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.