23 March 2026
The US Federal Aviation Administration (FAA) has significantly expanded approval for Swift Fuels’ 100R unleaded avgas, marking another step towards a long-awaited replacement for 100LL.
An updated supplemental type certificate (STC), published on 11 March, adds a greatly enlarged approved model list (AML), allowing the fuel to be used in hundreds of piston engines. The expansion covers 88 engine types and around 840 individual models, ranging from small 65hp Continental units to larger Lycoming 540-series engines.
The detailed nine-page AML document shows the breadth of the approval, including a wide mix of Continental, Lycoming, Franklin and Pratt & Whitney engines, as well as a number of radial powerplants.
Swift’s 100R is a 100-octane unleaded fuel intended as a direct replacement for 100LL. Until now, its use had been limited to a small number of aircraft — primarily fuel-injected Cessna 172R and S models —operating under the original STC.
The expanded approval brings 100R much closer to broader operational use, particularly as Swift aims to leverage existing infrastructure already supplying its lower-octane UL94 fuel, now available at more than 100 airports worldwide.
However, some notable gaps remain. High-compression and large-bore engines such as Continental’s 550-series are not yet included, with certification work ongoing. Swift has previously indicated that these more demanding engine types are being pursued under parallel approval programmes.
The company is also working towards further approvals for turbocharged and radial engines, as well as continuing real-world testing through flight school operations, where 100R has reportedly performed well.
Swift’s fuel is one of several contenders in the race to replace leaded avgas. While GAMI’s G100UL has already secured fleetwide approval, its availability remains limited. Other formulations, including a fuel under development by LyondellBasell and VP Racing, are progressing through testing and certification.
