Avgas: Beyond the 'silver bullet'
It sounded like the perfect additive. Researchers at the Ethyl corporation, a General Motors subsidiary, discovered in 1921 that adding a small amount of tetraethyl lead to fuel silenced the knock that could cause an engine to tear itself apart during operation.
The discovery of lead as a cheap octane-booster paved the way for high-power, high-compression engines and carried the United States automotive industry through 50 years of production. Tetraethyl lead made possible the development of powerful engines for such classic American aircraft as the P-51 Mustang and the B-29 Superfortress, powerhouses that contributed to the Allied victory in World War II.
But the performance benefits of the additive came at a cost.
The Environmental Protection Agency (EPA) concluded in 1973 that lead from automobile exhaust was posing a threat to public health and moved to regulate it under the Clean Air Act, gradually reducing the lead in auto fuel and then eliminating it completely. When the agency took the last steps in the phaseout decades later, EPA administrator Carol Browner called the elimination of lead from auto fuel “one of the great environmental achievements of all time.” Now, American aviation is expected to follow suit.
For 20 years, the GA industry has been looking for a fuel that has all the benefits of the current avgas that uses tetraethyl lead but none of the drawbacks. To date, no fuel has been proven to match 100LL point for point, although research at a number of companies continues. As the EPA takes preliminary steps toward the setting of emission standards that will ultimately lead to the removal of lead in avgas, industry groups are developing a path for all options, including those currently in development, to be vetted across a spectrum of cost, availability, ease of production, performance, and environmental impact.
AOPA, the American Petroleum Institute (API), the Experimental Aircraft Association (EAA), the General Aviation Manufacturers Association (GAMA), the National Air Transportation Association (NATA), the National Business Aviation Association (NBAA), and the National Petrochemical and Refiners Association (NPRA) recently formed a coalition to work with industry, the FAA, and the EPA to address the challenges of finding an avgas replacement. The coalition is gathering data now that will help it develop the criteria for evaluating fuels and a plan for the transition once a new fuel is available. In the meantime, the coalition is committed to working with the rest of the aviation industry and government agencies to make sure GA continues to have an adequate supply of 100LL until such time as the transition is complete.
All aircraft and aircraft owners could be affected by the transition to an unleaded fuel. Any viable fuel must address questions of cost, availability, ease of production, performance, and environmental impact for a wide variety of GA aircraft. The issue is much more than just achieving an octane number. The industry and the EPA need a better picture of how the transition will affect all GA aircraft; owners and pilots can explain how the transition will affect them in comments to the EPA’s advance notice of proposed rulemaking (EPA-HQ-OAR-2007-0294-0100).
“Understanding all the options is the first step to finding an alternative to leaded fuel,” said AOPA President Craig Fuller. “We need to establish a process that considers all factors. With leadership from the FAA and the involvement of all stakeholders, I’m confident we can find a solution.”
July 1, 2010