Cirrus Service Advisory Cites GAMI G100UL As ‘Unapproved’ For SR Series


In a blow to the General Aviation Modifications Inc.’s (GAMI’s) G100UL unleaded aviation fuel program, Cirrus Aircraft posted Service Advisory SA24-14 Tuesday (June 18). The advisory informs operators of Cirrus SR-series aircraft (SR20, SR22 and SR22T) that the manufacturer “does not approve the use of GAMI G100LL fuel in Cirrus SR Series airplanes. Additionally, Cirrus does not warrant or represent in any way an operator’s use of the GAMI G100UL fuel in Cirrus SR Series airplanes.”

Cirrus further advised operators: “Per Continental and Lycoming, only approved fuels may be used for an engine to be covered by warranty. As the GAMI G100UL fuel is a non-approved fuel per Continental and Lycoming, engines known to have run this fuel may not be covered by the OEM engine warranty. For specific details, please refer to the respective Continental and Lycoming engine warranty documents.”

Those advisories were preceded in the statement by a description of Cirrus’s efforts to promote the development of unleaded aviation fuel that would serve as a drop-in replacement for 100LL. “These efforts include working directly with industry associations and all stakeholders including AOPA, GAMA, the FAA, and the FAA-Industry EAGLE [Eliminate Aviation Gasoline Lead Emissions] program through the PAFI [Piston-Engine Aircraft Fuel Initiative] certification program. As of June 2024, EAGLE is actively pursuing three potentially viable alternatives/replacements for 100LL: GAMI G100UL, LyondellBasell/VP Racing UL100E, and Swift 100R.”

Cirrus described its testing programs with GAMI’s G100UL, citing more than a decade of performance testing on materials compatibility and performance. However, Cirrus wrote, “While some aspects of the initial Cirrus testing of the GAMI G100UL fuel are encouraging, other areas, including materials compatibility, remain inconclusive.”

Controversially, while G100UL has received an FAA Supplemental Type Certificate covering virtually all aircraft piston engines, GAMI has chosen not to participate in the PAFI program to achieve ASTM International approval for its fuel.

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Mark Phelps is a senior editor at AVweb. He is an instrument rated private pilot and former owner of a Grumman American AA1B and a V-tail Bonanza.


      • “As the GAMI G100UL fuel is a non-approved fuel per Continental and Lycoming,”
        Covers a lot more than just Cirrus airplanes.
        Most piston airplanes have either Continental or Lycoming…

    • The bigger story is that AVIC/Cirrus and AVIC/Continental have made no real effort to put their own Jet-fuel piston engine in their own Cirrus airframe. Can anyone explain that? Since there is only one facility on earth producing TEL, the disappearance of 100LL could happen tomorrow given the activism in Europe. The rest of the airframers need to wake up also and approve lower-compression gasoline engines on their TCDS, or Jet-fueled diesels, with modified performance data. Watching the PAFI/government/committee process is well… uh know.

  1. Puts a question mark on using that fuel for pt135 operations. If plane or engine are no longer under warranty, pt91, then it becomes the owners decision.

  2. You would think Cirrus would make the effort to see if the GAMI fuel would be compatible with their planes. This soap opera adventure just gets better and better!

    • Matt, their contention is that since Lycoming and Continental have not approved the fuel in their engines that Cirrus does not approve it in their aircraft. That does not mean that their position might change once the manufacturers approve it. But the item mentions materials compatibility and that is a potential issue.

  3. Sounds like Cirrus has a conflict of interest and only wants EAGLE fuel. Wait till they find out that the GAMI fuel is much better; and that the (eventual) EAGLE fuel might strip paint, rots hoses, etc.

    • This could turn out bad for Cirrus. If the EAGLE fuel leads to warranty problems and Cirrus is the only one without the availability to use GAMI, then the Cirrus planes will get a bad name and lose market share. One should be careful where they hitch up their horses.

  4. It is unclear what Cirrus means by “inconclusive” with regard to materials compatibility. It could mean the tests so far have been insufficient to prove compatibility, or it could be a tactful way of saying that an issue with materials was actually found. GAMI should come back with a public rebuttal and provide details. Otherwise, we are left in the dark. GAMI is under a time pressure. Swift will probably get an STC soon for their fuel (which is incompatible with G100UL). And PAFI has their fuel coming also. If GAMI doesn’t get to market soon, they may lose their window of opportunity. They need to be very aggressive in dispelling concerns about G100UL. I don’t think remaining quiet will work.

