Learn More About Lycoming’s Efforts Around Unleaded Fuels
Lycoming remains committed to finding a comprehensive fuel solution that will allow a fleet-wide transition to lead-free aviation fuels for piston-engine aircraft
Lycoming Engines has been producing piston aviation engines for over 95 years, and we “build every engine as though we were going to fly it ourself!” Safety is an utmost priority, and we strongly support efforts to eliminate lead from aviation fuels. For this reason, Lycoming has been researching fuels for decades and is an industry leader in the Piston Aviation Fuels Initiative (PAFI) and the Eliminate Aviation Gasoline Lead Emissions (EAGLE) initiative.
As a result of these pathbreaking efforts, Lycoming has approved several unleaded fuels for use in Lycoming Engines.
Please reference our Service Instruction 1070 for approved fuels for our aircraft engine models.
Through our progress, we remain committed to finding a comprehensive fuel solution that will allow a fleet-wide transition to lead-free aviation fuels for piston-engine aircraft that does not compromise the safety or economic health of the general aviation industry. We take our work seriously to keep our fleet safe, and our approvals process for new fuels follows strict FAA and industry standards and guidelines. This process includes both the evaluation of how fuels will perform in our engines and options for improving the design of our products to work with commercially available unleaded fuels.
Lycoming will continue to strive to support a future unleaded fleet while working to ensure that our products remain safe and reliable.
Q: What is PAFI?
A: The Piston Engine Aviation Fuels Initiative (PAFI) program was established in 2014 to support the evaluation of candidate-unleaded fuels to replace approved leaded gasoline, with the objective of ultimately qualifying a fleet-wide solution.
To learn more about PAFI, visit their website at www.faa.gov.
Q: What is the EAGLE initiative?
A: According to their website, Eliminate Aviation Gasoline Lead Emissions (EAGLE) is a broad and collaborative initiative among the Federal Aviation Administration (FAA), the general aviation (GA) community, fuel suppliers and distributors, airports, engine and aircraft manufacturers, research institutions, associations, local communities, environmental groups and other key stakeholders. EAGLE partners are committed to ensuring the GA sector can safely transition to a lead-free future by the end of 2030 (at the latest) without affecting the safe and efficient operation of the piston-engine fleet. EAGLE's initiative has four pillars: address the unleaded fuel evaluation and authorization; research, development, and innovation; supply chain infrastructure and deployment; and regulation policy and programmatic activities.
To learn more about EAGLE, visit their website at www.flyeagle.org.
Q: How are PAFI and EAGLE different?
A: PAFI was established in 2014 to support the evaluation of candidate-unleaded fuels to replace approved leaded gasoline, with the objective of ultimately qualifying a fleet-wide solution. Once a candidate fuel formulation is qualified for PAFI testing, the FAA tests it using methods created through collaboration with industry. In 2022, the FAA and industry groups (GAMA, AOPA, etc) recognized a need to implement a comprehensive cross-sector approach to safely eliminate leaded aviation fuel by the end of 2030 without impacting the safe and efficient operation of the piston-engine fleet. PAFI became an integral part of one of the four critical EAGLE pillars tasked with evaluation and authorization of the unleaded fuel (UL).
In addition to PAFI, EAGLE recognizes that the FAA has allowed an alternative pathway for unleaded fuels to become approved via the traditional Supplemental Type Certificate (STC) process.
Q: Why is Lycoming a proponent of PAFI versus STC?
A: Fuel manufacturers can pursue approval either via PAFI or through a traditional aftermarket STC process. As an OEM, Lycoming is committed to supporting PAFI because it provides for a holistic evaluation of the candidate fuels through the collaboration of government and industry partners. This evaluation includes material compatibility, evaluation of toxicity, engine testing for detonation, endurance, flight testing and operability; as well as review of operational concerns to determine that a fuel is fit-for-purpose. Safety is of utmost importance, and Lycoming wants to align with the collective industry expertise. Upon final testing, PAFI allows for the FAA administrator to grant fleet-wide approval for fuel.
Alternatively, Type Certificate (TC) holders like Lycoming do not typically support the STC process, and there is no FAA guidance or established industry process for a TC holder to evaluate an STC candidate fuel. Instead, a fuel manufacturer applying for a STC works directly with the FAA and without the benefit of TC holders like Lycoming. Often TC holders are not provided critical technical information that they would need to determine if the candidate fuel is safe. As a result, per 14 CFR 21.115, the STC holder is ultimately and exclusively responsible for demonstrating that its fuel meets the FAA’s airworthiness requirements.
Because Lycoming believes that the flying public is best served by a transparent, collaborative, documented, and cross-industry process to ensure that each candidate fuel is safe, we urge each candidate fuel maker to pursue approval via PAFI.
Q: What is ASTM?
