AOPA Flags Unleaded Fuel Search As One Of GA’s Largest Issues


Finding a drop-in unleaded replacement for leaded avgas is currently one of the biggest issues facing general aviation, according to experts convened for an Aircraft Owners and Pilots Association (AOPA)-hosted webinar on unleaded fuel for aviation on Wednesday. Hosted by AOPA’s Tom Haines and featuring panelists including General Aviation Manufacturers Association (GAMA) President Pete Bunce, fuel industry expert Paul Millner and AOPA President Mark Baker, the webinar is a follow-up to the recently launched FAA Eliminate Aviation Gasoline Lead Emissions (EAGLE) initiative. As previously reported by AVweb, EAGLE is looking to eliminate the use of leaded aviation fuel by the end of 2030 without adversely affecting the piston fleet.

A 100-octane unleaded aviation fuel approved for fleet-wide use has been a long-running goal for the industry, producing programs like the FAA’s Piston Alternative Fuels Initiative (PAFI) and seeing a number of companies pursing supplemental type certificates (STCs) for unleaded fuels. There have been some breakthroughs, with Oklahoma-based General Aviation Modifications Inc. (GAMI) announcing in July 2021 that it had been awarded a first-of-its-kind STC for its unleaded 100-octane G100, which is currently approved for more than 600 piston aircraft engines. However, the Environmental Protection Agency (EPA) announced last January that it is looking into issuing regulations on lead emissions from piston-engine aircraft, a decision scheduled for final action in 2023, which has created new urgency in the search for an approved fleet-wide 100LL replacement.

“Now, why EAGLE is so important and why Mark and I and all of our industry colleagues are pressing for EAGLE is because with the FAA as our partners in this, they are able to communicate cooperatively with the EPA and say ‘we have a plan’ and there is a stake in the ground of an end-date by which we wouldn’t go any further,” Bunce said during the webinar. “With a stake in the ground, we feel that the EPA will be more receptive to listen to the FAA because they know the FAA and industry are partnering on this.”

Panelists stated that EAGLE would make use of parts of PAFI, particularly testing methodology and lessons learned during the process. Millner noted that unleaded fuels from GAMI and Swift Fuels are looking promising. Bunce cautioned that there are a lot of questions to be answered beyond an STC including ensuring transparency and testing standards, fuel distribution and how to refine the quantities needed for the entire piston fleet.

“Our real intent here is to have a fleet-wide acceptable fuel that’s drop-in because with the scale of economics around most general aviation airports you can’t have three tanks and make your choices,” said Baker. “I also believe there’s a high risk to safety if we don’t have communication about what’s appropriate fuel for your plane.”

Throughout the webinar, panelists emphasized the need for communication and industry-wide partnerships. On that front, AOPA is building an avgas fuel coalition aimed at “steering the GA industry to an unleaded future [and] advocating for a smart and safe transition that works for the entire GA fleet.” The coalition currently includes 100 member organizations.

Video: AOPA
Kate O'Connor
Kate O’Connor works as AVweb's Editor-in-Chief. She is a private pilot, certificated aircraft dispatcher, and graduate of Embry-Riddle Aeronautical University.

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  1. No, it’s not a big concern for most GA. aircraft. Most GA aircraft were not even designed to require 100 Octane. Most GA aircraft were FORCED to accept 100LL and AOPA did nothing to stop it.

    Once again AOPA is pushing an octane and fuel that most GA aircraft do not need.

    • I’m not sure where you get “Most GA aircraft were forced to accept 100LL” from. Those same engines can already legally run on mogas. It’s the availability of such fuels that is the problem.

      • I get that from engine manufacturers. Most GA piston engines were designed in the 50’s and do not require 100 octane fuel.

        We were forced to accept 100LL as a one-size-fits-all. AOPA is again supporting big iron and a “solution” that comes from that.

    • While it’s true that about 70% of the piston fleet does not need 100 octane, it ignores the fact that the remaining 30% consume about 70% of all avgas. Most of the planes that require 100LL are in commercial operation and/or flying long distances. Combined, they burn far more fuel than the rest of the fleet.

      In other words, the planes that don’t need 100-octane gas aren’t buying much of it. So coming up with an unleaded fuel that satisfies most of the fleet won’t actually solve much of the problem.

      And the ‘force’ that made us all use one flavor of gasoline was (wait for it)… economics and capitalism.

      Once airliners dropped piston engines from their fleet the demand for leaded avgas plummeted. It wasn’t cost effective to make purple, green, blue, and red flavors. So blue is all that’s left.

      It’s also not economical to split this market further with two pumps – one for 100LL and another for unleaded. Especially when unleaded fuel sales would be much smaller.

      Sure, we can demand that AOPA and the guvmint give us what we want, market forces be damned. But that would be… socialism! (eek!)

    • Arthur, you do realize that most of the aviation fuel isn’t burned by our 50-year-old Skyhawks, right? It’s burned by *working airplanes*, the vast majority of which need 100 LL or equivalent.
      Most airports will keep but one source of avgas, so a low-octane “solution” for minimal sales volume flat out ain’t happening.
      So this is needed, and quickly. It’s been talked about forever.