    • Logically, it could also imply they don’t want to approve it for whatever reason, but haven’t found the evidence they need to back up their desired outcome. It could also be more benevolent than that.
      Makes me wonder what the situation is with 100UL and the CCP. Perhaps they are trying to figure out the formula, and are hoping to use market pressure to get more info out of GAMI?

      • The bigger story is that AVIC/Cirrus and AVIC/Continental have made no real effort to put their own Jet-fuel piston engine in their own Cirrus airframe. Can anyone explain that? Since there is only one facility on earth producing TEL, the disappearance of 100LL could happen tomorrow given the activism in Europe. The rest of the airframers need to wake up also and approve lower-compression gasoline engines on their TCDS, or Jet-fueled diesels, with modified performance data. Watching the PAFI/government/committee process is well… uh know.

        • There was an attempt to put the SMA diesel in the Cirrus before Continental purchased it. IIRC it didn’t work well due to the added weight.

  5. If Cirrus has evidence of G100UL having incompatibility with an approved materials and fails to report that fact to the FAA, it seems to that if a non-Cirrus aircraft has a problem with those materials due to that incompatibility, Cirrus would have legal liability. Since the possibility has been raised, I think the FAA should investigate as a safety concern.

  6. Do the owners of Cirrus also have financial connections to a competitor of G1000UL? I do not understand why Cirrus would even put out this statement, as they are not manufacturers of the engine. Or do they cover the warranty repairs for the engines?

    And doesn’t an STC mean that the fuel is, in fact, approved? Or does it explicitly have to be approved by the manufacturer?

    And then there are the points already made. (In particular the lack of clarity on the possibility of a corrosive nature to the fuel.) This all seems rather odd.

    • It all goes hand in hand regarding the type certificate-
      The airframe [ produced by Cirus ] mated to the engine produced by Lycoming and Teledyne Continental …
      The engine manufacturers had previously come out with their own statements regarding unleaded fuels at this juncture and I am sure their corporate attorneys jumped on the airframe manufacturer, in this case – Cirus – and had Cirus cut a fast ” Service Advisory ” as well to reduce what is perceived as liability risk with the knowns and unknowns at the present time.
      As stated before, soon the AV Insurance underwriters will be coming forth with their own cautions.
      And price hikes and policy denials IF .. one doesn’t wait and use an ASTM sanctioned FAA approved unleaded..
      It will negate the entire Braly STC method of doing business.

  7. Other than the engine, Cirrus has fuel tanks, hoses, pumps and seals to warranty.

    They should indeed be more transparent.

  8. Without some kind of explicit liability shielding, all these well publicized disputes seem fodder for schools of liability sharks in any mishap where it can’t be proven that the aircraft never ran any of these fuels…and the insurance industry will also have their say…somehow don’t think it will result in lower premiums.

  9. At the present time without further clarifications on numerous bullet points here mentioned ; no one knows for certain what ” materials incompatibilities ” really means that Cirrus is exactly mentioning and referring to.

    For all anyone knows; Piper, Cessna, Beechcraft, etc. could all soon release their own ” Service Advisories ” stating not to use Braly G100UL fuel.
    This is all playing out just as the FAA molded and crafted it – with a “maybe 2030 ” ASTM only approved unleaded av fuel.

    And with that ASTM sanctioned fuel will be behind it a European style price per gallon.
    Outfits such as the LyondellBasell/VP Racing UL100E venture that is going the route of the ASTM sanctioning has the high end corporate structure, financing, political power, and other influencers to get their juice to home plate and blessed by the FAA and engine and aircraft manufacturers all in a hell of a lot easier and faster fashion than less influential fuel manufacturers.

    And what about AOPA’s ” Baron Testor ” trials ?
    I haven’t been following that closely as of recent.

    Cirrus’s Service Advisories on Gami G100UL has to surely affect that soon to be Mark Baker report..

