The quest for an unleaded replacement fuel for 100LL looks like it will be a winner-takes-all affair between the three candidate fuels still in the running. Although much has been said about collaboration and cooperation in the quest to get lead out of aviation gasoline, the three proponents have now all said they’re not interested in having their fuels mixed with those of the other two companies because of liability concerns. All three companies have said their fuel can be mixed with 100LL.
In his forum at EAA AirVenture Tuesday, Swift Fuels CEO Chris d’Acosta reiterated his intention to make company’s 100R the only option for unleaded avgas and to get it in general distribution before the 2030 deadline set by the FAA and EPA to phase out 100LL. D’Acosta has specifically rejected the commingling of his company’s fuel with GAMI’s G100UL because of its use of aromatic amines as an octane booster. D’Acosta did not mention the potential to mix his fuel with LyondellBasell’s E100, which, like Swift, uses a chemical called ETBE to raise the octane in its fuel.
LyondellBasell spokesman Dan Porreau told those attending his company’s forum on Wednesday that liability concerns mean his company will not pursue commingling its fuel with the other two, although he did say that he expected “one or two” fuels to make it through all the approvals.
LyondellBasell is the only fuel going through the FAA-directed PAFI process and getting an ASTM International specification which, assuming all the testing is successful, will lead to “fleet authorization” of its fuel by the FAA. He said the fuel has been submitted for its third attempt to get the ASTM approval and he expects it to make it through in the next few weeks. Testing of the fuel at the FAA lab in New Jersey is less than half complete and will take another couple of years. He’s expecting fleet authorization in 2027 followed by a staged rollout of North American distribution before 2030. The fuel will be produced at four refineries in the continental U.S. and one each in Alaska, Canada and Mexico.
Porreau also reiterated that there is no “drop-in replacement” for 100LL possible and that some aircraft will need modifications to use any of the unleaded candidates. Many of those will be in the form of “paper modifications” in which the operating parameters of the engines will be set to reflect the ability of the fuel to perform in varying conditions. Some will require mechanical modifications, which will also affect performance.
They are trying to prepare many of us that we will have to accept limitations on our engines. Not gonna work.
The way this is going is FAA will just approve fuels, with limitations if necessary.
The life of 100LL will be extended.
Courts will get involved.
Then the marketplace will resolve the issue. Will FBOs choose the little guy or big guys? The big FBOs will choose where their money is. Those who can might carry two alternatives.
The small airports will choose what their fleets use. People might have to rebase their planes. One will have to search for airports that carry fuel they can use. A mess.
Good question, but it’s quite clear that the FAA favors the big guys.
I sense some lawsuits in the future, none of which will be helpful for GA or the phase-out of 100LL.
Ethanol-free Mogas remains the best fuel moving forward. It already could fuel 80% of the existing fleet of piston aircraft and is the primary fuel for the world’s largest maker of aircraft engines, Rotax. Jet-A and Diesel will also play an increasing role as more affordable diesels emerge.
Great, now that my big bore Bonanza can keep flying with new ruddervators, the un-leaded fuel in the future will probably make my brand new engine obsolete…..makes G100UL look pretty good right now!
The “as more affordable diesels emerge” was supposed to happen a decade ago. Instead, even Diamond was forced to offer some traditionally-powered aircraft. I just don’t see all of the big bore piston-powered aircraft switching to diesel, so that leaves turbine conversions as the only real option.
Very good point. Turbine fuel burn though is too high for light aircraft flying at low altitude. There are several new smaller diesels coming out of Italy, stay tuned.
Can we just go back to two grades of Fuel?
All these crazy expensive fuels coming to us in the future for the 2/3 that don’t even need it seem like a crazy idea. UL91 is now commonly found in other countries. Why does the US have to be a lager?
Lead needs to be replaced with either copper or iron or some combination for exhaust valve cooling. As long as all the fuel developers and the FAA refuse to divulge what their fuel attitives are, no replacement will happen because no one knows what is being proposed. And the results over at least 2000 hours of engine operations; which no one is talking about. So far, this topic appears very brain dead without essential 2000 hour testing of the fuel attitive; and without any reporting to the public.
