Updates

WASHINGTON – The Federal Aviation Administration (FAA) and the public-private Eliminate Aviation Gasoline Lead Emissions (EAGLE) initiative are calling on pilots, aircraft owners, mechanics, and fixed-base operators (FBOs) to help shape the future of general aviation by documenting and reporting their experiences with the use of a new, high-octane unleaded aviation fuel available at various airports across our Nation.

As the transition away from leaded avgas accelerates, real-world feedback is critical to ensuring the safe and efficient operation of piston-engine aircraft across the general aviation fleet. The FAA has issued a new Special Airworthiness Information Bulletin (SAIB 2025-04) to request voluntary reports on service or flight difficulties—or smooth operations—when using FAA-authorized unleaded fuel alternatives. The SAIB instructs submittal of these voluntary reports to [email protected] with “Unleaded Fuel” in the subject line.

It’s critical for pilots and aircraft owners to respond to SAIBs because they inform critical safety recommendations that can help prevent incidents and mechanical failures. While not mandatory, addressing the issues highlighted by SAIBs, especially for new products, supports this effort and helps ensure continued airworthiness.

“Pilots, owners, maintainers and FBOs across the country are on the front lines of the shift to unleaded fuel,” says EAGLE’s cochair Curt Castagna.  “These experiences and reports are essential to validating safe alternatives and identifying potential challenges early. We urge everyone flying or servicing aircraft on unleaded avgas to share their experiences—it’s how we ensure a smooth and successful transition for the entire industry.”

SAIB 2025-04 outlines specific details the FAA is interested in gathering, including aircraft and engine information, fuel type used, maintenance history, any observed issues, and even documentation like photos or fuel samples.

Importantly, the FAA is also encouraging submissions from operators who have transitioned to unleaded fuel with no issues.

“The FAA is committed to a safe transition to unleaded avgas,” adds Caitlin Locke, FAA’s EAGLE cochair. “The reports we receive will directly inform our oversight, help us distinguish between unrelated mechanical issues and fuel-related concerns, and ultimately support the safe shift of the piston-engine aviation fuel supply.”

For full details on what to report and how, view the full Special Airworthiness Information Bulletin SAIB 2025-04.

####

Eliminate Aviation Gasoline Lead Emissions (EAGLE) is a comprehensive government-industry initiative consisting of the aviation and petroleum industries and U.S. government stakeholders, and a wide range of other constituents and interested parties, all working toward the transition to lead-free aviation fuels for piston-engine aircraft by the end of 2030 without compromising the safety or economic health of the general aviation industry. To learn more, visit: https://flyEAGLE.org.

In this final article, Eliminate Aviation Gasoline Lead Emissions (EAGLE) provides information on the critical role of industry consensus standards, such as those from ASTM International, to assist in the safe and consistent production, distribution, and use of aviation fuels.

Q: Why is a consensus-based specification for a new unleaded aviation fuel important to pilots and aircraft owners?
A consensus-based specification for a new unleaded aviation fuel undergoes a rigorous peer review of the required properties for the fuel and an assessment of which test procedures must be applied to determine if the fuel meets the requirements for its intended purpose. The specification is a governing document that is used to assess the quality of the fuel and provides assurances that it will perform in the aircraft as expected regardless of where the fuel is purchased. Industry consensus standards are developed by entities who bring together representatives and experts in a given field and provide the framework to develop proposed standards with appropriate supporting data which is then reviewed, discussed, questioned, and ultimately agreed upon by reaching consensus. If consensus is not reached, the issues are adjudicated through an established process with all members of the group having the opportunity to weigh in on the outcome.

Additionally, the consensus standards development process facilitates the understanding and acceptance of a fuel across a broad range of aviation and petroleum stakeholders.  During the development of the standard, and by reaching consensus, issues (beyond those of airworthiness considered by the FAA as part of an applicants’ STC application) are surfaced and addressed by the fuel sponsors. Examples include questions about the fuel’s fit for purpose, fuel handling and storage characteristics, and cosmetic impacts on aircraft that may not affect airworthiness but are of interest to manufacturers, maintainers, and aircraft owners.