  10. IMO, this whole mess is Continental and Lycoming’s fault. They should have switched to materials that are compatible with unleaded fuel at least 20 years ago, long after the automotive industry paved the way. But it seems they’re STILL building engines that require fuel from 50 years ago! Disgraceful.

    • You’re just kidding, right? If not, did you actually think about what you wrote before you wrote it, and re-read it before you posted it!! Seriously?!

    • Certified engine manufacturers just don’t “switch materials on certified engines. Certified airframe manufacturers cannot just start installing “better” experimental engines on their planes. It’s not their fault for following regulations.

    • FYI: Lycoming switched to hardened valve seats in the 80s. Continental, on the other hand, only did so a few years ago, so there are many noncompatible engines out there.

    • This is likely more than just valve seats. It appears GAMI’s fuel composition is different than most current formulations (including automotive gas). Think about seals, gaskets,etc. How does one change it to be compatible with every possible chemical that might be used 20 years down the road?

    • It’s the FAA first and last. Continental did give us the 550 series as well as bought out and still sells two diesel solutions. Lycoming has been undoing some innovations for experimental aircraft.
      Still, you cannot blame them too much for not innovating in a business where new models of certified planes are rare which is primarily the FAA with a lot of from other government institutions, the tort bar, and the plane manufacturers.

  11. This whole debacle makes me think GAMI is like the guy who invented the intermittent windshield wiper that the auto companies tried to screw over.

    As another poster pointed out, the 2030 “deadline” is suspiciously close to when GAMI’s patent will run out. Then EAGLE can announce that G100UL is fully approved but no one will have to pay a license.

  12. Why don’t they amend the TCDS to restrict Cirruses to 100LL only?

    And how long is the Lycoming warranty? As short as they can get away with!

  13. Cirrus is a China owned company. All you Biden supporters out in California soon won’t have any fuel for your planes. What a bummer…

    • I live in California and am definitely not a Biden supporter. No one in this part of the state is.

      ANYWAY…. If Continental and Lycoming have not approved this fuel and will deny warranty claims on their engines if the fuel is used then I don’t see the fuel as very useful at all.

    • And the Chinese send thousands of students to the US for flight school training every year. They’re not exactly our allies and many complaints have been made about training them. Someone wants to sow seeds of doubt into any unleaded fuel. The $80M+ that Innospec makes on TEL each year is, in their opinion, worth fighting for.

  14. Well, I can see why the person who has to honor the warranty on a million dollar airplane would be hesitant. Basically you can still do what you want, just don’t expect Cirrus to do a warranty top overhaul….

  15. Cirrus seems to have forgotten which company is responsible for the existence of their turbo models. Tornado Alley and GAMI are the same company.

    If I were George I’d probably cease all work involving Cirrus.

      GAMI has led the way in research on compatible fuels.
      They spent their own money to develop it.

      They presented it to the FAA, which approved the fuel for ALL piston-engine aircraft.

      The “Johnny-come-lately” types have tried to derail it by branding it as “Non-ASTI approved”–but ASTI hasn’t approved ANY replacement fuel–I don’t believe they have the expertise to certify fuel.

      The aviation media hasn’t done a good job of explaining that GAMI IS THE ONLY APPROVED ALTERNATIVE FUEL to be available and approved for ANY 100 OCTANE PISTON AIRCRAFT in the event that 100LL is banned.

      This is “regulation by innuendo” (“A problem MIGHT happen–even though none have turned up to date, and it has been approved by the FAA. It will be interesting to see how this plays out at OSHKOSH–where aircraft owners may have direct access to the fuel developers, the regulatory agencies, and airframers.

      As for me, this “CYA” statement by Cirrus has lost any respect I may have had for them. In the meantime, I’m waiting for AvWeb to cover the OTHER side of the story.

  16. I think many are reading too much into this service advisory, this is a lawyer written CYA statement of the obvious. Cirrus is not going to be on the hook for any engine related warranty claims associated with using an STCed fuel. The STC applies to the aircraft, which gives Continental and Lycoming an out on their warranty because the aircraft has been modified from the original TC configuration. Try telling a customer who dropped $750K on his shiny new airplane the engine warranty has been voided because he used an FAA approved fuel.

