Finding an unleaded avgas solution is a tremendously complex issue in which changing one piece of the puzzle has consequences—potentially good, but also potentially devastating—throughout the rest of the puzzle.
Why has the general aviation industry waited so long to get engaged in the issue of leaded avgas?
While this issue may appear new to many because of recent EPA activity including the advance notice of proposed rulemaking, it is not new to aviation associations or engine and airframe manufacturers, who have been involved for years.
AOPA and its fellow general aviation associations have been actively involved in the aviation fuel issue since passage of the Clean Air Act in 1970 and the act’s amendments during the 1990s. For many years, that advocacy was to make sure that safe, effective aviation fuel remained available while the FAA and industry sought the elusive “drop in” solution—an additive or fuel blend that did everything that avgas with tetraethyl lead (TEL) does without the environmental consequences. An industry-wide effort led to the development and testing of potential replacement fuels, spearheaded by the Coordinating Research Council (CRC) and the standards organization ASTM. The CRC has tested 200 high-octane fuels, 45 of which included full-scale engine tests. None of these potential alternatives would have sufficiently met the needs of the existing fleet of aircraft. It has therefore become obvious that a drop-in solution does not exist.
Now work focuses on fuels that may meet the anti-knock properties of TEL, but are “near drop-ins” in other areas. And it is these differences in the other areas—such as weight, freezing point, and boiling point, to name but a few—that must be understood in order for the industry to decide on a replacement.
For years, AOPA has also actively pursued funding for critical components of FAA resources that are needed to test new fuels—including work with Congress to secure funding for the William J. Hughes Technical Center fuels facility. Without the intervention of AOPA and other industry groups, this facility, which is the FAA’s only facility for piston-engine fuel testing, would likely have closed due to budget cuts. AOPA has also regularly published progress reports on new fuels.