Q: Why are consensus standards important to aviation as a whole?
Consensus standards help provide consistency in fuel quality and compatibility with existing infrastructure, facilitating a smooth transition to lead-free aviation gasoline.

There are several stakeholder organizations directly involved in making the business and financial decisions to take on the responsibility and risks of deploying a brand-new fuel. This includes decisions to produce the new fuel by bringing together petroleum and some new chemical components per the fuel production specification; distribute the new fuel by transporting via road, rail and barge infrastructure; store the new fuel at various transportation connection locations and airports; dispense the new fuel into customer GA aircraft ensuring safety and compliance for aircraft and personnel; and provide maintenance and manufacturer continued operational safety, technical and warranty support. These are marketplace decisions that must be made by several different stakeholder businesses that are not related to FAA issuance of a TC, STC, authorization or any other approval. Just as FAA must have the information necessary to determine compliance with 14CFR part 23 airplane and part 33 engine airworthiness requirements to make its approval decision, producers, distributors, fixed base operators (FBOs), airports, and engine/aircraft manufacturers require an adequate understanding of a new fuel to make business decisions on the risks of deployment.

Without consensus standards, each company in the supply chain would need to individually review testing data and the specifications derived from that data. This approach is costly, time-consuming, and lacks the benefits of broad industry subject matter expert peer review, input, and oversight.

A successful transition to a new unleaded fuel requires broad acceptance across the aviation and petroleum industries, relying on rigorous testing, stakeholder collaboration, and the establishment of robust specifications.

Q: How do industry consensus standards assist in fuel safety and reliability throughout production and distribution?
Fuel production, distribution, storage, and handling parameters are set by multiple consensus standards developed by a thorough analysis by leading experts. These standards, along with industry-supported consensus specifications, provide confidence in the fuel’s composition, properties, and quality throughout production, distribution, and delivery to the aircraft.

New fuels must be tested not only for engine compatibility but also for their interactions with materials used throughout the supply chain, including hoses, filters, gaskets, and other fuel system components. Materials compatibility evaluation serves as due diligence in helping to ensure that fuels do not degrade or contaminate equipment used in transportation and storage.

Consensus standards can help minimize risks for pilots, aircraft owners, airports, fuel distributors, and fixed-base operators (FBOs), and help to ensure that unleaded aviation fuels maintain their integrity from manufacture to aircraft. They also provide a framework for mitigating operational risks, so that new fuels can be used safely in both existing and newly developed fueling infrastructures.

Q: Who is ASTM International, and what role do they play in the introduction of new unleaded aviation fuels?
ASTM International, an independent, non-government organization, is a globally recognized standards development body that establishes and manages technical specifications for a wide range of products, including aviation fuels. Founded in 1898, ASTM brings together experts from various industries to create and maintain standards that ensure product quality, safety, and performance. In aviation, ASTM plays a key role in developing voluntary consensus standards for aviation fuels, including unleaded avgas, as well as motor gasoline, diesel fuel, jet fuel, and biofuels.

The ASTM standard development process is a collaborative effort that includes developers, refiners, manufacturers, aircraft and engine producers, distributors, equipment makers, providers, and users. The process provides opportunities for chemists and engineers to review the data that supports either modifications to an existing standard or the development of a newly proposed standard. The review process allows for challenges to be raised and discussions to be held, facilitating the development of a standard that is relevant and technically sound with regards to fuel production, performance characteristics, and compatibility with existing aircraft and the fuel distribution infrastructure. These rigorous assessments are there so that, if the final specification is met, they will promote safe production of the fuel.

For pilots and aircraft owners, an ASTM fuel production specification —“ASTM spec”— provides assurances that modifications to an existing spec or to a proposed unleaded fuel specification have been rigorously reviewed in the context that it can be consistently manufactured and supplied to the end user. ASTM specs also help maintain fuel consistency, reduce potential maintenance issues, and protect aircraft engines from incompatibility concerns.

Q: Where else is an ASTM specification found?
Just about every fuel available for purchase today—even outside aviation—has an ASTM specification, including:

• automobile gasoline and ethanol
• truck diesel and biodiesel
• home heating oil
• kerosene
• jet fuel
• 100LL Avgas
• UL94 Avgas
• UL91 Avgas

Further, many regulatory bodies incorporate ASTM standards by reference. Read the ASTM D910-21 Standard Specification for Leaded Aviation Gasolines here.

