Accident Details
During a touch-and-go takeoff, the engine sputtered, emitted black smoke from the exhaust, and experienced a partial loss of power. The pilot reported that the aircraft was too far down the runway to abort, so he continued the takeoff. Subsequently, the aircraft struck a pole near the departure end of the runway and was landed in a field. Hard braking was used to avoid objects during the landing, and the aircraft nosed over.
Investigation Findings
Investigation revealed that a mixture of avgas and autogas had been used as fuel. Soot was found on the #3 and #5 spark plugs. The pilot stated that he had cleared the engine on base leg and that carburetor heat was off momentarily when he applied power for a go-around. Additionally, a Supplemental Type Certificate (STC) had been developed for the use of auto fuel in W-670-6N engines.
Environmental Conditions
About 60 miles west at Hickory, North Carolina, the 1400 EST temperature and dew point were 45°F and 21°F, respectively. According to carburetor ice charts, conditions were conducive for carburetor ice with the engine operating at glide power.