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The General Aviation community has been fraught with the tumultuous changes relating to the switch from leaded to unleaded aviation fuel, from fights with the community to the lack of available alternatives. Many FBOs and pilots are feeling pressure from the public to switch over to unleaded avgas and despite there being FAA-certified unleaded fuel alternatives, there may not be commercial availability to make the change. Unleaded fuel maker General Aviation Modification recently announced it had a 1.2-million-gallon tank of G100UL Avgas and that it was now commercially available, but one aviation group disagrees.
The National Air Transportation Association issued a statement, asserting that the unleaded fuel alternative, G100UL, is not commercially available for distribution and sale in the U.S., "due to the fact it does not have an ASTM International product specification." The FAA can approve the use of avgas by aircraft type or engine but does not regulate or oversee the production, handling, operation or quality control. Without this oversight from the FAA pilots, airports, FBOs and avgas distributors have relied on the ASTM International (previously known as the American Society for Testing and Materials). The ASTM product specifications ensure the safe and economical operation of an aircraft and that the fuels are clean, dry and free of contamination before use.RELATED STORIES:First unleaded fuel candidate passes PAFI testing, advances to next stageFrom 100LL to G100UL: What comes next for avgas and why today is historic
In November 2023, the FAA approved the advancement to full-scale engine and flight testing for the unleaded UL100E avgas for piston-engine aircraft, being developed by LyondellBasell Industries/VP Racing. The fuel passes the rigorous Piston Aviation Fuels Initiative testing, becoming the first unleaded fuel to pass the PAFI 150-hour durability test phase. NATA said in its statement that UL100E will complete PAFI full-scale engine/flight testing and the ASTM process within 12 to 18 months. Once the candidate completes PAFI testing and has a published ASTM specification, the FAA will approve Fleet Authorization.
The FAA has two approved STCs permitting the use of two unleaded fuels, Swift Fuel's UL94 and GAMI's G100UL, for use by a large portion of the GA fleet. NATA reported that UL94 has been sold nationwide for nine years with an ASTM International Specification. Swift Fuels has also submitted an STC application for 100R, a 100-octane unleaded aviation fuel, and is expecting FAA approval this year. Swift is also seeking an ASTM fuel specification for 100R. NATA points out that G100Ul has FAA STC approval based on a proprietary fuel specification known by the FAA and GAMI, but no industry consensus standard or ASTM International product specification.
"Because the FAA does not indemnify any entity in the supply chain for damages caused by fuel-related issues, fuel distributors and FBOs will similarly lack assurances that the unleaded fuel they are selling will not expose them to liability," NATA said.RELATED STORY:FAA to soon begin testing unleaded fuel on more piston aircraft
Without these supply chain assurances, NATA said G100Ul is not commercially available for distribution and sale in the U.S. GAMI refers to G100UL unleaded avgas as a "drop-in replacement for 100LL avgas that maintains or improves engine performance and, simultaneously, significantly reduces routine maintenance costs imposed by the use of leaded avgas."
Currently, there are no modifications required to use G100UL, other than a placard attached to the engine and refueling ports. GAMI estimates that the unleaded alternative could cost 70¢ to $1.05 more per gallon than 100LL until it is widely available. G100UL is expected to appear first at airports in California, Oregon and Washington in the second quarter of 2024. On its FAQ page, when answering the question as to whether G100UL avgas has an ASTM specification, GAMI said it elected to use the existing and approved STC pathway to obtain approval for GA aircraft and engines. With 13 years of work and research, GAMI said it elected to pursue the STC certification path over joining the PAFI project primarily due to the fact the process began three years after GAMI began its work, and since there was no mechanism within PAFI for GAMI to obtain "credit" for the already FAA-approved work.
GAMI said it is collaborating with large aviation fuel producers to oversee the logistics of production and the four major distributors of GA fuels, Avfuel World Fuel, TITAN and EPIC have all been invited to make arrangements for the transportation of fuel to FBOs in California. As of Oshkosh 2023, none of these distributors had begun making such arrangements. GAMI said it has a plan to begin moving the unleaded avgas to California, Oregon and Washington in the second quarter of 2024 with the later expansion to distribute across the rest of the country. The company has also said that the distributor's supply chain and related infrastructure are the only limiting factor in the widespread and rapid deployment, anticipating the national deployment to take place over a few years.RELATED STORIES:Airports, communities continue to battle over leaded avgas use as G100UL sale nearsEPA determines leaded fuel endangers public health, aviation coalition respondsStates propose legislation to tax, phase out leaded avgasCalifornia county continues fight against sale of leaded avgas, opposes mandate in FAA Reauthorization bill
NATA points out that many fuel distributors and FBOs have agreed to sell unleaded alternatives when they become commercially available, but some communities or legislators are including deadlines that come before the anticipated commercial availability of fuels like G100UL. FBOs in California have felt the weight of the pressure to quickly transition to unleaded fuel, lest they risk facing fines or shutdowns. On Dec. 10, 2024 the Center for Environmental Health shared that it had won a legal agreement with 30 companies selling and/or distributing leaded avgas at 23 California airports. After October 2023, when the EPA published its final ruling that lead emissions from aircraft were causing or contributing to air pollution and endangering public health, CEH's lawyer sent a letter to major FBOs to comply with the court rulings by March 1, 2024.
Many FBOs are facing confusion and fear over the transition. Making the change from leaded to unleaded is a goal that the industry and public share, but changing before testing is complete and commercial availability is achievable could be disastrous. Infrastructure and safety precautions need to be in place before the transition. NATA said when multiple grades of avgas are available at airports, there is a high risk for misfuelling. Mixing different grades of fuel can have unintended consequences or reactions and endanger lives. NATA notes that the FAA does not address the compatibility of mixing different unleaded fuels in aircraft, airport storage tanks or refuelers, and does not recommend mixing any new unleaded fuels with existing unleaded fuels until the FAA and ASTM International have completed testing and concluded whether or not the fuels can safely be mixed.Check out NATA statement here
Along with a risk for misfuelling, some FBOs do not have the tanking capacity to offer more than one grade of avgas. The permitting and approval process to add a second tank can take months or years and is costly. Forcing an FBO to immediately convert to one option, like UL94, would prevent it from offering another, like G100UL. Many federally funded airports are required by the FAA to offer 100LL. Despite this, some airports or local governments have tried to ban the sale, which can conflict with grant assurance from the FAA.
At the recent 50th anniversary Sun ‘n Fun fly-in, the Howard DGA-6 Replica "Mister Mulligan" became the first plane in history to use the unleaded G100UL in an airshow performance on April 10. The pilot, Doug Rozendaal, said there were no operational differences between flying with G100UL and 100LL.
"Based on my experience I believe G100UL is a suitable drop-in replacement for 100LL fuel," he said.
On the same milestone day, GAMI and Vitol Aviation announced that Vitol produced a 1.2-million-gallon tan of G100UL Avgas and that it was now commercially available. NATA issued its statement claiming that the fuel was currently not commercially viable.
"These safety concerns alone challenge the commercial viability of requiring the sale of such fuels at airports," NATA said.
Increased prices, supply chain capacity and the lack of rotorcraft approval are additional concerns NATA noted in its statement. NATA said it is committed to its role in eliminating the use of leaded avgas by 2030 or sooner. The safe transition will require that 100LL remain available.
"NATA looks forward to supporting the use of unleaded avgas that is FAA certified for engines and airframes and meets an ASTM International or other industry-approved specification when it is commercially viable and safe to offer this fuel for sale," NATA said. "NATA will continue to work with all stakeholders toward this goal."