Q: Does using the consensus standard process take longer than developing a producer developed standard?
The consensus process provides data and understanding about a fuel’s composition, performance and other important properties and specific test methods to measure those properties for peer review among subject matter experts in fuels, chemistry, test methods, production, distribution, aviation manufacturers and end users. This peer review process, combined with the ability for any stakeholder to ask questions and review additional data, provides interested stakeholders an understanding of a brand-new fuel. It also provides the opportunity to express confidence and acceptance through a voting process to adopt a new fuel production specification.

A consensus standard can take longer to complete than a producer-developed standard. There are multiple reasons for this, including:

• The time it takes to develop a successful standard is determined largely by the sponsor’s ability to supply appropriate data to support their proposed standard and how thorough and responsive they are to addressing questions and issues raised through the balloting process.
• Consensus requires an open and transparent discussion of the data that supports the proposed change to an existing standard or a newly proposed standard.
• There is an adjudication process that allows an individual to raise a concern for consideration by the entire body of volunteers. If the concern is deemed relevant, it must be addressed to the satisfaction of the consensus body.

Eliminate Aviation Gasoline Lead Emissions (EAGLE) is a comprehensive government-industry initiative consisting of the aviation and petroleum industries and U.S. government stakeholders, and a wide range of other constituents and interested parties, all working toward the transition to lead-free aviation fuels for piston-engine aircraft by the end of 2030 without compromising the safety or economic health of the general aviation industry. To learn more, visit: https://flyEAGLE.org.

This is the second installment in a three-part series explaining how the next generation of unleaded aviation fuels may be authorized for use in specific engines and aircraft. This segment focuses on the FAA’s Fleet Authorization process, developed utilizing the Piston Aviation Fuels Initiative (PAFI) along with the use of ASTM standards. The first installment (see Dec 2024 update below) covered Supplemental Type Certificates (STC) and Approved Model List STCs (AML STCs). The final installment will discuss the critical role of industry consensus standards, such as those from ASTM International, in ensuring the safe and consistent production, distribution, and use of aviation fuels.

Q: What is the FAA Fleet Authorization process, and why is it important to pilots and aircraft owners?
Pilots and aircraft owners should be aware that the Fleet Authorization process will result in the FAA, through PAFI, authorizing a qualified unleaded fuel for use in aircraft and aircraft engines. The makes and models of type certified and non-type certificated piston aircraft and aircraft engines that can safely operate with the qualified unleaded avgas will be compiled and published by the FAA in a document called the Eligible Fleet Authorization Summary Report (EFASR). EAGLE highlighted the FAA’s Fleet Authorization process in a recent Fact Sheet.

Q: How does the Fleet Authorization process work?
Under the Fleet Authorization process, the FAA collaborates with industry partners to conduct comprehensive testing of candidate unleaded fuels. This includes evaluating the fuel’s compatibility with various aircraft materials, engines, operational environments, and supply chain components. This data, along with an approved ASTM production specification, is required for a qualified replacement fuel. Once it is qualified and the EFASR is published, the FAA will issue a Special Airworthiness Information Bulletin (SAIB) which will “identify the qualified fuel, specify the aircraft and engines eligible to use
the qualified fuel, and provide references and other information to accomplish the alteration necessary to enable the use of the fuel.” It should also be noted that type certificate applicants and holders, as well as owners/operators of non-type certificated piston-powered aircraft, may refer to the
EFASR and SAIB to determine whether the fuel can be safely used with their aircraft and engines. Owners of Special Light Sport Aircraft (SLSA) can also use the information provided to meet the operating limitations specified in 14 CFR §91.327(b)(5).

