EAGLE Initiative Shows Measured Progress, Fuel Contenders Say at Oshkosh

With four candidate fuels pursuing fleet authorization, OEMs, distributors, and airports are ready to test them.

The EAGLE Initiative moves forward at a measured pace, according to a panel of constituents that presented an update at the Theater in the Woods on Monday at EAA AirVenture at Oshkosh. 

EAGLE—which stands for Eliminate Aviation Gas Lead Emissions—includes partners from aviation industry associations, the FAA, fuel producers and distributors, airport operators, and local community and environmental experts. With the aim to transition away from leaded avgas—100LL—by 2030, EAGLE has the twin missions of supporting development of replacement fuels and advocating for the continued supply of current fuels until the OEMs, operators, and pilots feel secure in the safety and security of the new fuel source(s).

It’s a tall order. Though four entities reported significant progress with their specific candidate fuel, there are varying degrees of confidence in both the composition and distribution prospects of each one.

The EPA’s Next Step Lies Ahead

And time is of the essence—though it’s not prudent to panic yet, according to leaders like Chris D’Acosta, founder and CEO of Swift Fuels, which is currently working on one candidate fuel. What would trigger that response? The Environmental Protection Agency announced its proposed endangerment finding on leaded avgas last October, and it stands to finalize that this October, on schedule.

What does that mean? It doesn’t mean that leaded avgas will be banned immediately. At the briefing, General Aviation Manufacturers Association (GAMA) president and CEO Pete Bunce outlined the steps that would follow the finding. “The people that have to implement the rules are [at] the FAA,” said Bunce of the next steps following the endangerment finding. “There’s a very structured process.” He estimated that there would be about two or three years to completely field the transition fuel. That’s part of the reasoning behind the 2030 goal EAGLE set, to work through this “very methodical process.”

“We have smart people working in these four companies, and we’re going to have a solution,” said Bunce.

Four Fuels

Representatives from each of the companies or partnerships working on those fuels presented their progress, starting with D’Acosta. 

Swift Fuels

Eight years ago, Swift Fuels began delivering the first batches of its UL94 unleaded avgas, and it can now be found in roughly 81 locations across the U.S. The current fuel serves as a drop-in replacement for 130,000 aircraft on the registry—for which FLYING awarded Swift its 2023 Innovation Award. The success of UL94 sets the stage for its higher octane 100R fuel that will serve the remainder of the GA fleet. Swift followed a dual certification program with UL94, acquiring ASTM acceptance as well as supplemental type certificate approval from the FAA. It is pursuing the same path with 100R.

Swift offers a “forever STC” that covers the UL94 as well as future fuels, along with all of the placarding and any changes in documentation. The underlying goal is to establish a sense of security among those who will put the fuel into their tanks—both at the airport and on the airplane. “The emotional uncertainty at this time is really counterproductive to everybody’s interests,” said D’Acosta.


George Braly of General Aviation Modifications Inc. presented next, reporting on the nearly 14 years since GAMI began development on its unleaded avgas replacement—and culminating with the issuance of its blanket STC for all aircraft powered by spark-ignition engines in September 2022. “GAMI has fixed the problem,” said Braly, summarizing what had been the general feeling at the time of the STC’s debut. GAMI is working with OEMs like Robinson (for rotorcraft implementation) and Cirrus in its SR22T, considered one of the most complex powerplant installations to accept the new fuel. 

While the STC has been available for nearly a year, GAMI is still struggling to supply the fuel to the market. To this end, Braly announced it had partnered with “an extremely large producer of aviation jet fuel,” VTOL, to produce the G100UL in quantity. That Houston-based company has finished its 4 million-gallon tank toward making that happen.

LyondellBassell and VP Racing

Two of the fuel developers are pursuing approvals through the Piston Aviation Fuels Initiative (PAFI), established by Congress to achieve fleet authorization through a collaborative industry-government process. LyondellBassell/VP Racing is the first of these. VP Racing is a Texas-based developer of fuels and additives for the automotive racing industry, and LyondellBassell produces high-octane lead components for automobiles. In his remarks at the briefing, Dan Perot of LyondellBassell admitted the partnership was “relative latecomers to this race,” as it started in 2018 to develop its answer to the high-octane avgas question.

“We chose to stay with the PAFI program despite delays during the COVID period,” said Perot, “because we felt that it provided the best mechanism for us to learn what the industry needed, communicate with the FAA and OEMs, and secondly, and maybe most importantly, it required ASTM certification for the fuel.” 

According to Mark Walls of VP Racing, the partnership’s fuel meets all D910 specs, is of the same density as 100LL, and is poised to be cost-competitive. The company is about to enter “full-scale” testing after preliminary work in Lycoming and other engines. Like other fuels in development, Walls said its avgas is fully compatible with 100LL in case of mixing in aircraft tanks.

Afton Chemical and Phillips 66

The second partnership pursuing PAFI-based authorization is between Afton Chemical, headquartered in Richmond, Virginia, and Phillips 66. The pair are also working on new lubricants to accompany the high-octane unleaded fuels. Enrico Lodrigueza with Phillips 66 updated on its progress, detailing the candidate fuel, which uses manganese—a coenzyme used in the human body to break down carbohydrates and proteins, a transition metal—to replace the tetraethyl lead in 100LL. The fuel has an ASTM specification in place, ASTM 28434, according to Lodrigueza, which is “substantially similar” to the D910 spec for 100LL.

Lodrigueza characterized the manganese-based octane booster in use. “Manganese is not a heavy metal. That’s one major difference…it’s an essential nutrient.” As far as testing, the partnership has had “a lot of vetting” by subject matter experts and is ready to proceed with detonation testing at the Tech Center on a Lycoming engine. As with all of the potential replacement additives, close scrutiny is being placed on what issues may occur with the new element in the fuel, such as spark plug fouling. The lubricants testing will also ensure compatibility with whatever oil is in use, for example.

What’s Next?

Clearly, the four candidate fuels are in different states of availability for testing—some more broadly than others—and both the engine and airframe OEMs are eager to keep going. Bunce summarized the position of the manufacturers. “We have the money, our manufacturers have the money to purchase it, to be able to go and look at that fuel and understand what chemical components are in relation to the spec to be able to run it and to do the type of testing that we feel comfortable that we can put our families into that aircraft employing that fuel. And if we see good or bad, we will share it, as manufacturers, to the FAA., That’s our obligation—but that’s the right thing to do.”


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