Pressure is mounting to replace leaded avgas, the largest remaining source of lead emissions into the air
SUSTAINABILITY
Within the broader industry movement toward environmental sustainability, pressure is building on general aviation to eliminate the use of leaded avgas by piston-engine aircraft, the largest remaining source of lead emissions into the air.
While the FAA and industry have explored alternatives to leaded avgas for more than a decade, the demand to replace it with an unleaded fuel that could work fleetwide has intensified in the last year. In August 2021, following the release of a study that linked the use of leaded avgas with elevated lead levels in children living near Reid-Hillview Airport (RHV) in San Jose, California, the governing Santa Clara County Board of Supervisors voted to stop sales of 100 Low Lead (100LL) avgas at RHV and San Martin Airport (E16), 25 mi. south of the city as of January 2022. General aviation associations appealed to the FAA to intervene, citing safety risks of the board’s “rushed” decision.
In February 2022, then-FAA Administrator Steve Dickson unveiled the Eliminate Aviation Gasoline Lead Emissions (EAGLE) initiative at the annual General Aviation Manufacturers Association (GAMA) media briefing. The initiative requires industry to accomplish the first two of a four-step approach to eliminating leaded avgas by 2030: first, to build the infrastructure and coordinate production of commercially viable unleaded fuels, and second to support research and testing of needed piston-engine modifications or engine retrofits. The FAA will perform fleetwide testing and qualification of unleaded aviation fuels of different octane levels. Following an expected “endangerment finding” by the U.S. Environmental Protection Agency (EPA) that piston-engine lead emissions contribute to air pollution and may endanger public health, the EPA, through a rulemaking process, would develop a regulatory standard for lead emissions from aircraft engines. The FAA would conduct its own rulemaking process to prescribe standards for the composition of unleaded avgas. “Our fundamental objectives and goals are to assess and evaluate all candidate unleaded fuels that could be potentially viable as a replacement for 100 Low Lead,” says Walter Desrosier, GAMA vice president, engineering and maintenance. “In that, there is a primary desire for something that is going to have the minimum impact on the existing fleet; our goal is something that works as seamlessly as possible for as much of the existing fleet as possible. There is a high priority on something that would be at least 100-octane because that we know is one of the factors that a fuel has to have to work for the existing fleet.”
The U.S. general aviation industry is under mounting pressure to replace leaded aviation fuel used in piston-engine aircraft, the largest remaining source of lead emissions into the air. Credit: Brett Schauf/BCA
Octane, a chemical compound, helps suppress engine “knock” or detonation—an uncontrolled explosion—inside a piston engine’s combustion chamber. The fuel additive tetraethyl lead (TEL) is used to boost octane rating. The higher the octane rating of a fuel, the higher its resistance to detonation. In the U.S., leaded gasoline was gradually phased out and finally banned in 1996 for use in vehicles other than aircraft, race cars, farm equipment and marine engines. Piston aircraft that operate on leaded fuel are the largest remaining source of lead emissions into the air, contributing 70% of the lead being emitted annually, the EPA says. Additional sources of lead emissions into the air include ore and metals processing operations, lead smelters, waste incinerators, utilities and lead-acid battery manufacturers.
A fueling truck delivers 100 Low Lead avgas, a fuel the FAA and general aviation industry have committed to replacing by 2030. Credit: Brett Schauf/BCA
“Years ago, lead was banned from all road vehicles due in part to the severe health consequences of lead exposure,” Rep. Hank Johnson (D-Ga.) said during a U.S. House Aviation Subcommittee hearing July 13 on the state of general aviation. “Today, aviation fuel for piston-engine aircraft is our country’s main and primary source of lead emissions, and the link between piston-engine aircraft and blood-lead levels has never been stronger. Recent research shows a correlation between high levels of lead in children’s blood in relation to proximity to airports.” Turning to GAMA President and CEO Pete Bunce, one of the witnesses testifying at the hearing, Johnson asked: “Mr. Bunce, are you and the manufacturers you represent confident that the EAGLE initiative will succeed?” Bunce replied: “Yes, sir, we are confident.”
However, Bunce added: “The FAA has never done this. We’ve certified engines to operate on a fuel; the FAA has never certified an actual fuel.” Counting The Fleet The EPA cites the FAA as its data source but differs from the FAA-industry partnership when describing the U.S. piston fleet, counting 172,000 piston-engine aircraft, of which it says the vast majority use leaded fuel. The FAA and industry count 167,000 piston-engine aircraft, with fewer, larger twin-engine cargo and commercial aircraft consuming the most leaded fuel. “Even though it’s a smaller number of the fleet percentage-wise, it’s a larger volume of the actual GA flying in the United States,” Desrosier says. “We’ve always had this 30/70 rule of thumb: 30% of the fleet requires 100-octane or high-performance fuel for high-performance engines and airplanes, but they consume about 70% of the avgas. We recognize we have to have better data than that, and that’s part of what EAGLE is looking at.”