Q: What role does PAFI play in the Fleet Authorization process?
PAFI, or the Piston Aviation Fuels Initiative, is a collaboration between the FAA, industry stakeholders, and technical experts to identify and evaluate unleaded fuel candidates. Established in 2014, PAFI defines and executes comprehensive testing protocols to ensure that candidate fuels meet necessary safety, performance, and environmental standards. PAFI is required by the FAA to make fleet-wide authorization decisions, and it generates the technical data required to support the ASTM specification. Then, this data undergoes extensive peer review by aviation and fuel experts involved in avgas  production, distribution, storage, dispensing, operation, maintenance, and aircraft usage to ensure the fuel’s safety and reliability. The resulting data helps the marketplace determine whether approved fuels are viable not only for aircraft operation but also for long-term production and distribution.

Q: How does the Fleet Authorization process compare to the STC process?
While both the Fleet Authorization and STC processes aim to ensure safe fuel use, they differ significantly in scope and application: STC Process: The STC process requires FAA approval for each aircraft and aircraft engine model. In the STC process, fuel developers work directly with the FAA to conduct
required testing to collect data proving compatibility, safety, and performance for specific engines and airframes. This data is provided to the FAA for evaluation, determination of means of compliance, and authorization to approve the unleaded fuel for the requested aircraft and engines. Aircraft and engines each require their own STC. Once the fuel is authorized by the FAA, aircraft owners must then purchase the approved STC and work with a certificated mechanic to implement the required modifications. Fleet Authorization Process: As stated above, the FAA, through PAFI, collaborates with
industry partners to conduct comprehensive testing of candidate unleaded fuels. This includes evaluating the fuel’s compatibility with various aircraft materials, engines, operational environments, and supply chain components. This data, along with an approved ASTM production specification for the unleaded fuel, is required to have a qualified replacement fuel. Once there is a qualified replacement fuel and the EFASR is published, the FAA will issue a SAIB which will “identify the qualified fuel, specify the aircraft and engines eligible to use the qualified fuel, and provide references and other information to accomplish the alteration necessary to enable the use of the fuel.” This process may also require engine and other modifications to the aircraft.

Q: Is there information available regarding the PAFI test plans, including engines, airframes, and materials that will be tested?
Yes, this information is available at: https://flyeagle.org/resources/

Stay tuned for Part 3, where we will explore the role of industry consensus standards, such as those from ASTM International, in ensuring the safe, consistent production, distribution, and use of unleaded aviation fuels.

Eliminate Aviation Gasoline Lead Emissions (EAGLE) is a comprehensive government-industry initiative involving the aviation and petroleum industries, U.S. government stakeholders, and a wide range of other constituents and interested parties. Together, they are working toward the transition to lead-free aviation fuels for piston-engine aircraft by the end of 2030, without compromising the safety or economic health of the general aviation industry. To learn more, visit: https://flyEAGLE.org.

This is the first in a three-part series explaining how the next generation of unleaded aviation fuels may be authorized for use in specific engines and aircraft. This installment examines the Type Certificate (TC) and Supplemental Type Certificate (STC) processes, which enable eligible aircraft and engines to operate using qualified unleaded aviation gasoline (avgas) under the FAA’s traditional certification procedures. The second part will review the Fleet Authorization process, developed through the Piston Aviation Fuels Initiative (PAFI), which allows eligible aircraft and engines to operate safely using unleaded avgas. The final installment will discuss the importance of industry consensus standards, such as those from ASTM International, in ensuring the safe, consistent production, distribution, and use of aviation fuels. For more information on
these topics, visit: https://flyEAGLE.org.  

Q: Why should pilots and aircraft owners be invested in the unleaded avgas approval process?
Pilots and aircraft owners play a critical role in the transition to unleaded fuels. Staying informed ensures they can adopt new fuels safely and efficiently while maintaining compliance with the required approvals or authorizations.

While the approval processes may seem technical, they directly affect daily operations, safety, maintenance, and long-term aircraft reliability. By understanding these impacts, owners can confidently navigate the transition and make informed decisions for their aircraft and missions.

Q: What is an STC, and how is it used to authorize unleaded aviation fuel for specific aircraft and engines?
A Supplemental Type Certificate (STC) is an FAA-issued approval that authorizes the use of specific fuel, fluids, parts, and/or equipment in a designated list of aircraft and engines. It is one of two pathways fuel developers can use to bring their products to market.

