FAA Releases Plan for Transition to Unleaded Avgas

As required by the 2024 FAA Reauthorization Act, the FAA has released “The Transition Plan to Unleaded Aviation Gasoline.” This initial version of the plan will be updated as new information is incorporated and phases of the plan are completed.

Phase 1 requires completion of FAA approvals and authorizations for the three candidate unleaded fuels that have been fielded or are under development. “Phase 1 also includes comparison testing and reporting to facilitate more informed decision-making by the end users,” according to the FAA. 

The three fuels in Phase 1 are GAMI’s G100UL, which has been supplemental type certificate (STC)-approved for all spark-ignition piston aviation engines; Swift Fuels 100R, STC-approved for several engines but not yet for high-performance engines that require the detonation-protection features in 100LL; and LyondellBasell/VP Racing’s UL100, for which the companies hope to gain an FAA fleet-wide approval later this year covering certain aircraft and engines but not yet high-performance detonation-sensitive engines.

The FAA and industry have partnered on the transition to unleaded avgas through the Eliminate Aviation Gasoline Lead Emissions initiative. As part of this effort, the FAA is testing the three fuels at its William J. Hughes Technical Center in Atlantic City, New Jersey. This testing is “part of the first phase of the transition to address key questions concerning performance and compatibility,” and the FAA will update the transition plan after this phase is done.

Meanwhile, both Swift Fuels and LyondellBasell/VP Racing are working with the FAA under the Piston Aviation Fuels Initiative on the fleet authorization program. The FAA is also working to expedite rollout of high-octane unleaded fuel using the STC pathway, for both GAMI’s G100UL (which is already STC-approved for high-octane engines) and Swift’s 100R.

During the transition to unleaded avgas, which is supposed to happen by the end of 2030 in the continental U.S. and 2032 in Alaska—although the FAA has indicated that these deadlines may slip—the FAA is “encouraging airports to introduce unleaded fuel alternatives while requiring maintaining 100LL availability for aircraft through the transition.”

The FAA is also holding airports to grant assurance obligations that require them to “continue to offer leaded 100LL until safe, fleet-wide unleaded alternatives are widely and locally accessible.”