An FAA Q&A statement issued today (June 19) leaves little room for ambiguity when it comes to the mandate to keep 100LL fuel available, nationwide, regardless of efforts to ban its sale in favor of existing unleaded options. The statement cites Grant Assurance 40 (Access to Leaded Aviation Gasoline) established by Section 770 of last year’s Reauthorization legislation.
According to the Q&A summary, “Grant Assurance 40 prohibits airports from restricting 100LL availability until an alternative fuel meets the established criteria. Most importantly, the Q&A document explains that no unleaded fuel currently meets the criteria as established in Section 770.”
The curt answer to Question 4 (Do any of the high-octane unleaded fuels meet the criteria in Section 770?) leaves little doubt. “No. As of April 2025, there is no fuel that meets the criteria of 47107(22)(B)(i) and (ii). For example, a fuel would have to be authorized for all aircraft and no fuel has been authorized for the rotorcraft fleet. The FAA will provide additional information when the criteria is met.”
As for the teeth to enforce the mandate, the Q&A document adds, “In order to maintain Airport Compliance Program integrity, FAA personnel may participate in limited oversight to detect recurring deficiencies, system weaknesses, or prohibited actions by sponsors.” It also notes that Congress included a civil penalty option available in the case of any alleged violation investigation.
Aren’t grant assurances the way they kept Mayor Daley from destroying Meigs Field and the meatheads in Santa Monica from shortening the runway, et al ??
Grant assurances are as good as the guarantee that Neville Chamberlain got in 1938.
Meigs wasn’t protected because it didn’t have any grants, i.e., no grant assurances.
So here we are with the FAA and AOPA promoting and forcing the dangerous 100LL fuel on the aviation community. There should have been efforts by at least the AOPA to promote fuels like UL91 or UL94 which can be used by over 60% of all planes without an STC and almost all the rest can be modified to use it with an intake air intercooler or water injection. By continuing to promote 100LL they continue to promote the dangers that come with its continued use such as exhaust valve damage caused by lead deposits, spark, plug fouling, due to lead deposits and higher TBO‘s caused by lead accumulation in the oil sump. Nobody can even use modern synthetic oils because of the lead in the fuel contaminating the oil which results in oil changes twice as often as should be needed. Currently the AOPA is putting more money into attorneys to keep 100 LL on the market and practically none into promoting alternatives to enhance the safety of Aviation. There may never be a suitable UL100 available, but there are other solutions that can be pursued now.
Before too many people pile onto Ehsif727’s comment above, I’d like to set the record straight and remove any ambiguity about AOPA’s position on 100LL:
In summary, AOPA is 100% committed to helping us get to an unleaded alternative to 100LL and will push hard with the FAA and Congress to help get us there as quickly as we possibly can! While we do this, we also want to ensure that pilots aren’t taking on unknown risks in the process. I personally fly a SeaRey with a Rotax engine and I work very hard not to burn 100LL in it because everything works so much better on 94UL or equivalent automotive fuel. We just need a similar option for higher horsepower engines as quickly as we can get there. We’re very close with the 3 candidate fuels and I think we should all lean in to help at least one, or all three, be successful in the market. The future of piston powered aircraft depends on this.
Darren
President and CEO, AOPA
AOPA might be betting on a horse that will never cross the finish line. Every engine can be converted to run on UL94 but for some reason AOPA keeps promoting the lie that it is not possible. When 115 octane fuel was not available anymore they modified those engines to use the 100 LL with an STC’s.
I still remember going to airshows 25 years ago when the AOPA would say it’s just a couple of years off and we will have UL100 trust us.
It never happened and I’m not trusting you now to get across the finish line cause your track record is terrible.
AOPA is like Thanos and Elizabeth Holmes they just keep telling everybody there is a product and with just a little more time it will happen.