Through the STC process, fuel developers are solely responsible for testing the compatibility, safety, and performance of a new fuel with specific aircraft and engine models. Once the FAA reviews and approves the data, an STC is issued, authorizing the use of the fuel. The STC database can be searched to identify aircraft models approved for a specific modification or installation.

The applicant can sell the STC to customers, enabling them to modify their individual aircraft for the use of the fuel specified in the STC. This modification typically includes updating the fuel placard and may require additional adjustments depending on the STC. For aircraft with a standard airworthiness certificate, the alteration must be performed by a certificated mechanic or authorized entity in compliance with the STC.

STC data is considered proprietary to the applicant. Therefore, the FAA does not provide STC data directly to owners of aircraft with special, restricted, or experimental airworthiness certificates. However, the applicant may choose to share the necessary information with interested parties. Owners of Special Light Sport Aircraft (SLSA) can implement the authorization after the SLSA manufacturer issues approval. Experimental aircraft owners must individually determine appropriate unleaded fuels, either by conducting their own compatibility assessments or consulting the STC holder for relevant data.

Q: What is the Approved Model List (AML)?
The AML is a list of aircraft models approved for a specific modification or installation, typically under a Supplemental Type Certificate (STC). Aircraft owners must take specific actions to implement changes to their aircraft, typically through Service Bulletins or the installation of an STC. For aircraft with a standard airworthiness certificate, the alteration must be performed by a certificated mechanic or authorized entity in compliance with the TC/STC.

Q: How does the STC process differ from the FAA fleet authorization process?
Under the FAA’s traditional STC/AML process, an applicant is responsible for demonstrating that the aircraft and engines meet all applicable regulations and minimum standards under the normal certification process when using the new unleaded fuel. The FAA reviews the compliance data provided by the applicant and, upon approval, issues an STC.

Under the Piston Aviation Fuels Initiative (PAFI), the FAA uses a combination of testing and analysis methods developed in collaboration with industry to determine if an unleaded avgas qualifies as a replacement for approved leaded avgas. The data obtained through testing supports the development of the ASTM production specification for the candidate fuel.

The FAA will identify the makes and models of type-certificated and non-type-certificated piston aircraft and engines that can safely operate with the qualified unleaded avgas, compiling them in the Eligible Fleet Authorization Summary Report (EFASR), which will also include experimental aircraft.

Additionally, the FAA will issue a Special Airworthiness Information Bulletin (SAIB) and provide detailed instructions to implement the necessary alterations for using the fuel. The candidate fuel is then qualified as a replacement fuel under the fleet authorization process for the eligible portion of the fleet.

Q: Why is it important for pilots and aircraft owners to read and understand an unleaded fuel STC?
It’s crucial for pilots and aircraft owners to read and fully understand an STC, as it outlines the specific modifications, limitations, and operational requirements necessary to safely integrate the approved fuel or equipment into their aircraft. Strict adherence to the STC ensures compliance with FAA regulations while maintaining the safety, reliability, and airworthiness of the aircraft. Currently two fuels, G100UL from General Aviation Modifications, Inc. (GAMI) and Swift Fuels’ 100R have approved AML-STCs.

By understanding both pathways, pilots and owners can better plan for the transition to unleaded fuels. Whether through individual STCs or fleet-wide approvals, these processes are designed to ensure safety and reliability.

Part 2 of this three-part series will delve into the FAA Fleet Authorization process and its benefits for the general aviation community.

Eliminate Aviation Gasoline Lead Emissions (EAGLE) is a comprehensive government-industry initiative consisting of the aviation and petroleum industries and U.S. government stakeholders, and a wide range of other constituents and interested parties, all working toward the transition to lead-free aviation fuels for piston-engine aircraft by the end of 2030 without compromising the safety or economic health of the general aviation industry. To learn more, visit: https://flyEAGLE.org

NASA’s Aviation Safety Reporting System (ASRS) has amended a report (December 2024 CALLBACK) that incorrectly attributed deterioration of cadmium-plated bolts in an aircraft’s fuel system to an approved aviation gasoline unleaded fuel, Swift Fuels’ UL94. It was later discovered that the actual cause was auto gas (mogas) and an isolated incident.

