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The AOPA has tested unleaded avgas on a Beechcraft Baron demonstration aircraft, shown on display at EAA AirVenture Oshkosh in 2024.
Developers of a candidate high-octane unleaded aviation gasoline for piston-engine aircraft say they have cleared a major hurdle toward commercialization with the publication of an industry-standard test fuel specification of their formulation.
VP Racing and LyondellBasell announced on Jan. 5 that standards organization ASTM International has issued a first specification for their UL100E unleaded avgas. ASTM published the D8631-25 “Standard Specification for Unleaded Aviation Gasoline Test Fuel Containing Ethers” in November.
Under development by the partners since 2018, UL100E is undergoing full-scale testing by the FAA, engine and aircraft manufacturers under the Piston Engine Aviation Fuels Initiative (PAFI). VP Racing expects the PAFI testing will be completed by September, which could lead to an FAA fleetwide authorization of the unleaded avgas.
“The FAA will use the PAFI test results to define the eligible fleet and outline any operational and/or engine modifications required for a small portion of the fleet via a Special Airworthiness Information Bulletin,” San Antonio-based VP Racing said.
Trade groups representing general aviation pilots and fuel suppliers welcomed the development.
“The publication of ASTM D8631-25 reflects meaningful progress for UL100E and the broader effort toward a commercially viable unleaded aviation fuel, affirming the extensive technical work led by LyondellBasell and its partners,” said Curt Castagna, National Air Transportation Association president and CEO. “An ASTM standard specification is a prerequisite for a fuel to advance through evaluation and consideration under the FAA’s PAFI initiative.”
The issuance of a test specification allows work toward proving the performance of a high-octane unleaded avgas “to continue under a structured, industry-recognized framework focused on safety, performance, and compatibility with the existing fleet,” the Aircraft Owners and Pilots Association (AOPA) said.
“This is a meaningful milestone as the aviation industry continues to make progress toward an unleaded future,” said AOPA President and CEO Darren Pleasance.
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