The latest update from Eliminate Aviation Gasoline Lead Emissions (EAGLE), an initiative between the FAA and aviation industry to transition general aviation to unleaded avgas by 2030, notes that everyone involved has a part to play in the path to an unleaded fuel.
“As the general aviation community works toward this goal, the role of aircraft owners cannot be overstated,” EAGLE officials said in the initiative’s October 2024 update. “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,” they continued. “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.”
EAGLE officials note there are three “promising” unleaded fuel candidates.
The companies working on developing an unleaded fuel are pursuing either a fleet authorization under the FAA’s 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,” EAGLE officials noted.
Those working on the new fuel must “not only prove their products’ safety and compatibility with the existing fleet,” but also demonstrate to the entire GA community “that their product is reliable.”
“Aircraft owners need assurance that switching to a new fuel won’t void manufacturer warranties,” the update noted. “They also need to be confident that it won’t cause damage to paint, electronics, engine components or fuel systems.”
One OEM has already advised its customers not to use the unleaded fuel developed by General Aviation Modifications Inc. (GAMI) — at least not yet.
In June 2024, Cirrus Aircraft released a Service Advisory that warned owners that using the STC-approved G100UL would void their warranties.
“Cirrus is engaged in a comprehensive testing and evaluation program of the GAMI G100UL fuel,” company officials said in the Service Advisory. “Working in coordination with GAMI, our key powerplant partners — Continental and Lycoming — and the FAA during this process, the goal is to ensure operational safety of both the powerplant and airframe fuel systems.”
“While some aspects of the initial Cirrus testing of the GAMI G100UL fuel are encouraging, other areas, including materials compatibility, remain inconclusive,” the advisory continued. “At this time, Cirrus does not approve the use of GAMI G100UL fuel in Cirrus SR Series airplanes. Additionally, Cirrus currently does not warrant or represent in any way an operator’s use of the GAMI G100UL fuel in SR Series airplanes. Per Continental and Lycoming, only approved fuels may be used for an engine to be covered by warranty. As the GAMI G100UL fuel is a non-approved fuel per Continental and Lycoming, engines known to have run this fuel may not be covered by the current OEM engine warranty.”
According to EAGLE officials, the aviation supply chain also will need assurances about the new unleaded fuels.
“This next fuel must be produced, distributed, stored, possibly co-mingled with other fuels, pumped, and consumed without causing damage or requiring significant equipment modifications,” the update said.
The Three Contenders
GAMI’s G100UL, which secured a broad Approved Model List (AML) STC for its fuel in 2022 for piston airplanes, is already being sold at Reid-Hillview Airport (KRHV) in California, which banned the sale of 100LL in January 2024.
Swift Fuels has also secured its first STC for the use of its 100R unleaded fuel 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,” EAGLE officials said.
Meanwhile, LyondellBasell/VP Racing’s UL100E is progressing through the PAFI process, having completed about 25% 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.
GAMI officials say they will not go through the ASTM process.
While the search for an unleaded fuel for general aviation has been going on for years — it took GAMI 12 years to get STC approval for its fuel — EAGLE officials claim that Congress and the FAA’s commitment to the initiative is underscored by the 2024 FAA Reauthorization, which supports the continued availability of 100LL until the end of 2030 or when a certified unleaded alternative is available at airports.
They added that Alaska, a state heavily reliant on piston-engine aircraft, has been given an extended timeline protecting continued availability of 100LL through the end of 2032.
Meanwhile, it’s imperative that general aviation pilots and aircraft owners “stay informed and engaged as this transition unfolds,” EAGLE officials said.
“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 continued. “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,” they concluded. “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.”
For more information: FlyEAGLE.org
I Rember that the same thing happened to cars when they changer from led to nonlead.
To fix the problem in cars they harden the valves & rings. When this was first brought up
I suggested the same thing for aircraft. When I said this on another form The comment I received was more harder than the that solation than could be done with aircraft.
You do realize that aircraft engines are very expensive. Rebuilding them would cost a fortune.