I am glad to see that the other contenders have been diligently working and moving their solutions forward. We have until 2030 to find a replacement and we should use all of the time we have available to fully develop and vet the replacement that every one of us will eventually be forced to adopt.
I am very curious to learn the pro’s and con’s between aromatics and ETBE being used as the means of obtaining the required octane. Good or bad, we all understand what TEL does in our engines. I have no understanding thus far what we should expect with these two new different types of additives. With 100LL, if I get a fouled plug, I know how to recognize it and what to do about it. Will there be new/different considerations to be aware of with the alternative formulations? I have to assume yes, but I have no idea what they might be at this point.
I am glad to see that all of the shrieking voices demanding that we have to adopt the first suitor willing to take us to the prom or else the world will end have quieted down somewhat. I have no dog in this fight, but decisions made in a rush or a panic usually turn out wrong.
agree with @gmbfly98. I’ve been following the diesel quandary since Zoche first started talking about it. Now two engine overhauls since and a third at 700 past TBO and still strong, I looked at the SMA, Theilert, and now watching the DeltaHawk closely. The French engine had a service ceiling limitation of 12000 ft, which is not enough to cross the Rockies, even in the lowest passes, and cost more than the airplane. You can buy a lot of gas for the $125k I was quoted then. Especially if you are burning mogas which I have ever since 80 went away. So, if you can get 230 HP out of an O-470 with less problems on no lead 87Mogas or 91Mogas fuel, why aren’t the airports, especially those who used to carry 100LL, JetA and 80 carrying it? The demand is there as half the GA aircraft at the two airports I’m based are bringing it on the field.
My CHTs are about the same when I use Mogas as with 100LL. I installed the ElectroAir EIS and they rose about 10 degrees but still well below 320 (Cont 0470R) and at cruise with either fuel there was no problem. I borescope at 50 & 100 & annual, and have not seen any significant indications of inadequate valve cooling or overheating. The biggest problem I had with TEL additives is valve sticking back about 30 years ago and of course lower plug fouling no matter what I did until I got the Mogas STC. Can you tell why you think we need to put metal in the fuel and how it cools the valves when the combustion chamber temps/pressures are already cooling after the burn event when the valves are open and the combustion gases are being vented?
I’ve been on of the few public advocates for mogas for the past 20 years, along with my friend, Todd Petersen, former owner of most autogas STCs. You can get Mogas at most GA airports in Europe, alongside 100LL and Jet-A, but not in the US, which is ridiculous. Avgas sellers probably make high margins on 100LL, and most FBOs are clueless when it comes to aviation fuel, follow the advice (and threats) from their Avgas suppliers. See pure-gas.org for thousands of mogas suppliers.
Absolutely. I have the Petersen STC, and my 80 octane engine runs just fine on that and the base stock 94UL that Swift uses. I agree that a substantial part of the problem is certain aviation fuel companies do use deceptive or other coercive means to discourage FBOs from selling mogas. In the 90s/2000s, it was fairly easy to get it on the road with minor off direct routings, but today it’s increasingly rare. I solved part of the problem by installing extended range tanks and tankering fuel. I’m lucky in both of the states I am based, one can buy EtOH free mogas at most pumps, or on the field at one FBO. The other part of the problem is lycoming converted the C152 engines to use 100LL while older engines used 80.
Mogas won’t replace the majority of fuel sold. Looking around at Oshkosh this week, it seemed to me to be a lot more than 20% of airplanes - actually flying - that can’t use 94.
You are 100% correct. But that is not the point. 100LL does not replace the majority of fuel sold, which is Jet-A. But it still needs to be available for the small percentage of piston aircraft that still need it. The vast majority of legacy piston aircraft and virtually all new piston aircraft run just fine on Mogas. The world’s largest producer of aircraft engines, Rotax, designs it engines to run on Mogas. Just as the car makers do. Being dependent on a boutique fuel like 100LL is just bad policy moving forward. GA must leverage volume production in other industries of materials, electronics, engines and fuels in order to lower costs.
