By Ronnie R. Gipson Jr.
In the first six months of 2025, two significant legal decisions occurred which signal that opponents to the use of leaded aviation fuel must throttle back on their attempts to prematurely eliminate the use of leaded aviation fuel. The first significant decision was the Federal Aviation Administration’s March 24, 2025 ruling on a complaint against Santa Clara County, finding that the county took unlawful actions designed to prohibit leaded aviation fuel sales at its two public use airports.[1] The second significant event was the order by Alameda County Superior Court Judge Chatterjee, denying an injunction request to require the sale of unleaded aviation fuel in a number of airports in California.[2] Taken together, these two events signify administrative and judicial support for the continued use of leaded aviation fuel until the Federal Aviation Administration (FAA) and industry come up with a commercially available “drop-in” unleaded fuel that can be utilized throughout the general aviation fleet. More importantly, these two decisions represent a strong signal to the promoters of unleaded aviation fuel who champion replacing 100LL aviation fuel without a viable drop-in replacement that is sanctioned by the federal government and industry stakeholders. Promoters of unleaded fuel must exercise restraint and refrain from overzealous attacks because a resolution is forthcoming.
The FAA Decision
In late 2022, tenants at the two Santa Clara County, California (County) airports [Reid-Hillview (RHV) and San Martin (E16)] along with the Aircraft Owners & Pilots Association filed a formal complaint with the FAA alleging that the County unreasonably prohibited the sale and use of 100LL fuel in violation of FAA grant assurances.[3] Specifically, the complainants argued that the County violated Grant Assurance 22(a) Economic Nondiscrimination, by denying reasonable access to leaded aviation fuel at Reid-Hillview and San Martin airports. Additionally, the complainants alleged a violation of Grant Assurance 22(f), Economic Nondiscrimination, by the County for unreasonably denying aircraft owners the right to self-fuel their aircraft with leaded fuel at both airports. Finally, the complainants alleged that the County violated Grant Assurance 24, Fee and Rental Structure by claiming that the leaded fuel sales prohibition resulted in a marked decrease in fuel sales at both airports. The County denied that the issuance of its January 1, 2022, order, allowing the exclusive sale of unleaded aviation gas, violated any federal grant assurances. The County asserted that it issued the January 1, 2022, order to protect public health and welfare due to the potential for elevated lead levels in children living near the airports. After evaluating arguments from the complainants and the County, the FAA determined that the County violated Grant Assurances 22 (a) & (f), Economic Nondiscrimination; as argued by the complainants.[4]
The FAA decision was based on contract law. The Grant Assurances obligated the airports to comply with certain conditions; included within the agreements that the airport sponsors signed when accepting federal money from the Airport Improvement Program (AIP).[5] In the complaint against Santa Clara, the tenants rightfully complained that the County’s actions prohibiting the sale of leaded aviation fuel represented a breach of the contract. Specifically, the complainants alleged that the County’s leaded fuel prohibitions denied the public reasonable and nondiscriminatory access to publicly funded airports. The Complainants highlighted the fact that the FAA issued a Supplemental Type Certificate for G100UL, which is a 100-octane unleaded fuel. However, the complainants rightfully argued that the G100UL fuel is not certified for use in all piston engine aircraft. On this basis, the prohibition of leaded aviation fuel sales to owners/operators at the two airports by the County was premature because the fleetwide unleaded aviation fuel was not readily available.
Exactly how did the County violate Grant Assurance 22, Economic Nondiscrimination? The first act taken that violated Grant Assurance 22 was the County’s approval of Resolutions 36 & 37 directing its own county administrators to prohibit the sale or use of leaded fuel at both airports. Next, the County then enacted a self-serving exclusive right to sell unleaded aviation fuel. In adjudicating the Grant Assurance 22 violation, the FAA noted that ongoing demand exists for 100LL fuel at both Santa Clara airports. The FAA referenced the more than 242,000 aircraft operations at both airports in 2020 combined with the fact that 32% of the national piston general aviation aircraft fleet needs 100LL fuel to operate. A ban on 100LL fuel sales at the two County airports would have effectively removed both airports from the National Airspace System, countering the purpose behind the award of grant money to airport sponsors through the Airport Improvement Program.[6] The FAA concluded that the County’s prohibition on the sale or use of 100LL at its airports was an unjust, unreasonable violation or breach of Grant Assurance 22.
