Alternative Unleaded Fuels for General Aviation Piston Airplanes: A Pathway to Sustainability

Abstract

This study examines the transition from leaded 100 low lead (100LL) aviation gasoline to unleaded alternatives in general aviation (GA) piston-engine aircraft, driven by environmental and health concerns highlighted by the U.S. Environmental Protection Agency's (EPA) endangerment finding. Through a systematic literature review and synthesis, it identifies key unleaded fuel candidates, including 91UL, 94UL (Swift UL94), Auto Gas (Mogas), General Aviation Modification Inc. (GAMI) G100UL, Swift 100R, and LyondellBasell/VP Racing UL100E, evaluating their status, compatibility, advantages, and challenges. The analysis addresses regulatory efforts such as the FAA's Eliminate Aviation Gasoline Lead Emissions (EAGLE) initiative aiming for a lead-free system by 2030, alongside technical, economic, liability, and distribution hurdles. Findings emphasize GAMI G100UL and Swift 100R as promising drop-in replacements for both low- and high-compression engines, underscoring the need for industry collaboration to ensure safety, sustainability, and operational viability in GA for decades to come.