  2. My question is, what would be required to get GAMI’s 100UL approved, or even Swift’s fuel (for those that can use the lower-octane fuel) for that matter.

    • I get that from engine manufacturers. Most GA piston engines were designed in the 50’s and do not require 100 octane fuel.

      We were forced to accept 100LL as a one-size-fits-all. AOPA is again supporting big iron and a “solution” that comes from that.

  3. What’s wrong with making 80/87 again to lower lead NOW ?? The climate and lead fanatics might like that for a start ?

    • That, or just removing lead and just have 93UL Avgas? The idea that they will spend tens of millions of dollars on a replacement but can’t afford a 3rd fuel tank at airports is so ludicrous as to be insulting.

      • Problem with that is what about all the planes that need 100 octane? You can’t just lower engine performance to make lower grade of fuel work. High performance singles would have to reduce gross weight to meet certain performance standards. Twin engine planes would end up grounded because their single engine numbers are meager enough now, with lower performing engines single engine performance numbers would be non existent, making those planes illegal to fly pt135. I agree your proposed 93UL would work for most lower performing airplanes. But most of the avgas consumed now is by those minority of high performing engines used in air carrier service. I do believe that using 93 octane non-ethanol auto gas would be a partial solution, problem is the EPA doesn’t either understand or doesn’t care that ethanol cannot be used in airplanes.

        • I don’t want a more expensive drop-in replacement when less expensive fuels have been available for decades. Most GA planes don’t need 100 octane. AOPA no longer serves most of the owners. AOPA has missed helping the bulk of the GA owners all this time and, as we here again, only dines with the big buck influencers.

          • Arthur, aren’t we being a bit harsh?
            “The Aircraft Owners and Pilots Association, a not-for-profit organization dedicated to general aviation, was incorporated on May 15, 1939. From the start, AOPA has fought to protect the freedom to fly while keeping general aviation safe, fun, and affordable.”

  4. RAF, I was actually being kind! APPA used to be all you said back in the 70s when I joined. all sort of niceties an support.

    In the last 25 years though, as we see here, AOPA is working for only the upper echelon and hoping that the crumbs from the table will be sufficient. HOW many decades have we asked for existing (less expensive) alternatives to leaded fuels only to have AOPA tell us the idiocy of “piston GA means one expensive fuel; and be happy with that”.

    Sorry, but AOPA has sat on this fuel issue for 30 years and STILL has not helped the bulk of GA planes that do not need what they propose. It’s a damn shame they no longer are a voice for the the bulk of the fleet.

  5. Regardless what acronym (PAPI / EAGLE) the FAA and all the other alphabet groups use this is all about ‘Airport TAXES’.

    An FBO I worked for operated a large fleet of rotax LSA trainers and wanted to install a 91 non-ethanol 1000 gallon approved fuel dock. We discovered that the project was going to cost near $100,000 for a private use system and very little more if we sold to the public. We requested the permits and everything got weird. After many meetings with the airport board and city counsel the project was abandoned because the fuel would have cost over 25% more then the gas station three miles away. So, we got a little fuel truck and request a highway fuel tax rebate each month. The airport didn’t even have a way to collect airport taxes from us. The airport and city would have made a lot of money if they were not so greedy.

    The 100LL replacement isn’t the challenge, how to get ‘every’ aircraft to only buy airport taxed fuel that’s the 2030 quest. The 70% or whatever of aircraft that use lower octane don’t care whether they are paying highway tax or airport tax. we just want to pay the fairest price. 25 to 50% more for the exact same product is not the fairest price.

  6. I have been waiting since 1985 for this problem to be solved. Can you image that the “stakeholders” need another 8 years to come up with a solution?
    2017 lead emission are here:
    I can only speak to KHWO and surrounding airports. Today it has about 2x the 2017 operations.
    In 2017 KHWO was responsible for about 50% more lead emissions than KRHV, where doctors have reported elevated lead in children comparable to FLINT Michigan levels.
    In the early 90s I was given a hard time for fueling with MOGAS! It complete pain in the ass to work with these folks. They banned washing airplanes with water!! There is a children’s park on the east end of the airport, between 2 runway overruns. The vast majority of operations are flight school ops, most of which could use 94UL, today. I am ashamed of the single fuel BS that has been pushed forever. The FAA should have a low bid process for a single unleaded fuel supplier at every single FAA funded airport. The FAA should use eminent domain to take the needed space, provide minimal tiedown areas and through the fence access. FONGU to local municipalities with gigantic liability and other prohibitive requirements. It can be self serve fuel. The real stakeholders are children.

    • Exactly. People think they have a right to leaded fuel so their engine doesn’t knock. No pun intended, but that wont fly. The kids are the priority. If the industry cant find an alternative, and soon, then there will be no aviation fuel for you. And that is where EPA is headed and long before 2030.

      • Seriously? For the children? Next are high performance engine owners getting compared to Hitler?

        If leaded fuel is really that dangerous, I want my damages from the auto companies and refiners for all the years when there was actually enough of the stuff being burned to matter.