Grant Assurance 22 in part provides that an airport sponsor will not exercise a right or privilege that serves to prevent any operator on the airport from performing services on their own aircraft such as self-fueling. The County required that operators at the two airports could engage in self-fueling operations, but only with fuel obtained from the County (i.e. unleaded fuel which the aircraft cannot use). Thus, when the County eliminated the utilization of 100LL fuel at both airports, that move effectively terminated operators from engaging in self-fueling operations because their aircraft required 100LL fuel. Based on the County’s actions, the FAA concluded that the County’s denial of its commercial tenants, who were aviation service providers, the right to self-fuel their aircraft with 100LL fuel amounted to a violation of Grant Assurance 22.
The Denial of the Center for Environmental Health’s Injunction
In a case venued in the Alameda County Superior Court of California, the Center for Environmental Health (CEH) filed a motion for the court to exercise its injunctive powers to force more than 20 public use airports to sell G100UL, an unleaded aviation fuel, which had previously been approved by the Federal Aviation Administration (FAA).[7] At the time of the court filing, the Federal Aviation Administration issued a Supplemental Type Certificate for G100UL which is an unleaded aviation fuel. The Supplemental Type Certificate designation for the fuel means that the fuel can only be used in specific engines which are used in specific aircraft. G100UL is not readily available or approved for use in every make and model of general aviation aircraft in the national fleet.[8] In previous litigation between the plaintiff, CEH, and the defendants, comprised of fixed base operators and fuel distributors, a consent agreement was entered into by the parties where the defendants agreed to purchase and sell aviation fuel with the lowest concentration of lead approved for aviation use that is commercially available.
The parties to the litigation were not the only people weighing in on the issues in contention. Industry stakeholders including the General Aviation Manufacturers Association, the National Air Transport Association, aircraft manufacturers such as Cirrus, Piper, and Diamond; along with aircraft owners and pilots weighed in with arguments as to why CEH’s push for mandated use of the unleaded fuel was inappropriate and premature. The industry stakeholders provided firsthand evidence to the argument advanced by the defendants that the requirement to use the G100UL unleaded fuel was premature. Collectively, this group of stakeholders raised concerns about G100UL eroding fuel tank sealants in their aircraft; as well as the safety and compatibility of G100UL with aviation piston engines.[9] The group also highlighted the fact that the G100UL fuel had not been subjected to the rigorous testing of the industry’s peer review certification process for international aircraft parts. Additionally, the defendants highlighted that GAMI the maker of the unleaded fuel, declined to seek approval of the fuel by the American Society for Testing and Materials (ASTM).
ASTM approves aviation parts for compliance with international standards.[10] The failure to secure an ASTM approval means that G100UL fuel has not been made available to engine manufacturers for testing in their engines. In the absence of aviation industry vetting of G100UL, fuel manufacturers have not ramped up the infrastructure to manufacture and deliver G100UL to point-of-sale pumps in sufficient quantities to supply 24 airports. Equally important, several aircraft manufacturers along with two general aviation engine manufacturers issued statements notifying owners and users of their products that the G100UL fuel had not been approved for use in their products. These statements of disapproval provided notice to the consumers that should the users elect to use the G100UL fuel, then the accompanying product warranties; for the aircraft frame and the engines, would become null and void. Without adequate peer reviewed testing, the use of G100UL places the aircraft’s airworthiness into question, which can prevent the operators from using the plane until a remedy is found for any unforeseen problem caused by using the unleaded fuel.
