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Transitioning to Unleaded Aviation Fuels

Getting the lead out of aviation fuel won’t be easy, and the time to do it is short.

Transitioning to Unleaded Aviation Fuels

At the General Aviation Manufacturers Association (GAMA) meeting in Washington, D.C., this spring came the blockbuster announcement that the industry and the FAA are 100% behind the retirement of 100 Low Lead aviation gasoline and the transition to nothing but unleaded aviation fuels by 2030, which is a little less than nine years away. 

The announcement was made by then-outgoing and now-former FAA Administrator Steve Dickson, a parting gift to aviation, perhaps, as he vacated the agency for reasons unrelated to avgas. It’s an issue, by the way, that no one in Washington except the Environmental Protection Agency (EPA) cares much about. But the EPA could ban unleaded aviation gas altogether if it so chooses, and at some point it surely will. The announcement at the GAMA event was largely a signal to the EPA, if it was watching, that general aviaton understands the need to get rid of 100LL fuel. 

Which is a big deal. For around 50 years, 100LL has been the only fuel in the country for piston-powered aircraft and the only leaded fuel used for any transportation segment whatsoever in the United States. It’s a wonder the EPA has let it exist for as long as it has, and that happened only because 100LL represents a tiny fraction of the fuel used in aviation as a whole, with Jet A (diesel-like) fuel predominating.  

If you’re shaking your head that this kind of industry-wide commitment is only happening now instead of decades ago, you’re not alone. Aviation is a dinosaur, insofar as our use of lead additives in our gasoline is concerned. The automotive industry turned to unleaded fuel in a major way starting in the mid-1970s. By the mid-’80s, leaded auto fuels represented less than 10% of the fuel used. By 1992, California, the nation’s largest car market and de facto regulator of many things automotive, including fuel economy and emissions, had banned leaded auto fuel. By 1996, it was banned throughout the United States. That was 26 years ago now. Leaded fuel was almost entirely phased out 10 years earlier, and 10 years before that, it was no secret to anyone that lead was on its way out. That was more than 40 years ago. 


Though to be fair, 40 years ago, aviation did respond forcefully, though not by moving away from leaded fuel but by coming up with a strategy that appeared to go a long way toward that goal. This it did by introducing a new fuel, which in a marketing coup it named “100 Low Lead,” which gave everyone the impression that the new fuel was a huge improvement. It wasn’t. 

The new 100 Low Lead formulation was, in fact, lower in lead than only one of the fuels it replaced, and the name leads the public at large to assume that our low-lead fuel must have very small amounts of lead in it, but 100 LL has as much lead in it as auto fuel of the early 1970s. It does have about half the lead as the old leaded 100 octanes, so that’s an apparent gain, at least for the airplane engines that needed 100/130 octane fuel previously. But 100 LL has a lot more lead than 80 octane, which became a scarce commodity by the late ’70s and unavailable by the end of the ’90s. 

How much was the difference in the total lead output with the entrance of 100LL on the scene in the late ’70s/early ’80s? There are so many variables, it’s impossible to say for sure, but it was a lot less of an improvement in our lead emissions than you might think, if it was an improvement at all. Regardless, as an industry, we’ve been banking on the appearance of a huge improvement for the past few decades. 


So when airport authorities start using the presence of lead as an excuse for shutting down airports, they are not entirely to blame. Though no one is stepping up to accept responsibility, no one is denying that light GA, along with the FAA, bears the brunt of it. 

So we find ourselves today, some 40 years and change down the road from when auto gas started to get the lead out, suddenly getting serious about going to unleaded fuel. It’s a bit much. The self-congratulatory tone, especially, is hard to take. After all, the FAA has been hard at work shepherding the creation of unleaded aviation fuel for a couple of decades now with nothing major to show for it. Sweden, by the way, has had an acceptable unleaded 90/95 octane fuel since 1991. Given the historical context of the debate, the announcement by the FAA that it was getting behind phasing out leaded avgas by next decade seems a little like a 12-year-old who gets caught smoking responding by proudly announcing that they will be quitting altogether by the time they’re 21, as if that’s an accomplishment. It isn’t. It’s deflection. All that really happened is that they got caught smoking and they have no immediate plans to quit.

And GA has gotten caught, though to be fair, it couldn’t go cold turkey if it wanted to. The much-reported- upon move by the Santa Clara County Commissioners in the Bay Area of California to ban 100LL at its airports and to push for the closure of one of the busiest GA airports in the country, Reid-Hillview, is something light GA should have seen coming. Forty years ago. And done something real about it. 


So we find ourselves today, some 40 years and change down the road from when auto gas started to get the lead out, suddenly getting serious about going to unleaded fuel. It’s a bit much. The self-congratulatory tone, especially, is hard to take. 

Getting to an Unleaded GA

A few weeks after the big GAMA reveal, at the Sun ’n Fun 2022 fly-in, the heads of three general aviation member organizations discussed the potential pathway to a 100LL avgas future—a future, they all seemed to agree, that is likely to start in 2030, a date that will be mandated most likely by the EPA, and about which aviation authorities are likely to have little to no say. 

