FAA Studying Unleaded Avgas Transition


The FAA has at least temporarily stopped its investigation into whether Santa Clara County in California is violating its grants agreement by refusing to sell leaded gasoline at county-owned Reid Hillview and San Martin Airport. In exchange, the county has agreed to consider taking part in a study into the transition process from leaded to unleaded fuels at airports across the country. The agency has agreed to stop its investigation until at least next August while Santa Clara officials mull over the FAA’s invitation.

They seem to be leaning toward being part of the study, however. “When the county banned the sale of leaded aviation gas at our airports, we did so to protect the health of those who live in our community, especially children, who have been unjustly exposed to harmful pollution for decades,” said County Supervisor Cindy Chavez, who represents the area surrounding Reid-Hillview Airport. “We would welcome the opportunity to showcase what we have done here in Santa Clara County, which can and should be replicated across the country.”

The airports only sell Swift Fuels 94UL because of a study the county commissioned that revealed slightly higher than average lead levels in children who live near the airport. The airports have received millions of dollars in FAA grants over the years and one of the stipulations of receiving the money is to provide the services and facilities necessary for safe aircraft operation.

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. There is a potentially huge problem brewing in the great Avgas UL world. GAMI fuel cannot be used in certified aircraft without buying GAMI’s STC as they have elected not to seek ASTM standards certification, even though they say they meet key aspects of it. This will require owner/operators to buy an expensive STC which is, in essence a license to buy their fuel. GAMI, in cooperation with AVFuel as a distributer, points out that it will be the only game in town for airports using AVFuel as a supplier.

    In its Q&A 17, GAMI states, “The STC pricing will be based on engines and horsepower, in a manner similar to the pricing for other fuel STCs that have been available for low octane gasolines.” and Q&A 2, “Current best estimates are that G100UL avgas will cost
    60-85 cents/gallon more than 100LL as the fuel leaves the producer’s facility and begins to enter the stream of commerce. ” Q&A39, “Because avgas volumes are low relative to jet fuel, and because airport fuel storage tanks have become very expensive to construct and maintain, it is unlikely that any given airport FBO will have multiple unleaded fuels for sale.”

    In its other Q&A comments, GAMI says it meets ASTM D910 (100LL) for detonation and D909 for full take off power (equiv to 115/145 Avgas), yet in Q30 asking about ASTM certification GAMI states, “No. GAMI elected to use the existing and approved STC
    pathway to obtain approval for our general aviation aircraft and engines to use G100UL avgas”

    So, while the bulk of GAMI’s revenue will come from fuel sales profit and will far exceed the $450-$500 STC hit per engine, per airframe this cost is not trivial, especially for a C152 operator and is concern if you don’t have it and need fuel at an FBO that only has the GAMI on field.

    Years ago, I bought the Peterson STC for MOGAS at a cost of $1/hp and the EAA’s was just becoming available when 80 went away. GAMI (per the ever pervasive hangar talk rumors) wants double that for its STC.

    SwiftFuels to its credit markets its 94UL which meets the old ASTM D910/D910-95A used for 80 octane fuels used in the low compression O-470-R engines and many others. According to an airport I frequent which has SwiftFuel 94UL I am good to go without an STC because of that spec. If I want, I can buy a forever STC from Swift for about $100, but apparently don’t need it to use 94UL in my airframe engine combination.

    If GAMI’s fuel is universal as they say it is, why to we need to pay them for the STC/license to buy its fuel at likely a $1-2/gallon more than 100LL and double or triple the cost of Mogas for those of us who can and do use it and can get it?

    The FAA should insist on having manufacturers that meet ASTM standards, get their fuels qualified and permit all airframe/engines that qualify to use their fuels.

    GAMI’s take if the entire GA fleet needs an STC to get the only fuel available: 150,000 GA aircraft burning gasoline x $450/GAMI STC x 70% of the fleet = ~ $50M and likely more when twins and engine replacements are needed. GAMI’s web site is very quiet on the cost of the STC per airframe/engine combination. GAMI’s competition, if/when it arrives will face a very high barrier even if it does not require an STC, or alternatively we will have to buy the Mogas STC, the GAMI STC, the Swift STC, the UGuess(n..) STC to insure we can legally buy the fuel that will be available on our next stop or restrict ourselves to airports that carry the fuel we have a license to buy. There has to be a better solution that this.

    I cannot see how this is a good solution to our fuel issues.