As a result of the concerns raised industry wide, Judge Chatterjee ruled that the G100UL fuel did not have the status of a “drop-in” replacement sanctioned by the FAA; and the G100UL unleaded fuel was not yet commercially available to warrant the Court exercising its equitable powers to force the defendant FBOs and distributors to abandon 100LL fuel. Judge Chatterjee explained that the phrase, “approved for aviation use” meant that an unleaded fuel must be approved by the FAA for use in the entire general aviation fleet nationally and not just a select few aircraft, which is the case with a Supplemental Type Certificate. The G100UL fuel, which holds only a Supplemental Type Certificate, does not meet that requirement. Accordingly, the request for an injunction was denied. However, the denial of CEH’s request for an injunction is not the end of the story. The FAA Order and the denial collectively signify two points. First, the time for the use of leaded aviation fuel will end. Second, the cessation of using leaded aviation fuel must occur with the cooperation of governmental, regulatory authority and industry stakeholders so as not to jeopardize safety and the economic machinations of the entire general aviation industry.
It is unfortunate that Judge Chatterjee’s ruling was a trial court order and not an appellate court decision. As a trial court order, the judge’s decision has no precedential value, which means that the Court’s ruling does not bind other courts in California presented with similar issues related to the use of unleaded aviation fuel.[11] Despite the lack of precedential value, the denial of CEH’s request for an injunction can be used as persuasive authority for other courts adjudicating similar issues related to the premature substitution of unleaded fuel for 100LL aviation fuel. Judge Chatterjee’s denial of CEH’s injunction request is reminiscent of another case, Boomer v. Atlantic Cement, where an injunction was sought by aggrieved plaintiffs, but denied by the Court for a confluence of reasons.[12]
In Boomer v. Atlantic Cement, the plaintiffs sought an injunction from the Court to prohibit the defendant cement plant from operating. The cement plant’s operations were causing the discharge of particulate matter into the atmosphere which landed on the plaintiffs’ real property. The plaintiffs alleged and proved harm from the cement plant’s effluent discharge. Under New York law, the plaintiffs were entitled to an injunction based on the seminal case of Whalen v. Union Paper Bag & Co.[13] Boomer is worthy of comparison to the CEH case because the injunction against the operation of the cement plant was denied in large part due to the adjudication of (i) the negative impact that closure of the cement plant’s impact on the local economy would have caused combined with (ii) the inability of the stand-alone cement plant to rectify the continuing pollution aspect of the plaintiff’s harm. The similarities in the reasoning set forth in Boomer and in Judge Chatterjee’s CEH order deserve review.
There are three key similarities that merit comparing the CEH outcome with Boomer v. Atlantic Cement. Both cases involved alleged environmental harm. The plaintiffs in Boomer alleged harm from particulate matter in the effluent discharge from the cement plant’s operations. The plaintiff in CEH alleged harm to the environment from the presence and spread of lead in aviation fuel. Next, the relief sought in both cases required the court to exercise its equitable powers. Finally, the resolution to the injury causing event involved a larger group of stakeholders with economic complexities beyond the parties before the court. Focusing on the larger group of stakeholders needed to resolve the problem and the recognition of the economic complexities gives Judge Chatterjee’s order significance, making it ripe for reliance in future cases as persuasive authority.
In Boomer, the court recognized that the process of making cement resulted in the harmful discharge of particulate matter into the atmosphere.[14] In CEH, the plaintiffs requested an injunction mandating the use of unleaded aviation fuel to eradicate the impact of lead toxins in the ground surrounding the airports. In both cases, the courts recognized that the operations causing the harm were not endemic to the individual defendants, but instead were industry-wide problems shared by similarly situated people and entities nationally, requiring additional stakeholders’ involvement to resolve the root cause of the problem.
