NATA Cites ASTM D8631-25 As Key Milestone In Unleaded Avgas Evaluation

The National Air Transportation Association (NATA) welcomed the publication of ASTM D8631-25, calling it an important step in the evaluation of UL100E unleaded aviation gasoline.

Issued by ASTM International in November, ASTM D8631-25 establishes the first ASTM specification for UL100E, the unleaded avgas jointly developed by LyondellBasell and VP Racing Fuels. UL100E is currently undergoing evaluation by the Federal Aviation Administration (FAA) under the agency’s Piston Aviation Fuels Initiative (PAFI), in coordination with aircraft and engine manufacturers. Completion of PAFI testing is anticipated by September 2026.

NATA President and CEO Curt Castagna said the publication of the standard reflects meaningful progress toward a commercially viable unleaded aviation fuel. He noted that an ASTM standard specification is a prerequisite for a fuel to advance through FAA evaluation and consideration under PAFI, reinforcing the importance of structured, ASTM-based processes to support innovation while maintaining safety and operational certainty.

PAFI is overseen by a collaborative industry and government group of technical experts and evaluates candidate fuels across multiple criteria, including detonation, durability, performance, and materials compatibility. Test data and results are shared with engine and airframe original equipment manufacturers to support confidence in the fuel and to inform development of an ASTM production specification.

NATA said it will continue supporting its members and the broader aviation community through education, advocacy, and technical resources as part of the joint FAA and industry EAGLE Initiative (Eliminate Aviation Gasoline Lead Emissions) effort to enable a safe transition to unleaded avgas.