    • Swift 94UL meets the ASTM D910 specification because it is essentially 100LL without the octane-boosting lead additive. To expect a novel high-octane fuel of different chemistry to meet the D910 specification is not logical. To expect an industry consensus organization that includes competitors to cooperate in establishing a commercial specification for it ignores a obvious conflict of interest.

      GAMI developed its own production QC specification which is FAA approved (D910 is not, it’s a commercial consensus spec). Had GAMI gone the PAFI/EAGLE path we would still be waiting for a viable UL avgas solution and then as ASTM spec/blessing. I applaud their political courage and grit for spending over a decade of time and their own money to bring a solution to market. I cannot criticize them for their fee for FAA-required compliance with the STC. It seems in line with precedent and provides the beginnings of a ROI for their investment.

      • Hello Jonathan!

        Please allow me to suggest some corrections for some of your points.

        First, American Society for Testing and Materials (ASTM) is far more than just a, “…commercial consensus spec” provider. ASTM is an example of the institutionalization of American scientific standards that distinguishes us from countries like China. Perhaps if you actually read one of these “specs” you would realize that they are far more than just some commercial consensus.

        Second, if you are going to pick a specification to read, may I suggest you go with ASTM D910-20. You will find that it very specifically provides “build standards” for LEADED avgas – specifically, 100LL.

        Third, Swift Fuels UL94 is an unleaded avgas using the “build standard” ASTM D7547-Grade UL94, not ASTM D910. It is an unleaded avgas of 94 aviation octane (as distinguished from automotive which is an average of RON and MON). Aircraft engines requiring 100 octane for safe operation should not use UL94.

        Finally, the most significant point I can offer you here is that there is no ASTM standard (yet) for 100 octane unleaded avgas. ASTM 7719 is a purchasing (only) specification for 100 octane unleaded avgas, not a build standard.

        I totally agree with the main thrust of your comments about GAMI’s STC. Essentially, G100UL that you will be able to put in your airplane soon was completely developed – finished – by 2013. The time between then and whenever it is actually being pumped has been consumed by politics and redundant, combative FAA demands for testing. Most of the tests were done more than once. GAMI has earned the right to recover some of their investment by charging for their STC.

    • If “GAMI’s web site is very quiet on the cost of the STC per airframe/engine combination.” why are we complaining about it?

      Let’s say it is $1 a horsepower? That is the same cost of 30 USG of AvGas. So, less than one tank. I’d pay that.

      One needs to ask themselves, “How much would you pay to potentially double your TBO?” Because that is the question to ask. Removing lead from our fuel could very well lead to doubling the TBO of our engines, and that is something we will know for certain once we start flying our planes on UL fuel.

      • If anyone is actually curious about the GAMI STC pricing you can enter you engine and airframe information, including serial numbers and get the price for the two STCs (engine and airframe). If not, please write a short essay explaining why whining about a one-time buy-in to support the only organization to have actually developed a lead-free fuel that works for all avgas fueled engines is helpful. Nobody is making you buy it.

        I personally would like to be able to visit RHV again and buy gas. I’d also like to not have lead sludge pooling in the engine and be able to use a synthetic oil with longer service intervals as modern automobiles do. I pay more for a set of fine-wire spark plugs to mitigate the lead fouling than the price of the one-time STC for G100UL that would eliminate fouling. I’d like to have this transition to unleaded fuel happen during my lifetime. Get a grip.

        • I agree. We had to switch to fine-wire plugs in one of our club planes because for whatever reason it was particularly prone to lead fouling (neither of the other two planes were). The plugs we’re using also have a shorter lifespan, so I’d estimate over a year or maybe two, we would have already broken even–if not gotten ahead–on the cost of the STC. And that’s not even taking into account longer oil-change intervals that would be possible with an unleaded fuel.

          As soon as there is availability of G100UL in my local area (“local” meaning, within ~150-200nm), I expect my club will purchase the STC for all three planes.

  2. While the FAA already took way to long to certify an unleaded alternative because of their goldielocks approach to the topic, they shouldn’t have allowed that county to ban 100LL while no suitable alternative is available.
    This to me is a very cowardly decision by the FAA, whou should have voided the county decision not to allow 100LL sales on the spot.

    • The dirty little secret is that “government” has elevated poor decisions to an art form. Most of us have come to expect “government” to make decisions based on the wrong reasons.

      “Safe and Effective”….

  3. It is indeed extremely disappointing that the FAA has allowed this 100LL prohibition to occur as it discriminates against those whose aircraft requires 100LL.