With respect to the transition to an unleaded aviation fuel, the regulatory authority and the industry stakeholders are working on the complexities of the problem to obtain a solution. In Boomer, the court recognized that the goal of eliminating harmful effluent from cement plant operations rested with the industry and not just the cement plant before the Court. With full recognition of this truth, the court in Boomer declined to issue an injunction because it reasoned that the exercise of the court’s injunctive powers would have supplanted the policymakers’ powers to create policy and accompanying legislation. A balance needed to be reached by policymakers and not the court to achieve both (i) particulate matter free cement plant operations to protect the environment, and (ii) economically sustainable cement plant operations that contributed tax revenue and employment to the local community. The FAA established the Eliminate Aviation Gasoline Lead Initiative (EAGLE), which is a government and industry cooperative established to address the transition from the use of leaded to unleaded aviation gas.[15] Judge Chatterjee’s order reached the same conclusion, “Courts in general should be careful to avoid assuming general regulatory powers and determining complex economic policies.”[16]
Conclusion
The Santa Clara County decision issued by the FAA identified a breach of contractual obligations owed because the County accepted federal money to operate its two public use airports under certain conditions. In this instance, the Grant Assurance required the airport sponsor to provide leaded fuel for sale and use at its airports. As a result, the County was ordered to resume making 100LL fuel available. Industry stakeholders emphasized the negative repercussions on safety and the negative economic impacts on general aviation businesses utilizing piston powered aircraft that require 100LL fuel. In CEH, the court reached the conclusion that the exercise of its equitable powers was unwarranted because there was not yet a commercially available drop-in unleaded fuel replacement for leaded aviation gas. The Court relied in large part on the regulatory and industry cooperative efforts to eliminate the use of leaded aviation gas by 2030 in reaching its decision. Collectively, the FAA’s decision with the Alameda County Court’s order signals that the rush to remove leaded aviation gas was rejected because of the deleterious effects on the industry that would jeopardize safety, and the economy at large. A process under the purview of the FAA is in place to remove leaded aviation fuel from use. Patience and collaboration with the regulatory authorities and industry is necessary to be successful in finding and implementing a drop-in replacement for 100LL fuel.
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Ronnie R. Gipson Jr. is an Associate Professor at Penn State Dickinson Law. Ronnie’s scholarship on aviation law issues is published worldwide and his work also appears in the Congressional record of the U.S. House of Representatives. He also serves as the Chair of the EAA Legal Advisory Council.
[1] Aircraft Owners, and Pilots Association, et al., v. County of Santa Clara, California, FAA Docket No. 16-22-08, Director’s Determination (Mar. 24, 2025).
[2] See Center of Environmental Health v. Aerodynamic Aviation, RG11600721, Alameda County Superior Court, (May 30, 2025).
[3] When a public use airport receives money in the form of a grant from the federal government the transfer and use of the funds is done so with conditions that the airport sponsor must meet. These conditions are referred to as grant assurances. See FAA Airports—Assurances Airport Sponsors, https://www.faa.gov/airports/aip/grant_assurances/assurances-airport-sponsors
[4] The FAA also found that the County violated other grant assurances which will not be discussed in this article.
[5] The Airport Improvement Program (AIP) provides grants to public agencies — and, in some cases, to private owners and entities — for the planning and development of public-use airports that are included in the National Plan of Integrated Airport Systems (NPIAS). See Federal Aviation Administration, Airport Improvement Program, https://www.faa.gov/airports/aip (accessed Aug. 16, 2025); 49 U.S.C. § 47107 (a) 2025.
[6] The Airport Improvement Program (AIP) is a federal grant program managed by the Federal Aviation Administration (FAA) that provides funding for the planning and development of public-use airports in the United States. These grants help airports enhance safety, increase capacity, mitigate noise, and maintain infrastructure. See https://www.faa.gov/airports/aip.
[7] Center for Environmental Health v. Aerodynamic Aviation, et al., Alameda County Superior Court Case No. RG11600721, Order Denying Motion of CEH to Enforce and Modify Consent Judgment (May 30, 2025).
[8] Jim Moore, Final Ruling Preserves Avgas Availability in California, AOPA (June 5, 2025). https://www.aopa.org/news-and-media/all-news/2025/june/05/final-ruling-preserves-avgas-availability-in-california
[9] The erosion of fuel tank sealants in an aircraft brings the airworthiness of the airframe into question requiring costly inspections and accompanying repairs.
[10] Mark Anderson, What are ASTM Standards and Why Do They Matter?, Mar. 13, 2024. ASTM approves aviation parts for compliance with international standards
[11] Cal. R. Ct. 8.1115 (2025).
[12] Boomer v. Atlantic Cement, 257 N.E.2d 870 (N.Y. 1970).
[13] Whalen v. Union Paper Bag & Co. , 208 N.Y. 1 (N.Y. 1913).
[14] Boomer, supra, note 12.
[15] Federal Aviation Administration, Building an Unleaded Future by 2030, https://www.faa.gov/unleaded.
[16] CEH, supra, note 7, p. 12.
