What happened
A witness located approximately two miles from the accident site reported hearing an approaching airplane with an engine that was sputtering as if it were missing. The witness heard a loud "pop" but did not see the aircraft. Upon moving to a clearing, the witness observed a fire on the mountainside. At the time of the event, the sky was overcast and the mountaintops were obscured. The point of impact was estimated to be 500 feet below the overcast layer.
The investigation
Following the recovery of the wreckage, the engine was disassembled and inspected. Investigators found no anomalies during the examination; the camshaft and crankshaft maintained continuity, and all connecting rods remained attached. The carburetor had separated from the engine during the event. Upon inspection, the carburetor bowl was found to be empty and the throttle valve was in the closed position. Both the engine-driven fuel pump and the auxiliary fuel pump were destroyed by fire.
Findings
Weather data from the nearest reporting station, located 37 miles south of the accident site, indicated temperatures and dew points conducive to serious icing at cruise power. Additionally, the temperature and dew point conditions recorded at both the departure and destination points were conducive to serious icing at glide power.