Reid-Hillview Airport facing northwest. A study found that children living east and downwind of the airport had substantially higher blood-lead levels compared to children living west and upwind of the airport. Credit: Santa Clara County
Two weeks after the aviation subcommittee met, the FAA and the EPA, as well as industry, came under fire during a July 28 hearing of the House Oversight and Reform Committee’s Environment Subcommittee. U.S. Rep. Ro Khanna (D-California), the subcommittee chairman, delivered a blistering opening statement. “I’m holding this hearing today because I am outraged that our federal agencies have failed to prevent lead poisoning near small, general aviation airports,” said Khanna. “There are 20,000 such airports across the country, mostly sited in communities of color and low-wealth communities.” The FAA “has chosen a path of delay, holding up the approval of a lead-free alternative fuel for no stated reason,” Khanna charged. “Worse, in similar tactics to those we’ve seen in our committee’s investigation of climate delay and disinformation, the fossil fuel industry and other special interests have also sought to delay the phaseout of leaded aviation fuel.” Among witnesses who testified before the Environment Subcommittee was Santa Clara County Supervisor Cindy Chavez, who described leaded avgas as an environmental justice issue comparable to the crisis over lead contamination of the Flint, Michigan, water supply in 2014-16. “Reid-Hillview Airport in East San Jose is an important example of the environmental injustices posed by leaded aviation gas,” Chavez said. “Reid-Hillview is one of the highest lead-emitting airports in the country [in] one of the most densely populated neighborhoods of any airport in the nation. It’s located in the east side of San Jose, surrounded by over 52,000 people and 13,000 children within 1.5 mi. of the airport.”
A fueling truck at Reid-Hillview Airport delivers Swift UL94 unleaded avgas. Suppliers at Reid-Hillview and San Martin Airports switched to UL94 in January 2022 after county supervisors banned 100LL. Credit: Santa Clara County
Santa Clara County and the state health department sponsored the August 2021 study that precipitated the ban on leaded avgas at Reid-Hillview and San Martin airports. It found elevated blood-lead levels (BLL) in children living in nearby neighborhoods of RHV. Children living east and downwind of the airport had substantially higher BLLs, compared to children living west and upwind of the airport. “Among sampled children [living] less than half a mile from Reid-Hillview, there was an increase in blood-lead levels twice as high as the increase caused by the Flint system failures during the height of the Michigan water crisis,” Chavez said. Companies and groups aligned as the Avgas Coalition argue that ridding 100LL avgas prematurely would ground 30% of the piston-engine fleet and increase the risk of pilots misfuelling airframes that look visually similar but require different types of fuel. There is also suspicion within the GA industry that communities are using leaded avgas as a hook to close some airports altogether. In addition to banning sales of 100LL, Santa Clara County Supervisors have voted to close RHV when federal funds expire in 2031, but earlier if allowed. The board voted in 2018 to stop accepting federal grants for the airport. After an outcry by GA associations, the FAA in December 2021 served notice that it was launching a Part 13 “informal investigation” of violations of grant assurances at RHV and E16. “At both airports, until the federal government certifies the use of unleaded fuel in all aircraft, the county may not ban or phase out leaded fuel or take any actions related to fuel that would conflict with or undermine federal law and airport access consistent with the grant assurances,” the agency stated in a letter signed by Mark McClardy, director of the FAA Western-Pacific Region Airports Division.
Former FAA Administrator Steve Dickson (front row, fourth from left) and association executives unveiled the EAGLE program at the GAMA annual media briefing in February 2022. Credit: Bill Carey
McClardy’s notice also alleged that the county planned to allow the leases of some FBOs at RHV to expire after 2021 and offer only short-term leases to four other tenants. The FAA and Santa Clara County reported no new developments with the investigation. “We have no new information about the ongoing process with the FAA,” Deputy County Executive Sylvia Gallegos said in response to an inquiry to the county. “We are, however, very encouraged by our experience thus far with the implementation of unleaded avgas at our county airports since Jan. 1. At Reid-Hillview Airport, our 2022 operations from January to June are slightly higher than those in January to June of 2021. We have had no fuel-related incidents nor emergency requests for leaded fuel.”