Ehsif, I wonder what your position might be if the FAA told you that you had to modify your engine in order to use some new fuel they had developed. Telling me that I have to do so sounds a little like Marie Antoinette telling the French peasants to “eat cake”. When I bought my plane (before George Braley or the FAA got serious about unleaded fuels), I accepted the fact that the only fuel available for it was 100LL. I didn’t like the leaded fuel, but I wanted the performance because it matched the cross-country missions I had in mind. But telling me that I have to spend thousands of dollars installing some water injection system in order to run on 94 UL, or accept a significant derating of performance, is ridiculous - especially since GAMI HAS developed a fuel that runs fine in my engine. According to friends with similar planes who have run G100UL, it runs fine and has produced zero problems with either the engine or the fuel system. As usual, the FAA has stuck itself right in the middle of this whole mess. They were the ones that approved G100UL for ALL spark ignited aircraft engines, but now they are standing squarely in the way of GAMI being able to market that fuel to the public. The right way to move forward is to enable all airports to offer both fuels and let the public decide. So, tell the distributors in California that refuse to transport G100UL that they cannot refuse to do so, or they risk losing their license to carry either one. But stating that G100UL is not approved is saying their own decision to approve it through the STC process was not valid. The FAA has mishandled the whole unleaded fuels initiative from the get-go, and now they are just making things worse, instead of trying to fix it.
Things change in aviation like transponders became a requirement and then ADSB and we made those modifications. I didn’t know when I bought the airplane that I would have to be doing these expensive things and adding extra weight to my airplane, but I did it because things change and you have to adapt.
I think you already know that if you added water injection even while using a low octane fuel your power would actually increase.
It seems that all the people with these high-powered airplanes wants to push their new expensive fuel to be the only fuel available even though 2/3 of the piston aircraft fleet doesn’t need it and will incur no benefit when using it. I feel it is unfair to that group for you to insist that the only pathway to an unleaded fuel is 100 octane..
We’ve heard the stats on minority of GA fleet that must burn 100LL is the majority consumer of avgas. Does AOPA know the percentage of its membership that own acft that must burn 100LL?
AOPA advocacy would be helpful in pushing for multiple grade availability at FBOs…states that don’t support alcohol free gas availability could be reminded of the immediate tradeoff resulting in less lead emissions.
Economics also matters to the majority “low end GA” fleet that doesn’t require 100LL. I understand the need not to throw the 100LL users “under the bus”, but would prefer to not find myself “under the bus” if 100LL replacement requires airframes changes (as implied in a recent AOPA article) and higher cost fuel; especially when there is a cheaper lower octane solution with many fleet hours on it already.
Doesn’t help when FBOs resist the cost of duplicate infrastructure (multiple grade fuel), but have the funds to install eVTOL chargers as part of a PR campaign…and then apparently jack up the price of 100LL to pay for the charger.
It does not matter what FAA, AOPA, PAFI, or anyone else considers an “approved” or “compliant” fuel unless the engine manufacturers accept the product and revise relevant documentation to reflect such acceptance.
Exactly. Flying any of the soup might be approved and fine with anyone. What matters is that engine manufacturers approve the fuel and provide warranty. All else will cause massive constipation.
Not that engine manufacturers didn’t know about the “neckbreaking speed” of TEL disappearing from fuels, or where blindsided by rapid regulatory developments, which (by the way) occured nearly 40 years ago. Highly negligent, to let everything come down to the wire before acting.
Neither the constant bickering and arguing about the need for TEL or its microscopic presence in a niche market fuel will help alleviate the issue.
If it weren’t so sad, I’d be chuckling. The thing that gets me is everyone is so concerned about multiple fuels. Funny, back when dinosaurs roamed the earth, and I got my private, just about every airport had both 100 and 80’octane pumps. Now wer’re concerned they we might need ‘duplicate’ distribution systems?
The smart operators kept those extra pumps. Over the years they’ve been used for mogas (well until the avgas distributors insisted they stop or they wouldn’t deliver 100LL. )One local field still has theirs, and sells 94UL from it.
As one poster noted above, we’re throwing money at eVTOL charging stations. Well, we may just have to throw some money at extra tanks and pumps, and adopt a two fuel solution.