    A couple of important points: The MOU between FAA/Santa Clara County pauses the Part 13 informal investigation, but does not affect the process of the Part 16 formal investigation. The County now has to formally respond to the FAA in the Part 16 complaint. https://www.regulations.gov/docket/FAA-2022-1385/document

  4. Why is the FAA just now initiating studies regarding avgas Pb issues. Has this not been on the table for about two decades? It would seem logical that if such actions are to be taken such as banning Pb in avgas, there should be a sound scientific basis including exposure dose response issues, not whether there might be a minuscule amount in the environment from who knows what origin. And please no hysterical knee jerk comments about how bad Pb is since it is totally dose response related and the potential dose from avgas exhaust does not even register.

    • I would say that looking in to possible health-related risks of using leaded avgas ignores the bigger issue: lead is actually quite bad for our engines, other than the octane boost it provides to the few engines that actually require the higher octane.

      • While I fear the ‘health hazards’ of the trivial amount of lead our humble little airplanes contribute not at all I agree our motors ARE indeed better off without it. This fact ameliorates part of the increased cost of the UL fuels.

        • My little plane is FINE without 100 octane and without lead. Just stop putting in the lead in the current AvGas and I’m fine.

          As for everyone who bought planes that actually NEED 100 octane, well, you’ll need to work out your own complex and expensive alternative to what everyone knew was coming.

  5. The GAMI STC Site is stc.G100UL.com. You need engine and airframe model and serial numbers to get the pricing from the automated STC sales site. It costs nothing to look so you can think it over with actual information for your situation.

  6. The GAMI STC will undoubtedly be reasonably priced, otherwise there will be a large contingent on the low end of the market who will simply ignore it. Vendors want to sell the product, not act as STC-checkers.

  7. UL 94 is the real answer to the unleaded, aviation fuel problem. All new manufactured aircraft should be made to use this fuel.

    • That’s all well and good for new aircraft (and the folks that can afford one), but what about the rest of us with a not-new aircraft and their engines? Even for those engines that don’t require 100-octane, they’re certified to use only 100-octane, absent an STC or blanket ruling by the FAA.

  8. In response to Craig and others, GAMI is not the only company to develop a universal unleaded avgas. They have just “introduced” their product sooner by using an abbreviated testing and STC process. Swift Fuels has been developing their unleaded 100 octane “drop in” fuel for years, and has committed to availability in 2023. In addition, they have refining capability and distribution capability, which GAMI is still working on. And they have claimed their fuel formula is less expensive to produce than GAMI’s.. That might help explain why refiners and the government are waiting for Swift to complete their thorough testing protocols and promised ASTM approvals before rushing to produce GAMI’s fuel. The FAA’s decision to stand down on pressuring Santa Clara County and Reid Hillview Airport to resume offering 100LL until at least August is a clue that they expect unleaded fuel from one or both developers to be on at least some airports this summer. And it should be noted that Swift has had the production, rail transport and distribution infrastructure for delivering UL94 to northern California airports in place for more than 2 years…

    • Is it true that Swift’s new fuel won’t work on the high compression engines? I heard it’s only around 97 octane and all the Cirrus, late Bonanzas, and 210s won’t be able to use it. If so, who cares?

  9. Eric F.

    Agree with UL 94 FWIW. I’ve been using UL94 for years. I have to travel 40 miles to get it. Great stuff in my 160hp Lylclone.
    OTOH, I can burn 100 LL and do as it’s the only avgas available on my field. The cheap FBO won’t install a second tank and pump for UL 94. Not that it would do any good. There’s a shortage of UL 94 due, I suspect, due to tank cars and trucks hauling it to KRHV.
    Nothing but fouled plugs in my 150hp Lycoming when using 100LL. I had to switch to mogas for that engine. Had to haul it in 5 Gal containers. Cross country trips were almost impossible.
    My C-85 doesn’t care what I burn. 6.3:1 compression ratio will do that for you. Lead does build up on the valve stems though.

  10. Art W. writes: “GAMI says it meets ASTM D910 (100LL) for detonation and D909 for full take off power (equiv to 115/145 Avgas), yet in Q30 asking about ASTM certification GAMI states, “No. GAMI elected to use the existing and approved STC
    pathway to obtain approval for our general aviation aircraft and engines to use G100UL avgas.”
    The FAA can be good at dragging issues out. Failure to give them something to lean on, like compliance data in the form of ASTM consensus standards, ensures it will drag forever. GAMI argued the ASTM standard was flawed and that their findings were more acccurate. Maybe so, maybe not. But the FAA is anything but dumb, and just because an applicant says it’s so, doesn’t mean it is.