating over mountainous terrain, the pilot reported that the engine began running roughly. The pilot identified a large, snow-covered meadow below and began circling the area in an attempt to resolve the engine issue. Despite efforts to regain full power, the pilot was unsuccessful.
Because the aircraft was equipped with large tundra tires, the pilot determined that a precautionary landing under partial power was more prudent than attempting to cross mountain ridges and fly over surrounding forests to reach the nearest airport. During a wheel landing in the snow, the aircraft nosed over and came to rest in an inverted position. The pilot was not injured.
The investigation
The inspection of the aircraft revealed structural damage, including bending of the forward section of the airframe, both wing spars, and the vertical stabilizer. The cause of the partial power loss remained undetermined.