A: ASTM International states, “The high quality of ASTM International standards is driven by the expertise and judgment of members who represent industry, governments, academia, trade groups, small and medium size enterprises, consumers, and others. Their contributions, and the consensus process, are why ASTM international standards are known for high quality and market relevance across many industries.” ASTM is broad reaching internationally accepted technical standards for a wide range of materials and products utilized by major industries, beyond just fuels and aviation.
When a fuel has received an ASTM specification, the industry can be assured that the specification is well conditioned, addressing the key facets of the fuel performance characteristics, compositional requirements, and that the tests for those pieces have been vetted for precision and accuracy. This is especially important for the novel ingredients of fuels offerings. Lycoming applies ASTM and other voluntary consensus specifications to identify potential fuels for approval. Learn more about ASTM at their website, www.astm.org.
Q: What fuels are approved by Lycoming Engines?
A: Approved fuels are identified in the most current revision of Service Instruction 1070: Specified Fuels for Spark-Ignited Gasoline Aircraft Engine Models.
Q: How does a fuel get added to Service Instruction 1070 as an approved fuel?
A: Safety of the Lycoming engine fleet is of the utmost importance. Before it approves a fuel for use in its engines, Lycoming must first undertake a rigorous evaluation to ensure that the fuel will operate predictably within the engine’s entire operating regime. This evaluation includes a full certification plan & data package that is ultimately provided to the FAA. Once approved, the fuel becomes part of the engine’s TC and is listed in SI 1070.
Q: Who decides which fuels are approved for use in Lycoming Engines?
A: After rigorous evaluation to demonstrate that the fuel will perform predictably and safely in all aspects of the engine’s operating envelope, Lycoming submits its data and certification package to the FAA for review and approval. Please reference SI 1070 for the latest list of FAA approved fuels for use in Lycoming engines.
Q: Has Lycoming tested GAMI’s G100UL fuel?
A: No. GAMI chose not to participate in the collaborative PAFI process and instead chose to pursue approval via a direct STC process. Because GAMI submitted its data direct to the FAA, Lycoming was not involved in the certification or testing of GAMI’s G100UL fuel. In addition, because there is no method for a TC holder to obtain technical information related to an STC, Lycoming does not have the technical information necessary to make any determination as to the airworthiness of G100UL fuels when used in Lycoming engines.
Q: Why hasn’t Lycoming approved GAMI’s G100UL fuel?
A: Because STCs are separately approved by the FAA without TC holder involvement, holders like Lycoming do not typically separately approve them after the fact. In essence, GAMI chose to pursue an aftermarket approval instead of collaboratively working with industry partners through the PAFI process.
Notwithstanding GAMI’s decision to pursue an STC, Lycoming is committed to finding an unleaded solution in any form, and we strongly encourage GAMI to resubmit its fuel for testing through the collaborative PAFI process.
In addition, Lycoming has remained willing to test any candidate fuel, including those submitted to PAFI or approved via STC (like G100UL), so long as we can ensure our testing supports the safety of the flying public. To do this, Lycoming must be provided with appropriate technical documentation so we know what we are testing, and we must be able to provide appropriate guidance to the FAA, the industry, and the flying public regarding the use of any tested fuel in our engines. To date, GAMI has advised that it will not provide Lycoming with access to any technical information related to G100UL fuel unless we agree that we will not disclose our findings. In other words, GAMI has demanded that as a condition to allowing Lycoming to test its fuel, Lycoming must agree to conditions that would limit our ability to disclosure.
To ensure the safety of the flying public and to meet its obligations as a TC holder, Lycoming has refused this “gag-restriction.” If we determine that any candidate fuel creates a safety issue when used in our engines, we must be able to appropriately warn the public and the FAA. We hope that GAMI will drop its gag-restriction and join the collaborative industry process so that G100UL can be evaluated and approved in a manner that ensures the safety of the flying public.
Q: What happens if I run GAMI’s G100UL (or any fuel that is not listed in SI1070 as an approved fuel) in my Lycoming Engine?
A: G100UL has been approved via STC and not via PAFI. As a result, customers should contact GAMI as the STC holder for guidance regarding use of G100UL, including warranty coverage. Because we do not have technical information associated with the STC, Lycoming cannot provide guidance on use of G100UL.
Lycoming evaluates warranty claims on a case-by-case basis in accordance with the terms of its Limited Warranty. However, customers should be aware that Lycoming’s Limited Warranty excludes damage associated with operations outside Lycoming’s published specification, including the use of non-approved fuels. In addition, use of any STC approved fuel constitutes modification of the engine in a manner not approved by Lycoming, and the engine no longer meets its original type design.
Lycoming recommends customers use fuels identified in Service Instruction 1070.
Stop back to this webpage for the most up-to-date information around Lycoming’s unleaded fuel efforts.
