This story was updated with corrections about Swift Fuel on June 20, 2023:
You have questions about general aviation’s transition to unleaded fuel.
So do aircraft manufacturers, the manufacturers of piston engines, FAA officials, and general aviation’s advocates.
That was apparent June 5, 2023, during an online update of EAGLE — Eliminate Aviation Gasoline Lead Emissions — an initiative launched in 2022 with the goal of eliminating lead in aviation fuel by 2030.
A lot of heavyweights participated in the update, including the head of the FAA’s certification services, the top guns at Textron Aviation, Piper Aircraft, CubCrafters, and Lycoming, as well as the Aircraft Owners and Pilots Association, General Aviation Manufacturers Association, Experimental Aviation Association, and more.
One word could sum up the update: Transparency.
Without it, the FAA, engine manufacturers, aircraft companies, FBOs, and you — the general aviation pilot and aircraft owner — can’t transition to unleaded fuel.
“We need to certify and test these fuels against the ASTM standards,” said General Aviation Manufacturers Association President Pete Bunce. “We’re in new territory — we need to know the specifications and the chemical composition of these fuels. We need to know that our customers are going to be safe.”
Textron Aviation’s Ron Draper echoed Bunce’s comments.
“We’re excited by the innovation in fuels,” he said. “But we desire more transparency and the ability to test these fuels in our airplanes.”
He noted that the company — which has produced more than 250,000 airplanes with a “vast majority” still flying today — hasn’t had the chance to test any of the unleaded fuels that are vying to replace 100LL.
Neither has Piper, CubCrafters, or Lycoming.
“We can’t endorse it until we test it and fly the heck out of it,” Draper said.
But why haven’t they tested it yet? Because there just isn’t enough of the candidate fuels available.
And what that means is that we still don’t know what we don’t know.
What Do We Know?
Some progress has been made.
There are four fuels that are possible contenders to replace 100LL, with the hope that all four get approved so there will be some competition in the marketplace.
Two have already been approved through the STC process.
Swift Fuels was approved in 2015 to sell its UL94 avgas. It is now available at 35 airports nationwide. Pilots and aircraft owners who want to use this fuel must purchase an STC.
The company is now working with the FAA on a 100% replacement to leaded avgas, called 100R, using a combination of the STC and Piston Aviation Fuels Initiative (PAFI) programs, according to company officials.
“All our unleaded fuels will enter the marketplace with an ASTM International fuel specification as a result of our extensive industry and OEM collaboration,” noted Swift Fuels’ Chris D’Acosta.
The second contender is General Aviation Modification’s G100UL, which was approved in September 2022 through the STC process.
GAMI officials are in the process of commercializing the new fuel, with hopes that it will be at airports in the next year or so.
The other two candidate fuels are going through the FAA’s Piston Aviation Fuels Initiative (PAFI).
One, from LyondellBasell/VP Racing, is nearing completion of its “final initial phase” testing, while the other, from Phillips 66/Acton, is set to begin its “final initial phase” testing soon.
If these two fuels are approved, the FAA will give them fleet authorization. If that happens, the FAA will tell aircraft owners “what they’ll have to do to use the new fuel,” explained Lirio Liu, head of the FAA’s certification services and co-chair of the EAGLE initiative with AOPA President Mark Baker.
“Regardless of the approval path, the FAA doesn’t approve fuel,” Liu explained. “We approve the use of fuel.”
What Don’t We Know?
But so many questions remain about how the new fuels will work in a general aviation airplane — especially in a plane that’s 20 or 30 years old.
Of course it has to work in the engine, but it also has to be compatible with other aircraft parts, such as fuel pumps, valves, fuel lines and fittings, filters, and more.
There’s also a lot of questions about other key characteristics of the candidate fuels, according to Lycoming’s Shannon Massey, including:
- Octane
- Toxicity: “It’s important we don’t replace one fuel with another that’s also harmful.”
- Corrosive properties
- Density: She noted that the aromatics used in the new unleaded avgas are heavier than 100LL, which could affect an airplane’s center of gravity and other performance factors
- Stability: “What happens when it is stored in tank? We have to make sure the octane doesn’t drop.”
- Production: “We need a fuel that is producible repeatedly.”
Questions about these items — and more — are flooding in to the aircraft manufacturers.
Piper’s John Calcagno reports the company is getting calls from flight schools, insurance companies, and customers with questions about the impact the new fuels will have on the more than 80,000 Piper aircraft that are flying around the world — most of which are well over 20 years old.
“How will the new fuel impact these older airplanes,” he asked. “It’s very important that we get this right.”
“Our customers rely on fuel to be right,” he continued. “We don’t want to take that away from them.”
And what about experimental aircraft?
EAA’s Jack Pelton noted that STCs are not applicable to experimental aircraft. And as the homebuilder is the manufacturer of the aircraft, it will be up to them to test the new fuels to ensure they are compatible with their aircraft.
And that’s a big deal because about 20,000 experimental amateur-built aircraft are registered every year.
