The Federal Aviation Administration has finalised a national transition plan to phase out leaded 100LL aviation gasoline for piston aircraft, setting a four-stage roadmap that moves the United States toward unleaded avgas while leaving major implementation details unresolved. The plan targets the end of leaded fuel use outside Alaska by 2030 and in Alaska by 2032, but the agency has not fixed detailed schedules for the later phases.
The first phase focuses on fuel authorisation and comparison testing, with the FAA set to evaluate GAMI G100UL, Swift Fuels 100R and LyondellBasell/VP Racing Fuels UL100. The tests will cover engine performance, detonation resistance, material compatibility and fuel composition, including behaviour when fuels are blended with 100LL or mixed with each other. Phase 1 is expected to finish in spring 2027, followed by an updated plan later in 2027.
The agency plans to start rulemaking during Phase 2 to establish unleaded avgas standards and the regulatory framework for ending leaded-fuel sales. It estimates producers will need capacity to replace about 180 million gallons of annual 100LL demand, and identifies cost, liability and schedule as the main risks. Approval of an unleaded fuel will not automatically clear every aircraft for use; some types may need placards, logbook changes, revised operating information or hardware modifications.