Dating to 1939 and county-owned since 1961, Reid-Hillview has parallel runways (13L/31R and 13R/31L) extending 3,100 ft. in length. According to the FAA, the towered airport has 124 based aircraft and averages 573 operations per day. The agency classifies RHV as a reliever airport for San Jose International Airport. “We’re very concerned about losing airports,” Mark Baker, president and CEO of the Aircraft Owners and Pilots Association (AOPA), told reporters during an EAGLE briefing in March. “Some [communities], notably a couple in California, seem to be using this as an urgency to close their airports, not related to the fuel issue. Those airports have been there for 50-60 years. We have committed publicly as an industry to move away from this fuel by 2030, but it is a point of contention at a few airports.” On Jan. 12 this year, the EPA announced that it will evaluate whether emissions from piston-engine aircraft using leaded fuel endanger public health, a prelude to requiring new fuel performance standards under the Clean Air Act dating to 1970. The agency plans to issue a proposed endangerment finding for public review in October and take final action in 2023. Environmental groups have long lobbied the EPA to address aviation lead emissions. Friends of the Earth petitioned the agency to find that lead emissions from GA aircraft endanger public health in 2006 during the Bush administration, a request the EPA denied in 2012 during the Obama administration. Explaining the denial, the agency said it needed up to three years to develop and publish a proposed endangerment finding based on modeling and monitoring data, to analyze the extensive public comments it expected, and issue a final determination. In the 2006 petition, Friends of the Earth noted that the NASCAR racing organization, prodded by the EPA, had committed to phasing out leaded fuel in stock cars in the next two years. “EPA’s concern with removing lead from NASCAR fuel indicates the importance of removing mobile-source lead emissions, and yet EPA has not acted to address lead fuel use in general aviation fuel,” Friends of the Earth said. “Now that leaded gasoline use in NASCAR has been addressed, it is time for the EPA to focus on the more important task of removing lead from general aviation fuel.” In 2015, the EPA denied another petition by Friends of the Earth, Physicians for Social Responsibility and Oregon Aviation Watch to reconsider its 2012 decision. At that time, the agency said it would issue a final endangerment finding in 2018. In January 2022, in response to a petition by environmental groups including Alaska Community Action on Toxics, EPA Administrator Michael Regan committed to the current 2022-2023 timeframe for an endangerment finding. “The EPA has conducted extensive data collection and analysis to use in evaluating the endangerment finding,” the agency stated, when asked to explain the timeline. “In 2016 the EPA had initiated the endangerment finding action, and it was subsequently placed in a long-term agenda.” Early Candidate Fuels Industry and the FAA have planned for more than a decade to expedite the use of unleaded aviation fuel. The FAA assembled an Unleaded Avgas Transition Aviation Rulemaking Committee in 2011 that issued recommendations in January 2012. In 2013-14, the FAA formed the Piston Aviation Fuel Initiative (PAFI) a government-funded testing program to assess an unleaded avgas “with the least impact on the existing piston-engine aircraft fleet.” The ongoing PAFI effort and broader EAGLE initiative are complementary, the parties say. After conducting a screening information request for proposals, the FAA selected four unleaded fuels for first-phase testing under the PAFI evaluation—two from Swift Fuels and one each from Shell and Total—but ultimately none of the candidate fuels met the program’s criteria. Two of the fuels from Shell and Swift advanced to further testing, but Shell eventually suspended work under PAFI and Swift withdrew from the program. The PAFI effort has been restructured; it now requires pre-screening of fuels and is open to all candidates. Currently, two fuels are being tested, according to GAMA’s Desrosiers: one from a consortium of Phillips 66 and Afton Chemical; the other from VP Racing Fuels and chemical company Lyondellbasell. Data generated through the process would support an FAA fleet authorization if a fuel is tested and found to be acceptable for some portion of the piston fleet, Desrosier says, as well as an ASTM product specification, which supports the production, distribution and commercialization of a product. Separate of the PAFI program, Swift Fuels of West Lafayette, Indiana, and Alda, Oklahoma-based General Aviation Modifications Inc. (GAMI) are advancing unleaded avgas products through FAA supplemental type certification (STC) processes. Executives of the companies testified during the House Environment Subcommittee hearing. Swift Fuels CEO Chris D’Acosta said his company has worked for over two years to develop an unleaded avgas that could be used across the U.S. piston fleet. “That product will be a 100-motor-octane fuel with a 10% renewable component; it will be clean-burning and cost-effective for the U.S. fleet,” he told lawmakers. Compared to the EAGLE program’s 2030 goal of delivering unleaded avgas, Swift believes it will obtain fleetwide certification and industry endorsement of its 100R 100-octane unleaded avgas within three years and be able