Asking homebuilders to become fuel testers is taking things “too far,” he said.
“Fleet authorization is the way to get around that,” he acknowledged.
He also brought up a point no one else had about the “availability and acceptance” of the new fuels: Economics.
How much will the unleaded fuel cost?
“We don’t have information on that,” he said.
Safety is No. 1
Getting it right is more important than getting it done quickly, all of the presenters noted.
“We’ve been at this a long time,” said GAMA’s Bunce.
“We are making progress, but there is still a lot to be done,” AOPA’s Baker added. “I’ve often said that if this was an easy thing to do, it would have been done already.”
“All the pieces of the puzzle have to come together,” the FAA’s Liu noted. “That’s what EAGLE is set up to do.”
And while that is happening, it is imperative that 100LL remains available to general aviation pilots.
“We’re pushing back on communities that are trying to ban 100LL,” Baker said.
Two airports in California — Reid-Hillview Airport in East San José and San Martin Airport — have already banned 100LL, with efforts in other communities squelched by GA advocates — so far.
And the initiative is facing one other time pressure: In October 2022, the Environmental Protection Agency (EPA) released a proposed finding of endangerment regarding lead emissions from piston aircraft. This is the first step in a very long process expected to take several years to ban lead from avgas.
The EAGLE initiative hopes to beat that ban by finding a solution by 2030.
Learn more about EAGLE at FAA.gov/Unleaded.
I think Rick Durden, Senior Editor Aviation Consumer sums the Unleaded Gas vs. EAGLE concerns succinctly. From the Dick’s June 2023 editorial:
UNLEADED AVGAS: EAGLE’S DISINFORMATION CAMPAIGN
The State of California is now fully aware that there is a viable, FAA-approved unleaded avgas—G100UL—and, from what I’ve learned from multiple sources, is demanding that it be sold at all California airports by the end of this year. That’s great news to pilots and especially to FBOs in California that are subject to a lawsuit requiring that they sell the lowest lead commercially available avgas or be subject to sanctions. They now have a way to avoid potentially millions in court-ordered sanctions if they keep selling 100LL.
One would think that the folks at EAGLE (Eliminate Aviation Gasoline Emissions by 2030) would be delirious with success and hanging “Mission Accomplished” banners on tankers hauling unleaded avgas across the nation. Sadly, perhaps EAGLE recognizes that if it declares victory and admits it did what it was supposed to do—get a 100 percent drop-in unleaded avgas to general aviation pilots—before 2030, it’s out of business and will miss out in millions in federal money. Accordingly, EAGLE, through its members, initially stalled, offering vague excuses about additional testing for G100UL (to “build confidence”) even though it went through 12 years of testing by the FAA and further testing by the two largest OEM airframe producers who reported no issues in their flight testing. Then EAGLE members started an active disinformation campaign against G100UL, asserting that because it was FAA-approved and had an FAA spec, that it was not satisfactory unless it also had an ASTM (American Society for Testing and Materials) approval and spec. Some EAGLE members made false statements that FBOs would only be protected from liability in a lawsuit regarding avgas if the avgas had an ASTM spec. I learned that one went so far as to falsely state that it’s illegal to sell an avgas that doesn’t have an ASTM spec.
Those are lies. The FAA has long recognized that there are two methods of getting an avgas approved: via the FAA or via ASTM coupled with more FAA testing. One is not better than the other or preferred. It is not illegal to sell avgas that has an FAA approval/spec and not an ASTM approval/spec—just as it’s not illegal to sell an avgas that has an ASTM approval/spec and not an FAA approval/spec.
Having an ASTM approval/spec will not protect the seller of avgas from legal liability just as having an FAA approval/spec won’t. I retired after practicing aviation law for 42 years, much of it defending aircraft and component manufacturers. The fact that a product—airplane, landing gear, avgas—met a spec or received federal approval does not prevent the manufacturer or seller of that product from liability in a lawsuit. The issue is whether the product was defective or was negligently designed and/or manufactured. Compliance with a particular standard or spec is just one piece of evidence the jury may consider in determining liability. ASTM approval is not a get out of jail free card—just as FAA approval isn’t. A lot of aviation manufacturers have been found liable for products they sold that met ASTM and/or FAA specs.
Further evidence of EAGLE’s unwillingness to work toward success is that two of the EAGLE participating fuels, Lyondell/VP Racing and Phillips 66/Afton Chemical, contain manganese—which has long been unacceptable in fuel because of combustion chamber and spark plug deposits. Why didn’t EAGLE call foul immediately? EAGLE should never have accepted either fuel into a taxpayer program. Not surprisingly, those fuels have recently been withdrawn to be “reformulated.” It sure looks like petroleum giant Phillips is now getting a government subsidy to do its R&D via EAGLE. This has been raising the question—who is EAGLE working for, the oil companies or aircraft pilots/owners?
