A California court has denied a motion from the Center for Environmental Health (CEH) asking the court to uphold a 2014 settlement with FBOs and fuel distributors that required leaded avgas to be banned once a “commercially available” unleaded alternative was available.
CEH noted that since General Aviation Modification Inc.’s G100UL is FAA-approved and selling at FBOs in California, the court should enforce that settlement agreement.
However, Judge S. Raj Chatterjee noted in the May 30, 2025, ruling that since G100UL has not gone through the ASTM process for specification, it cannot be considered “commercially available.”
G100UL was approved in 2022 after a decade of testing by the FAA through the Supplemental Type Certificate (STC) process.
In his ruling he cites declarations the court received from independent Original Equipment Manufacturers (OEMs) who opposed CEH’s motion even though the FAA’s STC for G100UL applies to their aircraft, including Piper Aircraft, Cirrus Aircraft, Aviat Aircraft, Diamond Aircraft, and Textron Aviation, which produces Beechcraft and Cessna aircraft.
“The FAA’s approval of an unleaded avgas for use in these aircraft is an important first step in the process of transitioning to an unleaded fuel for the entire GA fleet, but it is not the only step needed to ensure a safe transition,” the ruling states. “Fuel distributors and FBOs lack safety assurance without an industry consensus standard or ASTM International product specification. At present, G100UL is not commercially available for distribution and sale in the U.S. largely due to the fact that it does not have an ASTM International product specification.”
GAMI’s George Braly says the ruling is “disappointing, but not unexpected.”
“It was resolved without courtroom testimony and no opportunity to cross-examine witnesses,” he notes.
He points out that the motion wasn’t to ban 100LL, but for the FBOs and fuel distributors to uphold an agreement they made years ago to sell only unleaded fuel once one becomes commercially available — “which is G100UL,” he says.
In his ruling, the judge also noted that GAMI “elected not to pursue an ASTM specification and has elected not to disclose certain specifications and information regarding G100UL,” the ruling notes. “G100UL has not been subject to ‘peer review’ because GAMI declines to share information without a confidentiality agreement. While that might be GAMI’s rational business choice, that decision has inhibited the formation of a general industry consensus by, among other things, preventing industry stakeholders from adequately vetting the fuel. These factors, in light of the concerns raised regarding the safety and compatibility of G100UL, such as whether it degrades tank sealant, further militate against finding that the fuel is commercially available.”
“The court finds that there are safety and compatibility issues that need to be vetted,” the ruling continues. “The court further finds that material industry stakeholders, including significant manufacturers of the aircraft and engines with which G100UL will be used, need to have their concerns addressed and satisfied before a general consensus on safety, compatibility, and efficacy can emerge.”
The judge acknowledges that general aviation aircraft owners “are likely to be reluctant to use fuel in their aircraft when the pertinent manufacturers have disapproved of that fuel and have asserted that the use of such fuel would void warranties. Absent a general industry consensus that the fuel is safe, compatible, and effective, aircraft users are likely to be reluctant to use the fuel.”
But GAMI’s Braly said G100UL was presented to ASTM for review.
“Most people are unaware that we did submit information to ASTM,” Braly says.
They then discovered that a “major oil company” which had a representative on the committee had taken GAMI’s confidential information and was trying to file competitive patents.
“Once the FAA recognized this, they said we will make a determination that is equivalent to an ASTM spec,” Braly said. “The FAA has, in fact, made a determination of an FAA-approved specification,”
The specification, which is available on the G100UL website, notes that: “The FAA has, in fact, made a determination that this Specification and Standard for a High Octane Unleaded Aviation Gasoline provides, not only an equivalent, but, in fact, an enhanced level of quality control…as compared to the traditional governmental, military, or industry voluntary consensus based standards which have previously defined and controlled the production and distribution of aviation gasolines used for spark ignition piston engines.”
The court ruling also notes that G100UL does not apply to the entire general aviation fleet, including piston-powered helicopters, light sport aircraft (LSA), or experimental aircraft.
