What happened
During the takeoff climb, the engine of the aircraft failed. The engine subsequently restarted; however, as the pilot turned the aircraft to the north, the engine failed a second time. This second failure resulted in an aerodynamic stall, causing the aircraft to crash into a wheat field.
The investigation
Investigators examined the fuel system and found that the aircraft was operating under a Supplemental Type Certificate (STC) for the use of automotive gasoline. The fuel contained water and rust contaminants, and the fuel lines were found to be dried.
Examination of the carburetor revealed a composite float. The spark plugs and the carburetor throat showed evidence of soot. It was noted that composite floats are no longer produced by the manufacturer and the Airworthiness Directive (AD) previously requiring their use has been rescinded.
Findings
Technical literature, including FAA Advisory Circulars, the FAA Accident Prevention Program, Piper Service Bulletins, and Lycoming newsletters, all highlight the lack of uniform standards for automotive gasoline and the issues associated with inadequate fuel standards. Additionally, the FAA has noted that the use of automotive gasoline can allow for carburetor icing at higher temperatures.