Unleaded Avgas Candidate Passes Critical Engine Tests, Moves Ahead

UL100E fuel produced by LyondellBasell/VP Racing is first to pass the 150-hour durability test under PAFI.

The piston GA fleet is moving toward an unleaded future. [Credit: iStock]

Encouraging news about unleaded aviation fuel arrived from the FAA on Wednesday. The agency cleared the unleaded UL100E avgas developed by LyondellBasell Industries/VP Racing for piston-engine aircraft to move ahead to full-scale engine and flight testing.

The announcement came after the fuel passed a 150-hour engine durability test under the Piston Aviation Fuels Initiative (PAFI), a collaborative industry and government testing program established in 2014. The FAA noted that the LyondellBasell/VP Racing UL100E is the first unleaded fuel to pass this phase of PAFI testing. The program’s signatories are working towards a replacement for 100LL avgas for aircraft requiring higher octane than the currently available 94UL unleaded fuels.

“This is another important milestone for a safe general aviation transition to unleaded fuel and for our goal to eliminate lead emissions by the end of 2030,” said Lirio Liu, FAA executive director of aircraft certification service and government co-chair of the Eliminate Aviation Gasoline Lead Emissions (EAGLE) government-industry partnership. “The joint industry/government effort continues to make strong progress.”

The General Aviation Manufacturers Association (GAMA) and Aircraft Owners and Pilots Association (AOPA), both members of EAGLE, said they are “applauding the news of the first unleaded fuel candidate to successfully pass the most rigorous Piston Aviation Fuels Initiative initial detonation and 150-hour engine durability test phase, and continued progress toward an unleaded future.” 

Overall, the PAFI test program evaluates fuel on numerous characteristics including engine durability and detonation, aircraft performance, material compatibility and environmental factors.

“The LyondellBasell/VP Racing’s achievement marks an important waypoint on the path to a more environmentally friendly future for aviation fuel and demonstrates the progress we’ve made through our government and aviation community partnership,” said Curt Castagna, president of the National Air Transport Association (NATA) and industry co-chair of the EAGLE initiative. “EAGLE celebrates this milestone and looks forward to more opportunities to recognize industry ingenuity and innovation.”

The next step for the LyondellBasell/VP Racing fuel includes engine and airframe testing with 10 engines and eight aircraft, which is expected to take 12 to 18 months. The UL100E fuel is one of four unleaded fuel candidates in the test program. If a fuel successfully completes testing, and the American Society for Testing and Materials (ASTM) publishes a production specification, the FAA would issue a fleet authorization.

Jonathan Welsh is a private pilot who worked as a reporter, editor and columnist with the Wall Street Journal for 21 years, mostly covering the auto industry. His passion for aviation began in childhood with balsa-wood gliders his aunt would buy for him at the corner store. Follow Jonathan on Twitter @JonathanWelsh4

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