In April 2023, an aviation maintenance technician providing service to a fixed base operator (FBO) for a flight school reported that damage to cadmium-plated bolts, commonly used in aircraft carburetors, had been caused by UL94. UL94 is an unleaded fuel approved by an FAA STC, with an ASTM specification, and that supports a majority of the nation’s piston fleet. Swift is one of three fuel companies currently working with the FAA to develop a replacement fuel (Swift 100R). It is a candidate to support additional piston aircraft in the fleet as the industry’s current leaded aviation fuel is to be phased out by the end of December 2030.

After further investigation by the FAA, it was determined that auto gas (mogas) caused the issues and was an isolated incident. The amended CALLBACK report clarified that the damage to the cadmium parts was not caused by UL94.

The EAGLE initiative released the following statement to further clarify the issue:

“A recent NASA ASRS CALLBACK report noted a potential issue in 2023 between UL94 aviation fuel and cadmium components. The FAA received the same information in 2023 concerning this issue, prompting an investigation. At this time, the FAA investigation determined that the fuel in question was not UL94, but mogas from a local gas station. No incompatibility has been identified between UL94 and cadmium components.”

EAGLE urges pilots and aircraft owners to stay vigilant to prevent misfuelling incidents and be mindful of any STC or other POH limitations on mixing aviation fuel. More information on how to avoid misfuelling can be found in the November 2024 EAGLE update titled “Pilots & Aircraft Owners: Stay Vigilant as New Unleaded Aviation Fuels Roll Out” https://flyEAGLE.org/updates/.

Eliminate Aviation Gasoline Lead Emissions (EAGLE) is a comprehensive government-industry initiative consisting of the aviation and petroleum industries and U.S. government stakeholders, and a wide range of other constituents and interested parties, all working toward the transition to lead-free aviation fuels for piston-engine aircraft by the end of 2030 without compromising the safety or economic health of the general aviation industry. To learn more, visit: https://flyEAGLE.org

For more information on the transition to unleaded aviation fuel, visit: https://flyEAGLE.org

The growing availability of unleaded aviation fuel represents a crucial step toward eliminating lead emissions from aircraft. However, it also introduces new misfueling risks that occur when the wrong type, grade, or mix of fuel is delivered to an aircraft. With multiple fuel options now available, pilots, aircraft owners and line service personnel must be more vigilant than ever to ensure fueling safety.

Misfueling can lead to catastrophic engine failure, which is why clear communication between pilots and line service personnel is essential.

Pilots should confirm the limitations of the engine and airframe. And, when placing full-service fuel orders, confirm every detail of the order—including type, grade, and volume—with line service personnel, or be aware of these factors when conducting self-service fueling.  Aircraft must also have proper logbook documentation and placards installed.

It is important to note that while the new unleaded fuels are designed to mix with 100LL, it remains uncertain whether they can be safely mixed with each other. Until more information is available, unleaded fuels must not be combined. Again, each engine and/or aircraft may have specific limitations that aircraft owners need to be aware of when fueling their aircraft.

Resources such as the Energy Institute’s Misfuelling Resources, AOPA’s Safety Brief, the National Air Transportation Association’s (NATA) Misfueling Prevention Program, and the EAGLE’s Guidance on Transitioning a Flight School to Unleaded Avgas offer valuable guidance during this transition. As unleaded fuels become more widely available, diligence and adherence to proper protocols will be essential to maintaining safety and protecting your aircraft.

Eliminate Aviation Gasoline Lead Emissions (EAGLE) is a comprehensive government-industry initiative consisting of the aviation and petroleum industries and U.S. government stakeholders, and a wide range of other constituents and interested parties, all working toward the transition to lead-free aviation fuels for piston-engine aircraft by the end of 2030 without compromising the safety or economic health of the general aviation industry. To learn more, visit: https://flyEAGLE.org

The aviation community has long recognized the need to eliminate lead emissions from piston-engine aircraft, a goal set to be achieved by the end of 2030 through the leadership of the Eliminate Aviation Gasoline Lead Emissions (EAGLE) initiative. This ambitious endeavor brings together government and industry partners committed to finding a safe and reliable unleaded aviation fuel that is viable throughout the aviation supply chain.

