EAGLE and its members are working to facilitate a national transition to unleaded fuels that is safe and smart. It is working to ensure availability of fuels that meet the safety needs of the general aviation fleet. For more information, please refer to the comprehensive article by the National Air Transport Association (NATA) Unleaded Avgas Conversion Considerations for Aviation Fuel Providers and EAGLE’s Guidance on Transitioning a Flight School to Unleaded Avgas.

One challenge is a limited fuel storage and dispensing infrastructure at airports. FAA encourages airports and/or FBOs to take enabling actions, such as installing an additional tank or leveraging a spare tank to store/dispense unleaded fuel while maintaining 100LL through the transition period. Given the relatively low avgas demand, the costs to add an additional tank may be prohibitive.

Another challenge is the lack of understanding of the pathways to authorize fuels. Industry stakeholders need an understanding that any new fuels must meet the needs of aircraft owners and are compatible with production, distribution and dispensing systems. To learn more about these pathways, visit flyEAGLE.org.

A small percentage of the current aircraft fleet may require modifications either to their operating limitations or the hardware to allow safe use of unleaded fuels. This is being addressed via the Research, Development, and Innovation and the Unleaded Fuel Evaluation and Authorization pillars of EAGLE. To learn more, please reference UAT ARC Final Report – Part I Body, various parts of Section III and FAA UAT ARC Final Report Part II Appendicies.

EAGLE (Eliminate Aviation Gasoline Lead Emissions) 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.  

The EAGLE initiative is modeled after CAAFI (Commercial Aviation Alternative Fuels Initiative) and overseen by an executive committee that comprises senior leaders in aviation and the FAA. Work on the EAGLE initiative is organized into four pillars, each led by an industry expert or government leader. 

The EAGLE framework encompasses four pillars designed to foster the necessary evaluation, authorization, regulatory, innovation, and infrastructure solution sets to enable the commercial viability of unleaded aviation gasoline needed to facilitate the transition. The initiative supports the White Houses’s sustainable transportation and broader environmental priorities and is part of the ongoing effort to build a sustainable aviation system.  

Many aircraft in the current general aviation fleet need 100-octane fuel in order to avoid engine detonation and catastrophic engine failure. Lead has long been used as an additive to boost fuel octane, allowing these aircraft to fly safely. Finding a suitable unleaded substitute has long been a goal of the general aviation industry and the FAA. While the mission has been challenging, there has been recent progress. As important, the unleaded transition must be safe and smart, and airports and communities must provide a supply of 100 low-lead (100LL) for all aircraft to fly safely during this transition.

While levels of airborne lead in the United States have declined 99% since 1980, there is still more work to be done to lower risks of lead exposure to communities adjacent to general aviation airports. Accordingly, the general aviation industry and the FAA are working hard to eliminate all lead in aviation fuel as soon and safely as possible, through the Eliminate Aviation Gasoline Lead Emissions (EAGLE) initiative.

General aviation encompasses approximately 289,000 aircraft in the United States, of which approximately 222,000 are piston-powered and utilize aviation gasoline. The general aviation community contributes $246.8 billion annually in total national economic contribution and 1.2 million jobs in communities across the country. Over 5,000 public-use airports and more than 15,000 private landing facilities provide an important, and sometimes the only, fast, reliable, flexible air transportation for small and rural communities.

• EAGLE, or the Eliminate Aviation Gasoline Lead Emissions initiative, has set the goal of 2030 or sooner for the elimination of lead emissions from general aviation. The full transition to an unleaded aviation gasoline will require good planning, processes, execution, accountability, and active stakeholder participation (including industry and government).
• While the goal to eliminate all general aviation aircraft lead emissions is 2030 or sooner, airports, Fixed Base Operators (FBO), and airport users are encouraged to implement constructive mitigation measures today to reduce lead emissions and plan to facilitate a safe transition.
• In the near term, airport communities can offer unleaded fuel types while maintaining 100 low-lead (100LL) to ensure safe operations of those aircraft that must still use it during the transition. A key enabling step for airports may include installing additional fuel infrastructure, e.g., an additional tank, fuel truck, or leveraging an available tank. Airports are also encouraged to include transitioning to unleaded fuels as part of their airport planning initiatives (e.g., master plans).

