July 28, 2009 - Oshkosh, Wisconsin - Monday’s panel discussion on the future of aircraft fuels offered a thorough discussion about the threat to the continued use of leaded aviation gasoline and a view of the process that could lead to the widespread use of unleaded aviation gasoline in the coming years. The result of 19 years of work to find a lead-free substitute for 100-octane, lowlead (100LL) aviation fuel is that there is no solution that offers a seamless transition from leaded to unleaded fuel for high-performance aircraft engines, and viable solutions remain elusive.

EAA, the FAA, the U.S. Environmental Protection Agency (EPA) aircraft, and engine manufacturers and fuel producers have all taken part in that effort. At Monday’s event, about 150 spectators heard from representatives of EAA, EPA, FAA, GAMA (General Aviation Manufacturers Association), the Coordinating Research Council, and the FAA Technical Center who collectively have conducted or coordinated much of the research to date.

“We are no longer seeking a ‘transparent’ or ‘drop-in’ replacement for 100LL—one that wouldn’t require modifications to the aircraft or FAA approval for each aircraft,” said Walt Desrosier, a vice president of GAMA.

Alternatives under study include low- or medium-octane unleaded avgas, high-octane synthetic fuels (mainly biofuels), and new blended fuels. The solution has to be a worldwide standard, panel members agreed, and it has to be a long-term solution. “A solution that lasts two to three years is no solution,” said EPA’s Glenn Passavant.

High-performance aircraft engines— powering about 30 percent of the U.S. general aviation fleet—are designed to use leaded fuel to control engine detonation.

Any potential alternative to 100LL will require extensive testing to determine its effects on the engine and fuel system, aircraft systems and performance, as well as engine cooling and weight. In addition, researchers will have to identify certification issues and the costs of the fuel, as well as needed aircraft modifications.

Time is running out, Passavant noted; states will need to meet the new lead air quality standard by 2016 or 2017, and aviation gasoline may need to be part of the solution.

Finding a solution, panel members agreed, remains a complex problem. A forum exploring the declining availability of fuel for light-sport aircraft and other auto-fuel-powered aircraft will be held at 10 a.m. in the Aviation Learning Center, Stage 2. The center is supported by Chevron.