But Braly points out that there is only fuel left in the FAA’s Piston Aviation Engine Fuels Initiative (PAFI) from LyondellBasell/VP Racing and officials from that company have already said — even before the process is complete — that there is no way the fuel will suitable for the entire general aviation fleet.
He points out that G100UL has been approved by the FAA for all piston aircraft.
But according to the California judge, the motion to declare GAMI’s fuel commercially available is “premature.”
“Requiring the public to use a particular brand or type of avgas requires consideration of highly complex and technical health, safety, and compatibility issues,” his ruling reads. “The FAA is studying these issues; the California Legislature is addressing these issues; the aviation industry with its many stakeholders is providing input into the process; and various unleaded fuels are being vetted. This motion, in effect, seeks to circumvent that public-private infrastructure to impose the use of G100UL by way of a motion under a stipulated Consent Judgment. Courts in general should be careful to avoid assuming general regulatory powers and determining complex economic policies.”
“The science of aircraft fuel will continue to develop” he concludes.
What’s next for GAMI?
The company will continue on its quest to find more airports to carry the fuel, according to Braly.
Right now there are two airports in California, two in Texas, and one in Mississippi that offer G100UL for sale.
For more information: G100UL.com
The entire unleaded fuel debate and approval process is a hot mess controlled by conflicting interests, and complicated by injections of misinformation from all sides. As aircraft owners, we find it impossible to navigate the maze of opinions and counter opinions. AOPA’s mixed messages have not helped in this regard. For now we are forced to keep burning 100LL in our old O-200 that was designed to run the long gone 80/87 av gas. The mogas STC is not an option for us as you can’t find ethanol free gasoline in California or many other states. A little known fact is that the lead content of 80/87 was 0.5 g/gal vs 2.1 g/gal for 100LL. In other words our poor old engine is forced to run on fuel that contains four times the lead content of the older fuel. Somebody must have had a wicked sense of humor to call the newer fuel Low Lead!!! We’ve seen the results over the past few months diagnosing power loss as a result of sticking valves and severe build up on the valves themselves at only 800 hours. We are not alone in this problem: every few days I hear of another owner in the Cessna 150 group talking about similar issues. 94UL would be a good solution for us and many other GA aircraft but FBOs are understandably not enthusiastic about installing tanks for several different fuels. It’s time for everybody to get together and solve the unleaded fuel issue once and for all – this is not a moon shot!
We’ve had the solution for nearly 50 years – it is called Mogas, ethanol-free, lead-free gasoline, available and tens of thousands of suppliers across the country. Rotax, by far the leading producer of aircraft powerplants, designs all of its engines to run on Mogas. They are laughing all the way to the bank when reading about the belly flop that has been the futile attempt at finding a drop-in replacement for Avgas.
I was at Oshkosh last year. The University of North Dakota stopped using this stuff. It was destroying their engines. Apparently he was burning up valve seats.
John, I think you have the wrong product.
You mention “This Stuff” in the case of UND was UL94 not G100UL. Is G100UL any good, I have no idea. But lets let each product succeed or fail on it on merits.
https://avweb.com/aviation-news/citing-valve-damage-und-drops-unleaded-fuel-and-returns-to-100ll/
There are two sides to the valve story. Here is some information about valve lead deposits:
Lead deposits, primarily lead oxybromides from tetraethyl lead (TEL), can cause significant damage to aircraft engine valves, particularly the exhaust valves. These deposits can harden, creating metallic layers on the valve stems, leading to valve sticking, reduced engine performance, and even catastrophic failures.
I so wish there were more airports with UL91 or UL94 so the majority of us aircraft owners won’t have to worry about lead damaging our aircraft, with lead damaged valves, fouled plugs, lead contaminated oil, and lowered TBO’s. Not to mention the guilt of damaging the environment and creating a health hazard. This should be happening now not 4 years from now. Of course it could be never, the way that the AOPA pushes leaded fuel, as if they own stock in the company that supplies the lead.