    Until Congress passes a law approving the UL alternatives as legal equivalents to 100LL/130 AVGAS and absolving the airframe and engine manufacturers of liability for use (plus FBOs/ distributors), a complete changeover will never happen. It’s the society we have created where the lawyers will sue you out of business, and businesses have to defend themselves accordingly.

    • >>The STC applies to the aircraft, which gives Continental and Lycoming an out

      Not exactly. When you buy “the STC” for your airplane, you actually get two STC’s. There’s one STC that applies to your airplane (airframe) and one STC that applies to your engine.

      Continental and Lycoming don’t have an out. There is an approved STC that directly applies to their products.

      Now, whether any manufacturer can deny warranty when an operator has properly used an approved STC, that’s a question for the lawyers to answer, I suppose.

  17. First, as a Cirrus owner for about 20 years I do not trust the current management. Just look at the way they treat their captured audience regarding parachute upgrade cost (to those who do not know – they keep coming with so called “upgrades” accompanied with huge price hikes, for no other reason than because owners have no other choice.)

    So I would start by looking for a back-channel by which Cirrus can make money by dissing GAMI.

    However, I see no other choice than a legislative action which will release manufacturers from liability – VERY strictly – due to use of unleaded aviation fuel, and in return fuel cost control. That said, I would like to see a comprehensive scientific research showing unequivocally the connection between GA and lead in the vicinity of airports. My understanding is that several multi-year tests failed to show that.

  18. The EPA and current administration has to be putting tremendous pressure on FAA to cram out unleaded fuels, even if the long term consequences on engines or systems isn’t clear, they don’t care.

    These are the same people waging war on fossil fuels and who are trying to ban gas and diesel cars and trucks, they are zealots and our little airplanes are collateral damage in their climate crusade to save the planet.

    If we don’t start voting in sane politicians and reining in the vast administrative state you better be ready to take the train, because that’s when they will stop.

      • Not many run nowadays. People need to stop buying the lies and demagoguery and simply vote out all incumbents until they feel the country is headed in the right direction.
        Game theory would tell people to stop voting for the least worst candidates and leave the line blank (or vote neither if your state does that). Unfortunately, the vast majority simply cannot grasp that level of game theory.

          • You do realize most people’s votes simply do not count, right? So it’s mostly just sending a message. If you want to tell BOTH parties their candidates are unacceptable, then reject both of their candidates.

            Right now, the combination of gerrymandering and nose holding is telling the winners they are acceptable when they are not. And, it’s telling the losers they just need to get out more of the base.
            Imagine instead of the independents and moderates holding their noses and it comes out 53 to 42 percent, those same people vote for neither and it comes out 48 to 37. That’s just 1 in 10 voters on each side saying, “neither”. If you combine that with more people rightly rejecting incumbents who do not get results, it would change everything very quickly. It could overcome most gerrymandering making it a bad strategy. The incentives we have right now are why we have the results we have. Our clowns aren’t just born, we make them.

    • “These are the same people waging war on fossil fuels and who are trying to ban gas and diesel cars and trucks, they are zealots and our little airplanes are collateral damage in their climate crusade to save the planet.” -Tom Newman

      These ARE the sane politicians, and the sooner the rest of us pull our heads out of the sand and recognize that serious change has to happen mighty quick if we want to preserve a livable planet, the better our chances of pulling it off. Those of us in the industrialized West are entirely too dependent on cheap transportation to support our luxurious lifestyle. This has to stop, and we need to adapt to locally self sufficient economies and less consumtive

      • (Accidental premature post.)
        …less consumptive lifestyles. Aviation is entirely too wasteful and carbon generating to be part of the solution, and the new crop of EVSTOLS are not going to replace 747 freighters anytime soon. Railroads are electrifiable and way more efficient, and there are plenty of abandoned lines out there, now serving as rail trails that could be relaid with rails to produce a denser transportation network. But the bottom line is, we’ve got to wean ourselves from transportation dependency and learn to live locally. We’re already seeing ominous changes in our local climate, happening ominously fast. As a former aviator with some schooling in climatology, I think we’re way behind the eight ball in this

        • Gee, you think the FAA has anything to do with this? If aviation had come anywhere close to keeping up with auto innovation, we’d be very efficient today. If we could get half our airports back, most trips would beat using an economy car by now.
          You put any reasonably equivalent tax level you want based on pollution and get government to get out of the effing way, and flying will be big again in a decade.
          Of course, that’s never going to happen because the reality is no one in government makes the environment an actual priority. The environmentalists simply use their cause like a cudgel to justify more redistribution policies while actually sacrificing the environment.

