100LL Replacement Talks Held-Issues Remain


The developer of the only available unleaded replacement for 100LL says he met with an industry committee charged with smoothing the transition to an unleaded future for the first time last week. George Braly, whose G100UL is available by STC for all gasoline aircraft piston engines, said he met with members of the Eliminate Aviation Gasoline Lead Emissions (EAGLE) task force, which was formed 18 months ago. He told AVweb at a forum held Monday at AirVenture 2023 on the unleaded fuel situation that he offered solutions to issues raised about the accessibility of G100UL, especially for non-certified aircraft.

Braly and Swift Fuels have chosen the STC route for making the replacement gas legal to use in GA aircraft, while Afton Chemical/Phillips 66 and Lyondell Basell/VP Racing are attempting to get a “fleet authorization” for their fuels through the FAA’s Piston Aviation Fuels Initiative program that will also eventually lead to approval by the standards organization ASTM. EAA Chairman Jack Pelton has repeatedly noted the STC process is unavailable to those who fly experimentals and warbirds because they are uncertified and ineligible for STCs.

Although the unleaded fuel is documented as safe for the engines, builders and restorers must ensure it is safe for the tanks, seals and other parts of the fuel system. Information needed to establish that compatibility is closely held by Braly for G100UL, and Pelton maintains that homebuilders cannot fully determine the suitability of the fuel for their aircraft. The two companies seeking fleet authority have to disclose their formulas to get certification and the data will be publicly available.

Braly said he offered to show the group how that compliance can be achieved by any builder without him releasing trade secrets but they haven’t taken him up on that. He’s also adamant that he will not reveal those secrets because he doesn’t trust the ASTM process or its players. He said his fuel has been widely tested and shown safe and he’s now working on distribution networks to get it to airports. Braly also alleged that some unnamed leaders of aviation groups have actively worked against his effort to get the fuel universally accepted.

EAGLE has set 2030 as the year that leaded avgas is eliminated entirely and committee member Lirio Liu, who heads the FAA’s certification department, said there is a lot riding on getting it done. “[The world] is looking to the U.S. to solve this problem,” she said.

Russ Niles
Russ Niles is Editor-in-Chief of AVweb. He has been a pilot for 30 years and joined AVweb 22 years ago. He and his wife Marni live in southern British Columbia where they also operate a small winery.

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  1. “EAGLE has set 2030 as the year”
    Ya, sure. Unless the one and only producer of TEL suddenly stops producing. Hows-a-bout 2024?

  2. What a waste of time! The money and energy being wasted on tilting at this windmill’s fuel cell is embarrassing at best and criminal at worst! And it won’t even make any discernable difference in the end.

  3. If the owner of the data can make a statement of what materials are compatible w the fuel and provide corresponding data then there should be no issue . That is how 100 ll was approved. The experimenter would then check his bill of materials to this an certificate the fuel system

    For three most part this is academic
    The real issue is an entrepreneur took on big oil and beat them at thier game and no one likes it.

    • What continues to baffle me is how the aviation alphabets that are supposed to be advocating for pilots: a) continue to support the waste-of-money-and-time EAGLE/PAFI process, and b) seem to be working AGAINST G100UL availability.

      It’s no wonder Braly doesn’t trust the ASTM process.

  4. I don’t understand why a home builder can put STC’d avionics or any other electronics he desires in his airplane but he cannot use an STC’d fuel. Makes no sense.

    • For one, the avionics in experimentals aren’t “STC’d” to those aircraft and don’t need to be under the regulations as written. Specific components may be eligible for installation in certified aircraft under applicable STC’s, but that has little to do with installing those components in an experimental. In short, the Supplemental Type Certificate approach can’t (legally) apply to an experimental because there is no Type Certification to Supplement. For another, the experimenter can use whatever fuel they like. Unfortunately, though, when there are compatibility details withheld (whether by the fuel producer, materials provider, or someone else), there is no way for the individual experimenter to know what combinations of fuels and materials will and won’t work other than by trial and error that may be expensive, dangerous, or both.

      In my opinion, this is one big, nasty example of what happens when a government attempts to exert complete control by attempting to write regulations for all eventualities, only to be reminded that there will always be something they didn’t anticipate because bureaucracies never adapt as fast as reality.

    • Because when you get to the pump, it will ask you for the number of your STC. Since you don’t have an STC, you can’t enter the number.

      Simple as that.

  5. Why us Jack Pelton trying to stop implementation of Unleaded 100?
    Something wrong here!
    The airplanes are “Experimental”!
    They can use any fuel the builder decides to use; period.

    • Yes on an Experimental you can use any fuel you want to. The problem is that you won’t know what damage the fuel can do to your fuel system. Would you want to be flying around in a plane that the fuel tanks start leaking at 5 gal a min. because the fuel dissolved the sealant in your tank or swelled up the fuel line going to the engine so its too lean to produce the power you need to get over the tree at the end of the runway.
      Experimental’s are not built to “STANDARDS” like production aircraft. You as the builder can use what ever you want in the fuel system when building it, so that’s why there is no STC for them.

      • “Braly said he offered to show the group how that compliance can be achieved by any builder without him releasing trade secrets but they haven’t taken him up on that.”