to introduce it at specific airports by 2023, D’Acosta said. D’Acosta noted that Swift Fuels is the “chief architect and the sole provider” of UL94 unleaded avgas, a lower-octane, FAA-approved fuel that Reid-Hillview and other airports have used to replace 100LL avgas. On July 26, the University of North Dakota Aerospace Sciences college announced an agreement with Swift to supply UL94 for its 100-aircraft flight school. The FAA’s EAGLE initiative is considering making UL94 more available nationwide during the transition to unleaded avgas GAMI started work on its G100UL unleaded avgas in 2009 and years later passed on joining the industry-government PAFI program. Having the new fuel approved by the FAA to run in piston-engine aircraft has been “an exercise in enormous frustration,” the company’s engineering director George Braly told the environment subcommittee. “However, after over 12 years of effort, enormous amounts of certification activity involving over 100 senior-level FAA engineers and managers, last March the Wichita aircraft certification regional office sent us an email saying we had completed all of the regulatory requirements to authorize the issuance of FAA Approved Model List supplemental type certificates that cover all of the spark-ignition piston engines in the FAA’s database,” he added. “They were simply waiting on permission from [FAA] headquarters to do something really hard—pick up a ballpoint pen and put a signature on a piece of paper,” Braly related. “It’s just amazing the bureaucratic mumbo-jumbo that’s gone on since March 4…If those certificates had been signed in March as the law required them to be signed, I feel fairly confident that by sometime in the month of August or September, there would be railroad cars of high-octane unleaded aviation gasoline in California, going to airports like Reid-Hillview and San Martin and the flight school in Bakersfield.”
Annual consumption of all grades of aviation gasoline used in piston-engine aircraft has declined from 32 thousand barrels per day in 1986 to 12 thousand barrels per day in 2021. The most common type of avgas is 100 Low Lead. Credit: U.S. Energy Information Administration
Desrosier explains that the STC process considers airworthiness requirements of a fuel under the FAA’s Part 23 and 33 certification regulations for airplanes and aircraft engines, respectively. The EAGLE initiative is looking beyond minimum airworthiness standards toward infrastructure and environmental aspects of a new unleaded avgas. “We’re looking [at a fuel] from a viability perspective in the areas of production, distribution, and of broader environmental interests—making sure that if there are new components [in the fuel], what do those components mean from an environmental perspective, from an [Occupational Safety and Health Administration] perspective in terms of materials safety and handling,” Desrosier says. “None of those [factors] are looked at in an FAA STC.” The EAGLE participants, including engine and aircraft manufacturers, fuel suppliers, local and federal government entities, associations and other groups, are also discussing ways to reduce the impact of lead emissions during the transition to a new unleaded fuel, possibly by making more UL94 available, and by conducting a pilot program to study lead emissions dispersion at communities near airports. “There are a lot of airports and communities with a desire to look at opportunities to reduce lead emissions in the near term, so another part of EAGLE is taking a look at how we can help enable and facilitate and support that,” Desrosier says. “One of the most important things we want to do is ensure that general aviation can continue to fly safely in the U.S. infrastructure and we can’t have a patchwork of airports with and without 100 Low Lead. That would create an extremely unsafe environment for general aviation in the United States, so we’re looking at enabling and facilitating a reduction in lead emissions by making UL94 available and helping to find programs and initiatives that help do that while maintaining availability of 100 Low Lead.” The FAA conducts fuel testing at the William J. Hughes Technical Center near Atlantic City, New Jersey. The agency says it “plans to more than double the funding for its efforts to move toward a lead-free aviation future.” The FAA is spending $5 million in that area in the current fiscal year and has budgeted $12 million for 2023. Though EAGLE allows the FAA and industry eight years to phase out leaded avgas, the effort must narrow its focus on unleaded alternatives sooner than that, Desrosier says. “We have five 100-octane candidate fuels that we’re aware of,” including the Swift and GAMI products, Desrosier says. “We need to vet those within the next two years. Are they going to be potentially viable or not? It may take more than two years for a fleetwide authorization, to get the certification approval. But within two years we have to know—are we going down that path or not? Do we have a viable candidate fuel or not? If not, what’s our alternative?”
—Based in Washington, DC, Bill Carey covers avionics, air traffic management and aviation safety for Aviation Week. A former daily newspaper reporter, he has covered the commercial, business and military aviation segments as well as unmanned aircraft systems. Prior to joining Aviation Week in November 2017, he worked for Aviation International News and Avionics and Rotor & Wing magazines.
