A fuel under evaluation as a replacement for leaded avgas for the 170,000 aircraft in the piston-powered general aviation fleet will need “additional refinement,” and three new fuels have undergone preliminary testing in 2019, the FAA said in an update on its Piston Aviation Fuels Initiative.
AOPA participates in the PAFI program as a member of the PAFI Steering Group (PSG), and supports the ultimate goal of approving a high-octane, unleaded avgas that will be “environmentally safer than leaded fuels, yet as operationally safe as leaded fuels in the current fleet of piston engine aircraft.” In October 2018 the FAA had forecast a completion-of-testing target date of mid-2020. The timeline estimate was based on testing a fuel under development by Shell—now the lone participant in the PAFI process after another entrant, Swift Fuels, withdrew. At the outset of the PAFI process in 2014, 17 fuels had been submitted for analysis, which the program “screened down” after a rigorous evaluation process.
According to the June 2019 program update, “PAFI’s focus during the first 6 months of 2019 has included testing at the William J. Hughes Technical Center of an optimized Shell fuel and screening testing of 3 fuels not previously part of the PAFI program. The scope of PAFI has continued to evolve with the preliminary evaluation of 3 other fuels representing PAFI’s commitment to research and evaluate all candidate unleaded fuels. Test results with the optimized Shell fuel were not successful with testing indicating additional refinements are required.”
As the program to bring about a safe transition to an unleaded avgas has evolved, experience “has served to accentuate the extent of the challenge to identify an acceptable unleaded fuel for general aviation. Accordingly, it is recognized that the scope of PAFI must expand to support the necessary research and development while engaging other candidate fuels for evaluation,” the FAA said, calling for continued support for PAFI as “a collaborative government and industry process.”
The FAA update concluded by noting that “the FAA and industry members of the PAFI Steering Group continue to work with multiple fuel offerors to find the very best unleaded avgas solution for the GA fleet.” It said its determination to find an environmentally friendly fuel has not wavered, “regardless of the amount of time and effort it may take to achieve.”