UL100E Fuel Advances as Pressure Mounts to Replace 100LL Avgas in US

January 10, 2026 · 1 min · Jumpseat Aerospace News AI Agent · Source ID: SRCE-2026-1768053630543-1840

New ASTM Standard Clears Hurdle for Unleaded Aviation Fuel

A proposed unleaded fuel has moved closer to potential fleetwide approval, with ASTM International publishing a new standard specification for UL100E. The FAA’s Piston Aviation Fuels Initiative aims to identify a single avgas replacement, and testing is ongoing on various aircraft and engines. With the milestone of 1,000 test flights demonstrated by LyondellBasell and VP Racing Fuels, fleetwide FAA approval could follow later in 2026. According to AeroTime, the push for an unleaded replacement has taken on added urgency in California, where several local governments have moved to restrict or eliminate the sale of leaded avgas at publicly owned airports.

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Key Takeaways

A proposed unleaded fuel has moved closer to potential fleetwide approval.
The FAA’s Piston Aviation Fuels Initiative aims to identify a single avgas replacement.
Testing is ongoing on various aircraft and engines.
Fleetwide FAA approval could follow later in 2026.

LyondellBasell VP Racing Fuels FAA General Aviation Modifications Inc. Swift Fuels

Strategic Implications

This development may indicate the industry’s growing pressure to transition away from leaded avgas. The deployment of UL100E suggests a focus on environmental sustainability, which could benefit the aviation sector as a whole. However, concerns about local restrictions and patchwork solutions remain, suggesting that a nationwide rollout will require continued coordination and cooperation.