As the general aviation community works toward this goal, the role of aircraft owners cannot be overstated. They are, after all, the ultimate end-users of any new fuel, and their buy-in will be critical to its success.

This transition is about more than meeting regulatory requirements—it’s about ensuring that aircraft owners feel confident in the safety and reliability and availability of the new fuel. The solution must be robust enough to meet the diverse needs of the piston-engine fleet, ranging from the World War II era planes to modern helicopters.

Currently, there are three promising unleaded fuel candidates. Their developers are pursuing either the Fleet Authorization (FA) under the Piston Aviation Fuels Initiative (PAFI) or the traditional Supplemental Type Certification (STC) process via an approved model list (AML). Both pathways ensure that engines and aircraft can safely operate on the new fuel, however, regardless of the path to approval to use in the aircraft, consumer acceptance will hinge on more than FAA approval.

Fuel developers must not only prove their products’ safety and compatibility with the existing fleet but also demonstrate to key industry stakeholders that their product is reliable. Aircraft owners need assurance that switching to a new fuel won’t void manufacturer warranties. They also need to be confident that it won’t cause damage to paint, electronics, engine components or fuel systems. The aviation supply chain will need assurances as well. This next fuel must be produced, distributed, stored, possibly comingled with other fuels, pumped, and consumed without causing damage or requiring significant equipment modifications. Industry stakeholders understand that any new fuels must meet the needs of aircraft owners and be compatible with production, distribution and dispensing systems.

EAGLE has worked diligently over the past 18 months to keep stakeholders informed, providing updates on the progress of key unleaded fuel developers. General Aviation Modifications Inc.’s (GAMI) G100UL and Swift Fuels’ 100R are advancing through the STC process. GAMI has already secured a broad Approved Model List (AML) STC for its fuel in 2022 for piston engines and airplanes. Recently, the FAA granted Swift Fuels its first STC for the use of its 100R in Cessna 172 R & S model aircraft powered by Lycoming IO-360-L2A engines, with many additional engines and airframes being evaluated for approval in the weeks ahead. LyondellBasell/VP Racing’s UL100E is progressing through the PAFI pathway, having completed about 25 percent of critical materials compatibility and full-scale engine detonation and performance testing. Both Swift Fuels and LyondellBasell/VP Racing have also begun working through ASTM International on the development of an industry consensus production specification for their respective fuels.

The recent updates from EAGLE provide optimism. To learn more visit: flyEAGLE.org (See Stakeholder Meetings). Progress is being made, and general aviation’s path to acceptance of unleaded fuel continues.

Congress and the FAA’s commitment to this initiative is underscored by the 2024 FAA Reauthorization, which supports the continued availability of 100-octane low-lead (100LL) avgas until the end of 2030, or when a certified unleaded alternative is available at airports. (Alaska, a state heavily reliant on piston-engine aircraft, has been given a slightly extended timeline protecting continued availability of 100LL through the end of 2032). However, the collaborative industry/government EAGLE goal is clear: the elimination of leaded aviation fuel by the end of 2030.

General aviation is moving to ensure a safe, reliable transition to unleaded avgas without jeopardizing the operational safety of the piston-engine fleet. Aircraft owners must stay informed and engaged as this transition unfolds. It is important that they educate themselves on any restrictions that may accompany an STC and comply with any OEM directives that may be issued. They are the key players in this process, and their comfort with these new fuels will drive this monumental shift.

It is not enough for the FAA to approve these new fuels. The industry—from aircraft owners to fuel distributors to FBOs that dispense fuel and aircraft manufacturers that provide continued operational support—must accept them. Safety, reliability, and commercial viability must guide this transition, ensuring that by the end of 2030, piston-engine aircraft can take to the skies with unleaded fuel that is dependable. The future of general aviation depends on it.

Eliminate Aviation Gasoline Lead Emissions (EAGLE) is a government-industry initiative consisting of the aviation and petroleum industries and U.S. government stakeholders, and a wide range of other constituents and interested parties, all working toward the transition to lead-free aviation fuels for piston-engine aircraft by the end of 2030 without compromising the safety or economic health of the general aviation industry. To learn more, visit: https://flyEAGLE.org