FAA Investigates Damages to Paint and Fuel Tank Sealant

General Aviation Modifications, Inc. (GAMI and the FAA are investigating reports of paint and fuel tank sealant damage from aircraft using G100UL avgas. The alternative fuel is currently offered at two California airports for certified and experimental amateur-built (E-AB) aircraft.

GAMI’s G100UL is an unleaded, high-octane fuel that has been granted an FAA Approved Model List Supplemental Type Certificate (AML STC). This type of approval essentially allows for a small initial list of aircraft and engines to be expanded to other variations over time.

However, G100UL’s type certificate only applies to aircraft that have a type certificate of their own. Since E-AB aircraft are not type-certified, they can not be listed on the fuel’s Approved Model List. This means that certain materials used in experimental aircraft may not have been previously tested with G100UL and could react poorly when using it. Users have already begun to notice this issue, reporting incidents of peeling paint and leaking fuel tanks.

“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,” the Experimental Aircraft Association (EAA) explained. “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.”

The EAA suggests that homebuilders check materials used in fuel systems, fuel tanks, gaskets, hoses, and any other components that would interact with GAMI’s fuel. Users can also check GAMI’s Installation Instructions, Instructions for Continued Airworthiness, and Routine Refueling Hygiene recommendations for further advice.

G100UL first became steadily available in October 2024 at Reid-Hillview Airport (RHV), located in San Jose, California. Santa Clara County signed an agreement with G100UL’s producer, Vitol, for the purchase. The truck-to-airplane delivery costs $6.99 per gallon.

“Offering G100UL to our airport users has been years in the making,” stated Eric Peterson, the Director of County Airports. “This fueling alternative positions RHV as the first airport in the nation to offer unleaded aviation fuel for the entire general aviation community and we are pretty excited about that.”

FMI: https://g100ul.com