Introduction
The era of leaded 100LL avgas is coming to an end. Environmental concerns and the decreasing availability of the additive tetra-ethyl lead (TEL) make the transition to lead-free alternatives inevitable. A global manufacturer of the lead-based additive, unwilling to invest in new facilities in the face of declining demand, highlights the risk to the entire aviation industry in the event of a production stoppage. Both the USA and Europe are currently actively involved in finding solutions for a smooth transition to unleaded avgas.
Development in the USA
At the IAOPA World Assembly in Washington in May 2024, FAA Director Bruce DeCleene provided information about the US authorities' plans for the transition to 100-octane unleaded avgas. The aim is to introduce an unleaded fuel by 2030 at the latest, ideally earlier. The main requirements for the new fuel are that it can supply all engines currently running on 100LL and is miscible with 100LL to ensure a smooth transition.
The FAA funding programmes PAFI (Piston Engine Aviation Fuels Initiative) and Eagle (Eliminate Aviation Gasoline Lead Emissions) are central to the development of this new fuel. Three competitors from the mineral oil industry are currently vying for pole position in the dominant US market. A clear market leader could emerge in the near future, with the successful launch in the USA serving as a springboard for the European market and other regions.
The GAMI fuel and the market
One hotly debated topic is the marketability of GAMI's fuel. According to George Braly, a co-founder of GAMI, their Avgas 100UL is ready for market launch. They have a supplemental type certificate for all aircraft types and are ready to start deliveries immediately. However, rival companies, which still need a few months to get their fuels approved, are expressing concerns about unresolved issues, particularly in relation to aerodrome tanks and fuel trucks.
The European perspective
In Europe, the decision by the European Chemicals Agency (ECHA) on the extension of the processing authorisation for TEL by the companies Shell, Trafigura/Puma and Warter is imminent. This decision is expected in June. If the authorisation is extended, these companies can continue to produce Avgas 100LL until a lead-free alternative is available. Otherwise, the production of Avgas 100LL in Europe could be discontinued from May 2025, although imports from the USA would still be possible, albeit with increased costs and environmental impact.
IAOPA, together with the GAMA and Europe Air Sports associations, has clarified its position in public hearings and is in favour of international coordination between the authorities. A resolution in support of the introduction of unleaded avgas was unanimously adopted at the IAOPA World Assembly.
Current developments and controversies
A current update concerns the use of GAMI fuel in Cirrus aircraft. Cirrus has stated in a Service Advisory SA24-14 that the warranty for its SR series aircraft will be invalidated if refuelled with GAMI fuel. This is due to open questions regarding the compatibility of the fuel with other materials such as tanks, seals and fuel lines.
GAMI disputes this claim and emphasises that its unleaded Avgas 100UL has been tested for 14 years in its proprietary Cirrus SR22 without causing any problems. The conflict has great potential to escalate and various parties are currently working on a solution and clarification of the situation.
Conclusion
The introduction of unleaded avgas is a decisive step for general aviation. The industry faces major challenges, but also opportunities to improve environmental compatibility and operational safety. The transition requires international co-operation, technological innovation and clear communication between manufacturers, authorities and users. Unleaded avgas will shape the future of aviation and the coming years will be crucial in determining how successfully this transition is managed.
Source references:
AOPA
