The Federal Aviation Administration (FAA) has called for samples of unleaded fuel to be considered as potential replacements for 100LL avgas.
The FAA program will assess the viability of candidate fuels in terms of impact upon the existing fleet, production and distribution infrastructure, environment and toxicology, and economic considerations.
Leaded avgas has been used in aircraft under an exemption from the unleaded gasoline regulations because a suitable alternative was not available. Environmental lobbyists in the USA have been putting pressure on the government to halt the use of lead in avgas.
The aviation industry in the USA has widely applauded the FAA's call, saying that an unleaded avgas is desirable.
General Aviation Manufacturers Association (GAMA) President and CEO Pete Bunce said: “GAMA is very pleased that the FAA has taken this important step toward identifying replacement unleaded aviation fuels to ensure the continued safety of existing general aviation aircraft.
"We look forward to continuing to work with the FAA and other industry partners on this critical issue.”
One of the major issues has been the need to find a "drop-in" substitute for 100LL that would mean the entire GA fleet would not have to be re-certified. That hope appears to have been abandoned now.
In 2012, a US committee called the Unleaded Avgas Transition Aviation Rulemaking Committee (UAT ARC) developed a fuel development road map, which included the recommendation to set up a Fuels Program Office within the FAA.
The Fuels Program Office is driving the search for an unleaded gas for eventual fleet-wide deployment. Should they be successful, the demand for 100LL will fall to the point where manufacturers will offer the new fuel only, with flow-on effects for the Australian GA fleet.