Accident Sequence
The pilot was flying between 800 and 1,000 feet above the trees in mountainous/hilly terrain. He decided to add power and start a climb up the valley he was in. Just as he added power, the aircraft's engine rpm dropped from about 2,300 to about 1,800 to 1,900 rpm. The pilot then applied full carburetor heat, moved the mixture to full rich, and checked the fuel selector position. According to both the pilot and his passenger, these actions did not restore engine rpm, which stayed near 1,800 rpm. Because the terrain was rising and the aircraft could not maintain altitude, and because they were already very low, the pilot made the decision to attempt a forced landing in the densely forested snow-covered mountainous terrain. While attempting the landing, the aircraft struck a number of trees, then impacted the snow-covered ground in an inverted position.
Investigation
A post-accident inspection of the airframe, systems, and engine did not reveal evidence of any pre-impact anomalies or malfunctions that would have precluded the engine from operating at full power.