        In the meantime, let’s raise the income tax to 70% for the children!

    • Or, you could simply stop placing children at the ends of runways where they shouldn’t be anyways?

  7. The vast majority of Continental and Lycoming engines have compression ratios of 6.5 – 8.5 to 1. Those are not “high compression” engines and don’t “require” high octane fuel. It is just that pilots have been programmed to use it over many years thinking that if they use less octane the airplane will stop running. Most people think that high octane is better and don’t realize it is just a measure of how much the fuel can be compressed before ignition. If you are using an high octane fuel in a lower compression engine you are just wasting fuel (this also goes for car engines). You end up with more fuel going to the exhaust system and not being fully burned in the cylinder during the power stroke.

  8. >>Finding a drop-in unleaded replacement for leaded avgas is currently one of the biggest issues facing general aviation, according to experts convened for…

    Wait, are you telling me that a bunch of people, brought together to talk about a replacement fuel, decided that finding a replacement fuel was one of our biggest issues? Where’s the “I’m shocked” emoji?

  9. Well, while the FAA has the EAGLE initiative to eliminate lead by 2030. The EPA has authority too and they are also undertaking a study to find it an endangerment which will eliminate leaded fuel by end of 2022. The EPA is going to throw this at the wall and it is going to stick. AOPA and FAA need a more aggressive plan or you may find yourself without fuel. They can and will do it. Pilots do not have a right to leaded fuel at the endangerment of kids. The oil and auto industry lost this fight in the 70s over leaded gas in cars. You will lose it for sure over airplanes.

  10. I think Arthur has a point regarding AOPA. As the latest example, who in their right mind would want to encourage and promote an aviation industry partnership between the EPA and FAA? The AOPA has gone completely mad. We have already seen what the FAA alone has done to red tape the replacement of 100 LL. The Europeans solved this issue years ago without the need of the FAA or EPA.

  11. Engine octane isn’t the only concern. Ried vapor pressure is important too. Considering how much fiddling the EPA has done with mogas vapor pressure to reduce evaporation from auto tanks and the resulting vapor lock problems, I can’t imagine sane people inviting the EPA to the dance.

    In addition, let’s not forget why Congress gave EPA the authority to mandate unleaded mogas: It wasn’t human health, it was the health of catalytic converters, which were mandated for road engines to control CO and NOx emissions. Lead poisons the catalyst. The effect of lead on human health was not the issue. However, many were happy that the public associated lead removal with health concerns, and that is evident here.

    The lead mandate specifically permits leaded fuel in engines without catalytic converters: Aviation, industrial and off-road engines such as auto racing and lawn equipment were part of the exemption. Congress also gave the FAA sole authority over avgas blending. The reason for their inaction is simple: By law they don’t have to unless there is a problem. I agree that getting the lead out reduces sticking valve and lead paint problems in aero engines, but there are solutions.

  12. Just curious, but shouldn’t the first thing we do is put a deadline after which planes requiring 100LL cannot be sold? Wouldn’t that help us get replacements by making it more attractive to manufacturers who wouldn’t have to compete with the old tech?

      • I got upon an excellent solution years ago.

        Develop a series of drop-in compression ignition engines to replace the spark ignition ones. Then, when you’re engine hits tbo, replace it, drain and refill the tanks, voila, no more lead, etc etc. With a little engineering in sure it could be done without a weight penalty. Plus you’d have a turbo which is always good but without the added fuel consumption of gas. AND, jets is available everywhere already.

        OH, sorry, there’s too much red tape for common sense to be applicable.

        • There’s always red tape, and it’s a cost you have to pay whether it’s a lot or a little. I’m trying to work the other side of the equation. If Cirrus and others cannot sell their biggest sellers anymore, then they and others will start looking to make new planes.

          Whoever makes a marketable solution knows that they will not have to compete with the existing products. That decreases the competition, and thus increases the likely reward for success. Buyers will not have an option of a new plane without the unknowns anymore. If you think the best thing in the world is a 550 or 540 you will buy used.

        • There have been a number of compression-ignition (aka “diesel”) aircraft engines brought to market. It takes a LOT more than a “little engineering” (physics is a bigger problem than red tape). To date, they’ve all been heavier than gas engines and cost more. Cessna offered a 182 with a diesel engine – practically no one bought it.

          • This is part of my point. As long as the well known and understood solutions are available, the new solutions are too risky for investors.

  13. So, the EPA will be held off by the “plan” since the AOPA is now partnering with the FAA? Only if they ignore the fact that the FAA will be the senior (read controlling) partner and this is the same FAA that has dithered about this issue for decades (see PAFI).

  14. “Panelists stated that EAGLE would make use of parts of PAFI, particularly testing methodology and lessons learned during the process.”

    What the heck does that mean? As I understand it from listening to George Braly speak several times, the whole reason that GAMI went the STC route was because the PAFI process was utterly broken. It’s telling that every other player that had a serious contender in terms of fuel bailed out of the process as well (Swift and Shell).

    Braly and GAMI have spent something like twelve years developing G100UL and have been through extensive, FAA-supervised testing. What the heck else is the PAFI stuff supposed to add to this?