The majority of PLANES may be able to use 94, but the majority of 100LL is going into planes that can’t use mogas or 94. Those of us who fly regularly cross-country burn a LOT more fuel than the $100 hamburger crowd.
Ive seen your claim made before, but never with any evidence. Airports however earn much of their revenue from hangar rent and maintenance shop income, so the number of aircraft based at an airport is more important than the fuel they burn. By not offering Mogas, airports ironically encourage aircraft owners to self-fuel. That means also no aviation fuel taxes are collected. In my state of NC, one can submit receipts for mogas purchases for aircraft and get state fuel taxes reimbursed. What is needed is mogas on all airfields along with Avgas. Small selfservice fuel stations do not cost much. I used to sell them…
Think it through. What engines are in Cirrus’, Bonanzas, and various twins that are used for cross-country travel? Which uses more fuel - a RV getting a $100 burger a half-dozen times a year, or a SR22T that goes to business events across the country 2-3 times a month?
Automotive fuel doesn’t come anywhere close to replacing 100LL, nor does 100R for the exact same reason.
BTW, the majority of new certified piston planes cannot use automotive fuel. Three of the top 5 planes are Cirrus’, none of which can use automotive gasoline. The Diamonds are also limited to aviation-grade fuel.
I do not doubt this, but the combined total of Cirrus and Diamond aircraft do not make up even 5% of the piston aircraft fleet. But that is beside the point really. No one advocating for the expanded use of Mogas is calling for an end to 100LL or whatever new, expensive, boutique fuel that may (or may not, it seems) replace it. Fact is, well over 70% of all legacy piston aircraft and nearly all new light aircraft run just fine on Mogas.
This, again, is simply not true.
Review the light aircraft sales numbers. Those Cirrus and Diamonds you are ignoring are the majority of new light plane sales and have been for many years.
In fact, the opposite is true. The majority of new light aircraft being sold in the US today and for the past decade can NOT run on automotive fuel.
Sorry the numbers show something much different.
Big Producer of Small Engines — Rotax Reaches a Major Production Benchmark
"Of particular interest to aviation enthusiasts — More than 175,000 Rotax aircraft engines have been sold since 1973. Of this number, 50,000 were four-stroke engines from the well-known 912/914 series. All Rotax aircraft engines are approved for operation with Ethanol 10, Mogas and Avgas."
Aviation fuel and the 70/30 mantra
New study shows autogas can power 80% of piston aircraft
My company is developing a new light aircraft. We would be out of our minds to use a powerplant reliant on an expensive, boutique fuel such as 100LL or its replacement. Mogas, Jet-A/Diesel, and electric are the only options.
You are improperly conflating the existing fleet with new sales, and quoting Rotax numbers that are majority EU, not North America.
The majority of new certified airplanes sold in the US use engines that cannot use automotive fuel. This is factual, based on the sales numbers of Cirrus SR20/22/T and Diamond DA42 planes.
I believe we are focused on two different things. You are concerned about the fuel for Cirrus aircraft. Diamonds can be powered with Jet-A if equipped with their Austro engines. I am focused on the entire legacy piston-engine fleet, of which the Cirrus make up a very small percentage. Fact is, all modern aircraft engines are designed to operate on either mogas, or Jet-A/diesel. Rotax, UL Power, Jabiru, the new engine on the SE-1 (the star of Oshkosh 2025), Verner radials, and the recently-anounced aircraft engines from Kawasaki are designed for mogas. Rotax has a six-cylinder, 300hp, mogas-burning prototype engine and will surely have something to replace the engines now used in the Cirrus, but without the need for 100LL or its replacement. But no mogas advocate has ever suggested that it will ever be a replacement for other aviation fuels. When I travel in Europe and visit GA airfields, Mogas is nearly always available alongside 100LL and Jet-A. I do not understand why this is not done in the US, considering 80% or more of all piston-engined aircraft run fine on it.