Field Reports Highlight Need for Owners to Assess E-AB Aircraft Prior to Using G100UL

Recent news reports and forum posts have brought to light potential concerns experienced by aircraft using G100UL avgas, an unleaded high-octane fuel supplied by General Aviation Modifications, Inc. (GAMI) that is now for sale at two airports in California. GAMI and the FAA are investigating reports of damaged paint and degradation of fuel tank sealant on both certified and experimental amateur-built aircraft (E-AB).

G100UL has been authorized by the FAA for use in most certified aircraft through the issuance of an Approved Model List Supplemental Type Certificate (AML STC). It is important for owners of E-AB aircraft to remember that STCs only apply to type-certificated aircraft. E-AB aircraft do not have type certificates and, thereby, are not covered by an STC. It is also important for our community to understand that some of the materials found on E-AB aircraft are not used in type-certified aircraft and, therefore, may not have been considered in the STC process. Testing protocols for STCs are proprietary, and to date a list of materials tested has not been shared with owners and operators.

As the builders and owners of E-AB aircraft, we are in the unique position of making our own determination with regard to the use of any new fuel. These industry reports highlight the need for each owner to assess the potential impact of using G100UL or any other new fuel on their aircraft before they introduce it to their tanks. This should include a review of the materials used throughout their fuel systems, including fuel tank sealants, gaskets, O-rings and hoses, as well as any other materials which could come into contact with the fuel either through normal operation or in the event of a spill or leakage. To assist users of G100UL, GAMI has provided Installation Instructions, Instructions for Continued Airworthiness and Routine Refueling Hygiene recommendations with additional information.