IAD05LA035 · Aeronca S7CCM

The airplane's fuel tanks contained a mixture of 100 low lead aviation gasoline and automotive gasoline. During the preflight examination of the ski-equipped airplane, the pilot preheated the engine for about 30 minutes, and drained fuel samples from the fuel system. The samples were all absent of water or debris. The engine was started, and allowed to idle for about 15 minutes, and following taxi, a complete run-up check was performed. During the initial climb, at an altitude about 50 feet AGL, the engine began to lose power and run roughly. The pilot elected to turn the airplane toward a field and an up-sloping hill. He flew the airplane across an approximately 420-foot long field, and touched down below the top of it. The airplane then became airborne again after crossing the crest of the hill. The airplane descended "at near stall speed," and as the pilot rolled the airplane into a steep bank to avoid trees, the left wing contacted the ground. The airplane pivoted to the left, and impacted a large fence. According to the passenger, the airplane's engine was running for the duration of the flight, and upon inspection after the accident, the throttle was found in the full open position. Examination of the airplane's engine revealed no mechanical anomalies. Review of a carburetor ice probability chart revealed that with a temperature of 27 degrees Fahrenheit, and a dewpoint of 19 degrees Fahrenheit, the conditions were conducive for light carburetor icing at cruise or glide power.

Verbatim NTSB analysis and probable cause from the NTSB dataset