Ironically, the STC process can be a hindrance as well as part of the solution. In my case, I have an AA-5 with the STC’d high compression pistons. The STC clearly requires 100LL. It was done before 94UL was even a thought. The same piston configuration is ok’d for other airframes to use 94UL. But, the STC holder will never change the STC. So I’m stuck with 100LL, though I’d gladly use 94UL if I could. This is why a drop
In replacement will be needed
What you are not explaining is that engines can be modified require retarding of timing which reduces horsepower. OK for airshow warbirds which are over powered. Not good for us 100 octane civil aircraft who would have to reduce our gross weight and thus payload to meet performance requirements like IFR departure climbs. Nor are you mentioning that while the majority of aircraft can burn 94UL the majority of flight time (70% in fact) is performed by aircraft requiring 100LL. In other words, the 100 octane aircraft are the ones “carrying the mail”.
The solution has been staring us in the face for a half century and it is called mogas. The world’s largest producer of aircraft engines, Rotax, designs all its motors to run best on ethanol-free, lead-free gasoline, aka mogas. What cars for the past 30+ years needed anything other than gasoline or diesel?
Problay many aircraft owners pump in the 100LL when they would rather pump in a 100 octane unleaded aviation certified fuel.Maybe the fuel supplier could install a separate canister for lead,and a fuel nozzle with a gizmo that could be set to dispense 100 no lead,or 100LL Avgas
Mogas without ethanol is at best, 90 octane. Rotax has not been able to get beyond 150 hp. You’re not going to run a 6 place single on 150 hp. Even Rotax knows the limitations of its technology. Otherwise they would be building 300 hp aviation engines.
Why isn’t AOPA or any of the other organizations, including the environmentalalists, leading a charge as part of “aggressively pursuing alternatives” to get an exception for aircraft from the mandates that require ethanol to be included in mogas?
I live in CA and my home airport has multiple tanks and pumps where RIGHT NOW airport management would happily dispense both 100LL and ethanol free mogas if they could get the ethanol free mogas.
My understanding is distributors mix in the ethanol when filling the delivery trucks and could supply fuel without ethanol if not mandated to include it.
The old saw about not letting perfection be the nemesis of progress certainly applies here. By all means you should be working to get a 100 no-lead fuel designed and approved so nobody is left behind, but that shouldn’t prevent you from also educating and working to remove barriers that are preventing mogas from being pumped by those airports that could offer both.
It’s actually 160 hp, for the Rotax 916 iS. They have a six-cylinder under development which will probably exceed 200 hp. The point is, all new manufacturers of aircraft engines design them to run on mogas or Jet-A (diesel). We should be looking forwards, not backwards.
Thanks to Darren for his statement. I also appreciate his reference to Rotax engines. Many of us fly aircraft with those engines, yet it’s the first time I recall seeing any mention of them in all the AvWeb discourse on unleaded fuels. Like many Rotax owners, to take care of my engine I have to carry auto gas in gas cans to fuel my airplane. I would have loved to have seen access to unleaded fuel (either auto gas or 94UL) required in grant assurances by last year’s Reauthorization legislation. But there seems to be almost no thought being given to the continued costs imposed on aircraft owners by forcing them to use a fuel that they do not need and that is harmful to the life of their engines.
Where did the 70% statistic come from?
"While airplanes with lower compression engines make up 70 percent of the GA piston fleet, they only burn about 30 percent of the 100LL. Higher compression engines use 70 percent of the 100LL supply. "
IOW the high compression engines are burning most the fuel and doing most the traveling. Time to stop talking about “Rotax” and this or that bug smasher. People like me who typically fly 500-700nm missions for business are the real users. When you think about it, it makes sense.
So where did AOPA come up with this? Yes Twins burn almost twice as much as single engine aircraft. But piston twins are a dwindling market and can be replaced with Jet A burning substitutes. Larger piston singles have to make up the difference. Take out Cirruses used in primary training and then what do you have? Probably an amount close to or less than the so-called “bug smashers”.
I knew you would question the number because it does not comport to your narrative, and that is all you got, a narrative.
Another way of looking at that statistic that never gets talked about is 70% of aircraft operators have been paying higher fuel and engine maintenance costs for 40 years to support the flying done by the other 30 percent. I think it’s more fair to say that each aircraft flying segment has been carrying the other’s mail.
This isn’t that different from the sun setting of 80 octane. That required new engines on the Cessna 150 ( to become the Lycoming powered 152) and the 172 ( the much maligned N-model). If 100LL goes away, Beech, and Cirrus will adapt ( if they think there’s still money in GA) and buyers can choose that solution or they can take their turn in the same barrel the “bug smashers” were in for 40 years.