    • I’m sure they are aware of it. Please read the details in the service bulletin Cirrus put out and Lycoming’s SI. G100UL is unique and as you pointed out, not listed in Lycoming’s bulletin. Materials compatibility is a big part of the fuel issue.

  19. It all comes down to liability. The 1,300,000 liability attorneys we have in America are a testament to the sheer size of a monster industry whose “take” from judgements is growing by some 16% every year, far above the inflation rate. Particularly in an industry like aviation manufacture where risk is concentrated in a relatively few products, not only is the direct cost a huge factor but the ever-present specter of some mammoth judgement distorts every business decision.

  20. Someone please correct me if I’m wrong, but didn’t GAMI develop this fuel completely independently of the manufacturers? Given that, and GAMI’s refusal to submit to ASTM and insistence on keeping the formulation secret, I’m surprised that it has taken this long for the manufacturers to push back. No doubt that development of the fuel is a great step forward, but GAMI’s ‘just trust us’ approach leaves them open to just this sort of response by those with warranty and certification responsibility.

        • lol, yeah. Do you see now how it’s irritating when people give ridiculously unconstructive comments and then end them with an ironic and snarky…

          …have a nice day?

          • Sorry, old Eric – I meant, can you please elaborate on your comment that I should consider myself corrected? Did GAMI get support from the manufacturers (my comment seeking correction)? If so, could you provide details?

            I’ll try in the future to make sure that my comments are on-topic and informative (though I don’t think I’ve transgressed in that way in the past). Clearly, I’ve put a burr under your blanket, though I don’t know why. Too bad this forum doesn’t allow for DMs so that you can give me your criticisms in private rather than making public attacks! As ever, feel free to ignore my comments whenever you want to!

            Thanks, and have a great day!

    • Definitely the needle on the barber pole, JA : “GAMI’s refusal to submit to ASTM and insistence on keeping the formulation secret, I’m surprised that it has taken this long for the manufacturers to push back. No doubt that development of the fuel is a great step forward, but GAMI’s ‘just trust us’ approach leaves them open to just this sort of response by those with warranty and certification responsibility.”

    • Braly filed a bunch of patents. Don’t they explain what’s in the fuel? And doesn’t the FAA-required testing to get the STC include materials compatibility? I think he even used a Cirrus as the test platform for a bunch of the work.

      • Hi, DaDaDan! The patent (as I saw it in Google’s patent search engine) describes the additive in only general terms. Patents can be granted that shield trade secrets, and it appears from reporting that I’ve seen that GAMI’s intent is to keep their formulation proprietary and license companies to manufacture the additive.

        Paul Bertorelli reported in 2022 that all research occurred in GAMI’s engine test cell, and if the engine or airframe manufacturers were involved, they’ve been quiet about claiming credit for their part. Lycoming and Continental were uninterested or hostile and Cessna non-committal, though (ironically) Cirrus did help out somewhat. Clearly, though, they’ve changed their tune somewhat.

        As I understand it, the STC process requires conformance with certification standards. I’m not properly versed in what that requires with respect to a fuel; maybe someone else here who’s still following this story can better inform us all.

        Have a great day!

  21. Lawyers;
    Fear of frivolous but expensive litigation.
    The fuel is approved; full stop.
    One doubts that anyone at Cirrus has any clue about fuels or chemistry, or combustion.
    Perhaps they wanted GAMI to give them a blanket STC and Braly said not unless you pay.
    Engines do not need lead, they need octane.
    People do not need lead; it is bad for them; get over it.
    This whole dragged out shemozzle is embarrassing to a supposedly high tech industry!

  22. One thing not to forget here in this discussion. an STC is a major alteration to the type design. Any non-manufacturer approved modification (STC) to any aircraft would likely void its warranty, regardless of it being fuel, fairings, navigation equipment,etc.