The discussion was framed by outgoing Sun ’n Fun head John “Lites” Leenhouts, who wasted no time in proposing, perhaps not directly, that GA groups band together to fight the banning of 100LL, which could greatly negatively impact the industry. “If they reduce the availability of it, people are going to be pushing the envelope…and it’s only a matter of time before someone runs out of fuel,” Leenhouts said. “It will just happen more often, and we can’t let that happen.”


Experimental Aircraft Association President and CEO Jack Pelton then wasted as little time in correcting the notion that GA had any say in the matter. “This is an international problem, it’s not just the U.S. alone…The removal [of lead] is an issue that will affect the entire world,” Pelton stated, responding to Leenhouts that “fighting” the end of 100LL is a train “that has absolutely left the station.” The determination, he added, could come possibly this year, when the EPA issues an “endangerment finding.”

This will lead to a rulemaking process, nearly identical to how aviation rules are promulgated, that will establish a timeline, most likely, he said, by the year 2030. Federal agencies often begin required adoption of rules on the first day of the year. If that comes to pass, aviation has just over seven years until 100LL goes away.

Shell Fuel Truck


Are We Ready for a Lead-Free GA?

The short answer is, not even close, and the more you learn about the circumstances, the shorter the time seems. “The clock is ticking,” Pelton added. “It’s a very complicated problem…A lot of people ask me about the process of finding a fuel, and I say, that’s [just] a piece of it. You still have distribution, you still have storage, you still have [the question of whether] petroleum companies will step up and make it.”

Aircraft Owners and Pilots Association (AOPA) President and CEO Mark Baker concurred with Pelton about the complexity of the issue, saying, “We don’t want to be the last [industry], general aviation, putting lead in the air, but we are. We would have liked to have [had] solutions 20 years ago, but
there’s simply not been a drop-in solution that’s competitively priced and available now. There might be, pretty soon,” he said, “and we’re big advocates for that.” But Baker emphasized, based on industry workgroups, that “no later than 2030…we will no longer be selling or distributing leaded fuel in North America.”

Baker put things in perspective by laying out the small market, relatively, that avgas represents. “We use about 180 million gallons of avgas a year, which is equivalent to three or four hours of car gas [there are 8,760 hours in a calendar year].” It’s a tiny market, and Baker emphasized that the process of moving to an unleaded fuel must be reasonably profitable to the refiners.


Perhaps the most chilling note of the roundtable was Baker’s reminder that there is just one facility in the world, in Liverpool, England, that makes the lead that goes into 100LL, and there is no guarantee that it will continue doing so for any predictable length of time. Baker thought it “very unlikely” that the product would continue to be made over the next five to 10 years and punctuated the subject by saying, “We have a lot of things stacked against us, and the thing that I am most concerned about today is keeping low lead available until we find a solution.”

And he underscored the criticality of the issue, pointing to airport authorities in California who have banned the sale and distribution of 100LL at their airports, expressing concern for the safety ramifications were pilots to be tempted to use unleaded fuel in higher-horsepower engines. “Thirty percent of our airplanes,” he said, “burn about 60% of our gas,” making clear that the need for a viable 100LL replacement is not a niche problem but one central to the vitality of general aviation.

GAMA President and CEO Pete Bunce said that refining higher-octane unleaded fuel is possible but expensive, and he repeated his concern that a replacement fuel (or fuels) be a drop-in replacement for 100LL, suggesting that it is something aviation needs to do before 100LL goes away.


When asked about the process for approving new fuels, Bunce said the approval process would be no different from how fuels are now approved, which is through the process of industry consensus standards, such as ASTM or SAE. He seemed to be confident that once a suitable fuel is developed, its adoption would not be as big a hurdle as the actual development of that fuel.

Bunce repeated that, ideally, the solution might be the development of multiple fuels, as competition tends to help drive prices down, but clarified that the fuels would have to be universally compatible with each other, as pilots fly across multiple parts of the continent and are certain to use multiple fuels along the way if those fuel types are regionally distributed.

In response to a question from Plane & Pilot about the potential cost differential between 100LL fuel and a 100LL replacement, AOPA’s Baker said, “We don’t have total visibility into that,” but added that, “if we do have a fuel that is fungible, that is, can be dropped in any tank, can be hauled by any truck, can be delivered across the country, perhaps in pipelines…there’s a potential long term for it to be a lower cost.”


But whether such a future will arrive or not remains to be seen. As Bunce pointed out, the process of this changeover to unleaded fuel is a complex
one, with the steps including (but not limited to) the development of the fuel, its approval, refiners gearing up to produce it, and getting the distribution network up to speed on it. It’s a complex process with risk at every step along the way. 

And, the three leaders agreed, we don’t have much time to get there. 

Going Direct: Industry Commits to Lead-Free Avgas By… 2030?


Life After 100 Low Lead: GA Leaders Say Time is Short, the Problem, Complex.


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