WPR10LA149 · Schafer STARDUSTER SA-300

After being airborne for about 10 minutes, the pilot applied full carburetor heat as he entered an area that he felt had high humidity. About five minutes later the airplane's engine, a 220 horsepower Continental W670 radial, began to lose power. Although the pilot managed to keep it at cruise power for a short period of time by pumping the throttle, the engine then slowly lost all power. The pilot was forced to execute an emergency landing in a rough log-covered clear-cut in the forest. Upon touchdown, the airplane cartwheeled and came to a stop within about 100 feet. A post-accident inspection of the airplane's fuel system, ignition system, and air induction system did not reveal any evidence of a malfunction or anomaly that would have kept the engine from producing cruise power. The airplane had about 28 gallons of fuel in its tank at takeoff, and the pilot said that he had flown the airplane many times in the high humidity conditions found near the ocean, and that with the full application of carburetor heat; the airplane's carburetor had never accumulated ice in its throat. The reported temperature and dewpoint (14 and 7 degrees C respectively), when plotted on a carburetor icing probability chart, fell in the area annotated "Moderate Icing Cruise Power or Serious Icing Descent Power".

Verbatim NTSB analysis and probable cause from the NTSB dataset