N7185S

On January 4, 1995, about 1453 central standard time, a Cessna 150H, N7185S, nosed over during landing at Fayetteville, Tennessee. The airplane was operated by the owner under the provisions of 14 CFR Part 91, and visual flight rules (VFR). Visual meteorological conditions prevailed. A VFR flight plan was filed for the solo, instructional flight. The student pilot was not injured, and the airplane was substantially damaged. Origination of the flight was Murfreesboro, Tennessee, about 1420, on the same day.

Prior to the flight, the pilot obtained a weather briefing. Due to the weather conditions, the pilot discussed the chances of carburetor icing with his flight instructor prior to departing for his cross country. According to the pilot, while on short final approach, the engine quit.The pilot reported that, during his flight, he experienced carburetor icing several times and had to apply carburetor heat to clear the carburetor ice out of the engine. He stated that he had "only pulled the carb heat out for about 5 to 10 seconds each time". The pilot stated that the last time he pulled carburetor heat, the engine began to run smoothly. About 30 seconds later, the pilot stated that the engine began to "act funny again". The pilot stated that he did not "think about it being carb ice because [he] had never experienced it that fast after pulling carb heat. The engine lost power faster than usual and the engine finally quit." During the forced landing, the right main landing gear contacted a fence post and the airplane nosed over.

The pilot Cessna 150H operating handbook requires the use of carburetor heat on the before landing checklist. It states, "Carburetor Heat -- Apply full heat before closing throttle."

The aircraft owner stated that a single piece venturi had been installed in the aircraft and, ever since then, they experienced problems with carburetor icing. The owner also stated that the aircraft had been topped off with automotive gasoline before the flight and that the aircraft had been approved for operation with automotive gasoline.

The "Airframe & Powerplants Mechanics General Handbook" states that, with the use of automotive gasoline, the carburetor "icing condition is most severe in the temperature ranges of 30 [degrees] to 40 [degrees] F outside air temperature." (page 74). The Federal Aviation Administration issued an advisory circular, 91-33A, regarding the use of automotive gasoline for aviation purposes. The circular states that, "carburetor icing will occur in less time and at higher ambient temperatures with automotive gasoline than with aviation gasoline." (page 3).