      • Not sure why this is a problem unique to STCs. If PAFI blesses a fuel, Cirrus could put out a statement just like this one too.

  23. Cirrus Aircraft may nullify warranties for aircraft that use unleaded General Aviation Modifications Inc. G100UL fuel, the world’s largest piston aircraft manufacturer said in a service advisory published June 19.

    The announcement is a setback for GAMI, which has spent years developing an unleaded, high-octane fuel to replace leaded avgas in the worldwide fleet of piston airplanes.

    Cirrus has tested G100UL in its SR20, SR22, and SR22T aircraft, and the company said it finds some aspects of the new fuel “encouraging,” but critical safety questions regarding materials compatibility remain “inconclusive.”

    “Cirrus does not approve the use of GAMI G100UL fuel in SR Series airplanes,” the company said in its advisory. “Cirrus does not warrant or represent in any way an operator’s use of GAMI G100UL in SR Series airplanes.”

    G100UL is made from a different chemical composition than leaded avgas. Any avgas replacement must be compatible with existing aircraft fuel tanks, bladders, lines, and accessories in addition to performing well in engines.

    The FAA has approved supplemental type certificates for GAMI G100UL covering the full spectrum of piston aircraft engines. G100UL hasn’t been part of the FAA’s ongoing, multiyear Piston Aviation Fuel Initiative process known as PAFI, however, and it hasn’t been evaluated under American Society of Testing and Materials (ASTM) standards.

    About 2,500 Cirrus aircraft are covered by standard three-year and extended five-year warranties. According to the terms of those warranties, they become void if “products . . . not supported or approved by Cirrus are installed on or applied to the aircraft.”

    Cirrus SR22, SR22T, and some SR20 models are equipped with Continental engines. Continental warranties exclude damage that results from the use of “non-approved fuel.”

    Some SR20s are equipped with Lycoming engines, and Lycoming’s warranty also excludes damage from “non-approved fuels.”

    Neither Continental nor Lycoming has specifically approved G100UL.

    The aviation industry is seeking to move away from leaded avgas as soon as a safe alternative is certified by the FAA and widely available. The FAA Reauthorization Act of 2024 requires airports that offered avgas in 2022 to continue to do so until 2030 or until an FAA-certified alternative is available.

    GAMI, a privately owned firm based in Ada, Oklahoma, has performed extensive fuel tests in its own engine lab and ongoing materials analysis using many types of commonly used fuel tanks, fuel lines, and sealants.

    AOPA has logged about 180 flight hours in a Beechcraft Baron using G100UL in the left engine and avgas in the right. The 1966 Baron’s newly overhauled Continental IO-520 engines are being regularly inspected and their data is recorded and closely monitored.

    AOPA intends to fly the Baron with other unleaded fuels when they become available.

    Cirrus says it’s been collaborating with several unleaded fuel manufacturers including GAMI, Swift, and LyondellBasell to find a safe alternative to leaded avgas.

    “Safety is our upmost core value,” the company said. “We will not approve the use of a fuel until we have completed thorough and comprehensive materials and flight testing.”

    AOPA Publications staff

  24. If it is correct that Lycoming and Continental have not approved the fuel, then Cirrus could not legally appove it if they wanted to, unless they got an STC on the engine, which would be unusual. The airframer is required to comply with engine limitations, whether they be contained in the engine TCDS or engine Installation Manual. Fuel type and grade is an engine limitation.

  25. This is a definite negative for anybody considering buying a Cirrus aircraft product. Cirrus should have made an effort to make all available unleaded avgas useable in there aircraft if they are serious about staying in the piston Aviation market.

  26. This is all Fun and Games until the SCOTUS rules this week that the EPA has overstepped their bounds and that the recent rules are all negated.

  27. Support DeltaHawk and their development of larger engines. They should be the OEM standard.

  28. Grab your popcorn and make plans to attend Oshkosh. I’m sure there will be a lot of talk and presentations about the current state of unleaded fuels from all sides.

    As for the Cirrus statement that testing of materials compatibility remains inconclusive, probably means testing of fuel tanks and plumbing leading to the engines and not the engines themselves. Their vague response could well mean that they haven’t found any specific problems, but are still testing.