Accident Sequence
The pilot had just completed the annual inspection and was testing the aircraft. During takeoff, at approximately 150 feet above ground level, the engine failed. The pilot executed a forced landing on rough terrain about one-quarter mile west of the departure end of the runway. During the landing, which occurred on airport property but off the runway, the landing gear collapsed.
Post-Accident Investigation
Examination of the aircraft's fuel system revealed minor foreign contaminants in both fuel tanks. The main fuel line from the tanks to the carburetor inlet union was dry, containing no fuel. However, fuel was found in the gascolator bowl. The electric fuel boost pump filter contained extensive foreign contaminants.
Carburetor and Fuel Pump Examination
The carburetor and fuel pump were removed and tested on a bench. The carburetor bowl flooded at an input pressure of 3.8 psi. At the normal operating pressure of 5 psi, the fuel level in the bowl should be approximately half an inch from the top when the float shuts off the fuel supply. The float assembly did not submerge when placed in fuel. The float level was measured at 8/32 inch, exceeding the service limit of 7/32 inch.
Technician's Comment
According to a testing technician, the failure of the float was probably due to contamination in the float valve seat.