I keep thinking of the phrase used by the FAA’s Office of the General Counsel when it evaluated a long-delayed project: “The FAA now expects to see conspicuous progress.” Fortunately, all “conspicuous progress” accomplished thus far was by private enterprise. From where we sit, EAGLE’s actions are years away from a similar description. In another opinion piece in our April 2023 issue, we suggested, tongue in cheek, that because of continued foot-dragging, EAGLE change its name from a glorious soaring bird to what it really is, a flightless one—KIWI, Keep Industry Waiting Indefinitely. I renew that recommendation.
I also call on AOPA and EAA to evaluate their posture in the EAGLE process to make sure that they are truly supporting their members who need unleaded avgas and not organizations trying to delay its implementation out of what seems like misguided self-interest. —Rick Durden
This EAGLE will die a natural death, likely in the next few years. Yes, there is stubbornness to insist on an ASTM solution, but a few years from now, when airplanes are doing just fine on the GAMI fuel, will this EAGLE survive? No, and few will care.
I own and fly a 45 year old twin that burns lots of gas. I’m not interested in being a test bed to fulfill this pie in the sky fantasy that this new fuel will supposedly help save the environment. I mean, I put my family in this thing. It’s merely fantasy. Our old air cooled piston jobs were made to run on leaded fuel. Lead is actually a lubricant by the way. Its 100 year old technology. But I’m a realist and I’m aware that it will be forced upon us just like the ethanol debacle was. How many small engines were ruined before we realized that they should be run on the ethanol-free gas?! Its not like we can pull off to the side of the road when a component, filter, gasket, etc fails because of this fantasy. And I’m certain that it will be even more expensive than the 100LL that we’re currently using. All for what? I’m already considering moving to a Jet-A burning aircraft because of this because I know its coming.
Is anyone thinking of how many variants of fuel an airport will have to have? Now it is two, Jet A and 100LL. Now we are looking at how many variants? I can see having to flight plan based on what airport sells the version of fuel I need. Not the most economical way to fly.
All the while for the vast majority of light aircraft owners there is relative inexpensive, proven Mogas option, available most everywhere, STCs for most aircraft for Mogas, and nearly all new aircraft engines are designed to operate on it. We are so backwards in this country.
If the authorities would mandate a final date for 100ll, this process would become much quicker.
So far, however, sandbagging helps the airplane and engine manufacturers save lots of money and allows them to use technology developed in the 40s and 50s until today, even in brand new airplanes. Adapting cylinder heads and fuel systems to unleaded fuel is no witchcraft or even rocket science. But sandbagging is cheaper and requires less thought.
We feed all of our lyconosaurs unleaded petrol (gas) since more than a decade without any problems. And yes, they do not need 100 octane fuel.
But the oil companies have ethanol free 100 octane fuel available. But of course, we will have to adapt what we use to what they have, as our small market is not really attractive for big oil.
Welcome to the world of another Bogeyman and the Scama-A-Rama game of let’s make some more money off the unsuspecting recipients, with bureaucratic blender oversight.
How about an detailed update on where G100UL really is now.
GAMI jumped over multiple FAA hoops multiple times before being approved. If I had a plane, I would have no problem burning GAMI100UL in it.
I bought the GAMI 100 octane unleaded fuel STC for my Cessna Cardinal (200HP IO360 for which UL94 will not work).
I have zero concerns whether it will work well or not. GAMI spent the better part of a decade testing it in every configuration, scenario, longevity, ratios with other fuels, and everything mentioned in this article as a concern but didn’t bother to mention as already 100% resolved by GAMI.
This fuel solves the problem.
It is being distributed. It works.
There is no confusion in my mind or others’ minds who bought the STC.
A good place to engage “transparency” is with the use of ASTM D7826-23. GAMI’s STC process, for all the good intention and elaborate testing it provides, offers fuel with approval for a wide range of engines, but in the end, it’s still approval for one fuel to one aircraft. And each one of those aircraft now shoulder the responsibility to determine how that fuel responds in their equipment and for their mission. An STC is an alteration, not a guarantee.
It been so sad to watch this effort over so many decades to get a unleaded 100 octane fuel for piston aircraft, when the real truth is it will never happen, but it appears no one will live up to the truth. We are so lucky that at least there is UL 94. The manufacturers should have already been designing all new aircraft to use the 94 alternative. Modifications can be made to current engines just like it was done when 115/145 was discontinued. .
Amen.
But when you say “at least there is UL 94” – there could be, if any airports had it.
I’m 63. I expect I will have aged out of flying by the time this stuff shows up at airports.
It should be understood that the introduction of a new gasoline chemistry can affect engine components. The introduction of ethanol gasoline has caused the failure of engine seals and the rubber blatters in the fuel pumps of older & European vehicles.
That’s exactly right, Mr. Peter Roberts. That happened more than 30 years ago. Fortunately it happened in “terrestrials” vehicles and in a lot of them, even in those who have suffered some modifications. Some troubles demanded to stay in the shoulders of roads. Something different must be thinking in a/c reality. That’s what we must face and solve without any foreseeable danger,