What documentation is required for a certificated aircraft to legally operate on automotive gasoline?

• A. There must be a Supplemental Type Certificate (STC) for the aircraft to operate on automotive gasoline.
• B. No documentation is required.
• C. A standard airworthiness certificate is sufficient.
• D. A special flight permit is required, not an STC.

Answer: (A)

Using automotive gasoline in a certificated aircraft requires FAA-approved authorization for that specific fuel, typically in the form of an STC. The STC provides the approved modification to the fuel system or engine and includes the fuel type, octane requirements, any additives or restrictions, and the operating limitations. Because changing the intended fuel is a significant alteration to the aircraft’s approval basis, it must be documented in the aircraft’s records and follow the data of the STC. Without this FAA-approved modification, operating on automotive gasoline would not be legal.

A standard airworthiness certificate alone does not authorize fuel types beyond what the type certificate and approved documents specify, so it isn’t sufficient. A special flight permit is for limited, temporary, or experimental situations and is not the mechanism to authorize a fuel-type change for a certificated aircraft. And stating that no documentation is required is incorrect because changing fuel requires formal FAA-approved documentation.