Overview
- ASTM International published D8631-25 in November 2025, creating a formal test specification for unleaded avgas containing ethers that guides the FAA’s ongoing evaluations.
- UL100E, co-developed by VP Racing and LyondellBasell, remains the only fuel in the FAA’s fleet-approval pathway and is undergoing coordinated engine, aircraft, and Technical Center testing.
- VP Racing says PAFI testing of UL100E is expected to conclude by September 2026, after which the FAA will review results for potential fleet authorization decisions.
- Recent milestones include material compatibility testing by manufacturers and at the FAA William J. Hughes Technical Center, with endurance and detonation runs on large-block Lycoming and Continental engines and ongoing flight tests on a Lancair Super Legacy and a Harvard Mk IV.
- AOPA welcomed the progress and said the test results will inform FAA decisions on eligible aircraft and any operational or engine modifications, as the industry works toward unleaded transition goals for 2030 in the lower 48 and 2032 in Alaska.