Individual fuel suppliers, distributors, and airports consider multiple factors when determining if a fuel is commercially viable, such as:

•  Product’s authorization or approval for use in specified engines, fixed wing aircraft, and rotorcraft (pursuant to Supplemental Type Certificates [STC] or another FAA program)
• Percentage of the active, piston-engine, certificated and non-certificated, fixed- and rotor-wing fleet operating out of the specific airport that can use the fuel
• Availability of an ASTM or independent specification detailing specific requirements for the quality and safe use, production, and distribution of the fuel
• Sufficient quantity of active fuel production to ensure consistent availability through an established distribution network
• Sufficient risk mitigation protection with established product liability insurance coverage as currently provided to airports and Fixed Base Operators (FBOs) selling 100 low-lead (100LL)
• Unleaded fuel’s ability to be purchased by any interested party without restriction throughout the country

It is important to note that under both the fleet authorization pathway and the supplemental type certificate (STC) pathway, aircraft owners and operators will need to take specific actions in order to safely operate using the fuel:

• Implement a fleet authorization by revising the operating limitations in the flight manual on their particular aircraft and replacing the fuel placard. Detailed instructions for doing so will be included as a part of each authorization.
• Implement changes to the aircraft, typically via service bulletins or installation of an STC.
  • For aircraft with a standard airworthiness certificate, the alteration is performed by a certificated mechanic or authorized entity and must comply with the type certificate (TC)/STC.
  • Owners of Special Light Sport Aircraft (SLSA) can implement the authorization after the SLSA aircraft manufacturer issues an authorization to do so.
  • Owners of experimental aircraft must individually determine appropriate unleaded fuels. Those owners may develop their own compatibility or solicit input from the TC/STC holder for data pertinent to their aircraft. Many experimental aircraft have engines and fuel systems in common with aircraft with standard airworthiness certificates.

In the short-term, airports, Fixed-Base Operators (FBO), and airport users can take steps to reduce or minimize potential exposure to aircraft lead emissions:

• Work to offer additional unleaded fuel types to facilitate the transition.
  • A key enabling step may include installing additional fuel infrastructure, e.g., an additional tank or a fuel truck. Alternatively, airports may be able to utilize a spare tank.
• Minimize engine idling time and run-up times of piston-engine aircraft
• Promote airport and pilot awareness
• Increase distance between pre-flight/maintenance run-up locations and people on/off airports by relocating run-up locations or distributing run-ups to multiple locations.

These measures are summarized at a dedicated FAA webpage.

Aviation gasoline production equates to approximately 0.14% of motor gasoline consumption and is currently only produced in 7 of the nation’s 125 refineries. The limited amount of production, coupled with the highly safety-critical nature of the fuel’s intended market constrains the distribution of this fuel to a system of barge, rail, and truck, which represents the most economical means of transportation.

The transition to unleaded fuel, poses unique challenges. The safety-critical nature of aircraft operations necessitates specialized handling of aviation fuels to ensure their cleanliness, dryness, and adherence to specifications throughout the distribution system. While the production and distribution of new unleaded aviation gasoline could differ from the current system, the reliance on the product arriving clean, dry, and on specification will remain. This, coupled with the continuing small volume of product compared to other transportation fuels, will likely result in the continued reliance on specialized handling and the use of barge, truck, and rail for shipment.

• ASTM aviation fuels are color-coded to mitigate the chances of misfuelling.
• EAGLE partners have been working together to enhance existing misfuelling guidance and training. EAGLE is promoting the use of misfuelling guidance and training for use by airports, Fixed-Base Operators (FBOs), flight schools, and others. Please reference helpful resources on the Energy Institute’s Practice 1597 web page, NATA’s misfuelling prevention web page as well as the EAGLE’s Guidance on Transitioning a Flight School to Unleaded Avgas paper for more information.