Operators like Cape Air, who still flies Cessna 402’s because there is nothing currently available to replace it, probably burn more 100LL in one day than most weekend flyers burn in a month. When my home airport had to replace both 80 and 100LL octane tanks due to EPA mandates in 1989, the owner had to make a choice. He couldn’t afford to spend over $100,000.00 each for two new tanks, so since the oil companies were in the process of dropping 80 octane the choice of fuel to sell was made. I just purchased an older plane which has an engine the was designed to burn 80 octane fuel, not the 100LL that is sold now. I purchased an auto fuel STC since in my home area there are several gas stations that sell ethanol free auto gas that is 90 octane. I’m sure most small airports that have just one fuel storage tank that is used for 100LL are going to continue to sell 100 unleaded once it is available. The volumes in avgas sales just cannot justify the cost of a second dispensing system just for a lower grade of avgas.
I do feel that the FAA should stop any further certifications or approvals for engines that require 100LL. Same with airframe type certifications. Have to start somewhere. If the FAA keeps approving airplanes that run on 100LL then the longer it will take for the unleaded option to be available.
I get the gist of your comments, Matt.
Just for accuracy and to clear up any confusion, Cape Air does also operate some other aircraft (which probably also require 100LL with, I think GTO-520 Lycoming variants) such as Tecnam P2012, for example.
100 LL has approximately 2x the lead of leaded auto gas.
Lead is a continuing serious environmental and human poison.Nascar banned it after elevated lead level in team member blood was found within the racing community. I worked in a gas station as a kid in the 1970s and the occasional kick back of leaded gas which was still for sale , caused significant health issues in my hands for years to follow. the use of lead in fuel has shown to have lead to many societal problems for a very long period of time. for reference pleas read the attached AND it you question the summary of the document refer to the PEER REVIEWed scientific papers referenced in the foot notes..Tetraethyllead - Wikipedia
While scientific data and information on the effects of lead is plentiful, we are dealing with an industry, which has categorically rejected the idea of progress in terms of aviation piston engines for nearly 8 decades. Just picture an (any, really!) engine requiring an engine oil change every 25 to 50 hours in todays day and age. This is INSANE!
I remember working in the automotive industry in the US in the early 2004-2005 time and vividly recall that I was in shock, when learning that Americans were told to change their oil and filter every 3000-5000 miles. Like clockwork, we changed hundreds of gallons of motoroil per week, despite the fact that modern automotive engines run 20-30.000 miles with the same spec oil in Europe.
AVGAS is finished from every viewpoint. Its future use is incomprehensible from every angle.
Users want a drop-in replacement, preferrably equally priced or (better yet) cheaper. 25h and 50h oil changes no longer cost $10 nor can we excuse changing expensive oil filters every few weeks. Things are getting expensive and with our current path and quality of leadership, that trend will continue.
The time for round-table meetings and a targeted campaign between stake-holders, users, distributors and developers, engine and aircraft manufacturers was 30 years ago.
From history we know that humans are their own worst enemy when money, power, prestige or greed are involved. We know that entire empires have sunk this way. Yet, we are able to think about occupying Mars and we send rockets into orbit on tourism missions, but we cannot, for the life of us, get this issue solved.
Maybe 10 generations from now people will dig up old Cessna’s and Cirruses and discover which type of advanced electronic devices are screwed into the panel, but then ask: “What where they thinking?!” when the old firebreathing Lycoming or Conti Engine is dug out…
agreed . the reason for the use of the engines was to NOT have a PSRU or liquid cooling. these were maintenance headaches in WW2 aircraft BUT the saving grace there was the extremely short life of fighter aircraft engines. Ross gaurentedd 100 hrs for the merlin this increased to 200 hrs. the big radius ran far longer. This drove th adoption of big slow air-cooled aircraft engines. HOWever ROtax has show unevivicolly that a PSRU with high revving engine can very effectively replace the Lycoming Continental standard. HOWEVER knew they cost more. they also wear very little with the TBO driven by the multi piece crank design. (though a zero time crank and rod assy is MUCH MUCH less expensive that a similar Lycon.