        To me, that sure sounds like EAA is actively working against allowing the use of G100UL. Are we really saying that experimental builders are looking up the MSDS of every component and fluid used in the construction of the aircraft? And if they are, that they even understand how all of the components interact with each other from a chemical perspective?

        In any case, it’s not like leaded 100LL fuel is benign to fuel components anyway. It’s just that 100LL is an historic fuel that also happens to be the only universally available fuel. I doubt 100LL would even be able to gain approval today if the situation was flipped and we were going from unleaded to leaded fuel.

        • We don’t even need 100 octane. 94UL would be fine for almost all of us, and with slightly different heads (and yes, a few percent less power) it would work for the rest also.
          All of this is to protect certificated airplanes, whose documentation would need to be re-done (at enormous cost) if they lost several percent of engine power (and that’s what we’re talking about – several percent, plus the cost of changing the cylinder heads).

          • Right, and that is a big reason why we do need 100 octane. Most airports can’t afford to have multiple fuel types, and if the situation is bad now with GA airports under attack, it will be even worse if some airports will no longer be viable for the aircraft that do require 100-octane fuel.

            The only reason some airports have 100LL and JetA is because most of the JetA consumers are turbine-powered aircraft that consume rather large quantities of JetA.

          • Ah, the mob rule mentality. Even when you try to disguise it, it’s still nasty smelling.
            When the high performance planes become useless, the value of the entire fleet of remaining planes likely will not go up. More airports will close, or raise prices to compensate for lost business.
            SEL turbine owners will be the only winners (for a short time).
            I wish you guys would stop acting like this is some sort of survival raft game and quit trying to vote the high performance guys off the boat.
            You’d think the existing problems which are obviously caused by small numbers of piston owners already would have educated you.

  6. It’s never, ever about the technology, it’s always about the money. The large fuel producers sat back for years stalling on the FAA mandate to remove tetraethyl lead from 100LL and until they can piggyback on the $$$$$, time and technology that Gami spent to produce this fuel we aren’t going to see it available at the airports. Lead fouled spark plugs, valves and cylinders in my aircraft engine which runs perfectly on zero lead 91 octane pump gas is an afront to common sense. “Fuel leaking at 5 GPH hitting trees at the end of a runway”? Lions and Tigers, Oh my! The RV-12 that I built to ASTM standards has run fine for 5 years and has had zero tank leaks and no issues with unleaded 91 octane pump gas. But when I need to refuel on a cross country there’s that big white 100LL tank at $6/gal. You would have thought that even Mogas would be available at most airports, nope. Only saw it once at KLHM in NorCal. 100UL will be available overnight once the large fuel producers get to “dip their beaks”.

    • In fairness, the manufacturers of my (composite) airplane have prohibited the use of pump gas with ethanol in it – which is all pump gas, in my state. That’s because it tends to separate when it sits, and the ethanol goes to the bottom, where (at high concentration) it gradually dissolves the epoxy. That, in turn, leads to fuel contaminants that block the fuel filter, leading to fuel starvation, long before it causes a leak in the tank.

  7. I love the conspiracy flinging about “big oil” while simultaneously rooting for a company who will have an absolute monopoly on unleaded fuel. It *is* all about money, and making as much of it as possible for GAMI.

    He says his fuel is totally safe, and he has the data to prove it but won’t show it to us? Sounds exactly like a certain submarine maker.

    We Americans love the underdog, but granting the underdog an unlimited license to print money under any circumstances it dictates for the foreseeable future is not the solution. EAGLE is doing work we should all be supporting.

    • I’ll be the first to rally against businesses for abusing their power, but clearly none of the “big oil” businesses have been able to come up with an aviation-suitable 100-octane unleaded fuel in the decades since automotive fuel had its lead removed. They simply haven’t put in the time or money to develop such a fuel, whereas GAMI clearly has. They used their own time and money to develop and test G100UL, so it seems reasonable that they should be able to gain some financial benefit from their work.

      But on the subject of monopolies, let’s not forget that there is only a single vendor of TEL. Maintaining the status quo isn’t exactly going to help us either.

    • GAMI will have to partner with refiners who will by necessity want to see data. Also, presumably, the FAA has seen evidence of its safety. That’s what the STC process was for. You’re being unfair as your standard isn’t forced on all sorts of other companies.

      Since there’s a monopoly on TEL, we could, theoretically, get GAMI to partner with more than one refiner such that we replace the TEL monopoly company with the GAMI monopoly company. Just a thought.

      As I was reminded by an earlier comment, this problem is only a problem because piston aviation has been destroyed by government policies. We are here because we’ve become a tiny minority. Lots of FBO’s used to have multiple pumps. For all the money being spent fighting, the FAA could likely fund self serve second pumps for a few hundred airports as a pilot program and get started.

  8. Chris D’Acosta, Swift Fuels CEO, will discuss current and future Swift Fuels plans for the transition to an unleaded fuel for piston aircraft. Chris will share what’s happening with their high-octane 100R unleaded avgas product and their premium UL94 unleaded avgas.

    To view further details and registration information for this webinar, click here:


    The sponsor for this seminar is: FAASTeam