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NAS Report Confirms 100LL Unleaded Replacement Complexities

January 14, 2021 – The complexities and difficulties regarding developing high-octane unleaded aviation fuel alternatives were confirmed by the National Academy of Sciences on Tuesday, as it released a report that studied how to reduce lead emissions and exposure from aviation fuel. The report recommends a multi-path approach to lead reduction included many findings outlined previously by EAA, which has been involved in advocating for possible unleaded alternatives for nearly 50 years.

In the report, Options for Reducing Lead Emissions from Piston-Engine Aircraft, the NAS notes the environmental and health implications of lead use, but also recognizes the complex marketplace, technological, and economic barriers to a "drop-in" solution. EAA was asked to provide input during the early stages of the report, as the association has been involved with leaded fuel alternatives beginning with EAA's groundbreaking unleaded auto-fuel research in the 1970s.

The NAS also noted that simply eliminating 100LL is not a viable option, given the importance of general aviation aircraft that use the fuel to the nation's transportation system. In addition, the inability of GA aircraft to use auto fuel containing ethanol eliminates that option due to the effect of ethanol-blended fuels on aircraft systems and operational safety.

"The National Academy of Science research group reiterated what EAA has been saying for many years – that working toward a viable fleet-wide replacement for 100 low-lead fuel is the only complete solution, but that despite concerted effort, formidable technological barriers have prevented success thus far," said Sean Elliott, EAA's vice president of advocacy and safety. "It is our hope that this study will assist Congress, the FAA, and other government agencies in better understanding the challenges we face in eliminating lead from aviation fuel and encourage them to dedicate the resources necessary to help make that outcome a reality."

The NAS report recommends a variety of near-term solutions to incrementally reduce lead emissions and exposure, while research continues into an eventual 100LL replacement. Those recommendations include operational and education initiatives, public policy and economic support for making lower octane fuels available for those aircraft that can use it, continuing to work toward development of a 100LL replacement, near-term implementation of 100VLL (very low lead) that EAA supported as an ASTM specification, possible prohibition on the manufacture of new aircraft at some future date that cannot also use a lower octane fuel, and continued R&D on alternative propulsion systems such as diesel, electric, and others.

Over the past decade, EAA pressed for the creation and has helped manage the Piston Aviation Fuels Initiative (PAFI), a joint government-industry effort to evaluate and authorize the use of high octane unleaded fuels. EAA also supported the development of the 100VLL standard and encourages its use where possible, as much of the existing 100LL fuel in the marketplace already meets the 100VLL reduced lead content requirements.

"PAFI provides the only means of bringing together all of the stakeholders necessary to develop, test, evaluate, and recommend fleet authorization for a high-octane unleaded aviation fuel for GA," Elliott said. "We urge that Congress, FAA, and other government agencies step up to help provide adequate resources to this important effort designed to keep general aviation aircraft viable and safe far into the future."

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