FAA Readies For PAFI Unleaded Fuel Tests


The FAA says engine cell testing of one of three contenders actively being considered as a replacement for 100LL avgas will begin later this year at the agency’s William J. Hughes Technical Center in Atlantic City. In a statement to AVweb, the agency said the fuel developed by a partnership between LyondellBasell Industries and VP Racing will also undergo flight testing as part of the approval process through the Piston Aviation Fuels Initiative. If it meets all the various standards required for a new fuel, it will earn “fleet authority” and be approved for use in all piston aircraft.

The FAA is now lining up test beds for the LyondellBasell/VP Racing fuel. “The FAA is working with various aircraft equipment manufacturers and operators to support flight testing of a mixed fleet that includes eight different aircraft models of six different makes,” the agency said. “We will also work with engine manufacturers to support testing for 10 different makes/models. We will be able to provide additional details on the specific manufacturers that will be involved in the testing after arrangements have been finalized during the next few months.”

LyondellBasell/VPRacing is the last contender using the PAFI process to get its fuel approved. Phillips 66 and Afton Chemical paused their testing earlier this year after technical issues during a 150-hour endurance test of its fuel and was also using the PAFI route. Swift Fuels is continuing development of its replacement fuel but will get it approved via Supplementary Type Certificate. General Aviation Modifications Inc. has already obtained STC approval for G100UL that covers every spark ignition engine used in certified aircraft in the U.S. and is now conducting an extended real-world evaluation using AOPA’s Beech C55 Baron with one engine running mostly on G100UL and the other on 100LL. They have about 150 hours on the test regimen.

Russ Niles
Russ Niles is Editor-in-Chief of AVweb. He has been a pilot for 30 years and joined AVweb 22 years ago. He and his wife Marni live in southern British Columbia where they also operate a small winery.


  1. What happens if this new fuel also fails due to “technical issues”? And will it be subject to the same level of scrutiny G100UL has been through?
    It’s just too closed of a process for me to really trust it (PAFI/EAGLE).

  2. GAMI’s G100UL will probably be widely available before the new PAFI/EAGLE fuel completes testing, let alone widespread availability. FBOs under pressure to switch to unleaded fuel (California mostly) might switch to G100UL since it will be the only available unleaded 100 octane fuel for a while. Pilots who do not have the GAMI G100UL STC will avoid airports that only sell G100UL. FBOs will only buy G100UL if it can be used in existing fuel farms and there is enough demand to sell it. Some California airports are already subsidizing the purchase of the GAMI STC (about $600 for most single-engine aircraft).

    Suppose the new fuel passes the tests. As far as I can determine, there are no requirements for the PAFI/EAGLE fuel to be fungible with G100UL and GAMI says it’s unlikely. At that point (2030?) there would be another approved non-STC 100UL fuel that wouldn’t have much if any demand.

    Meanwhile Swift Fuels is trying to get a STC for 100R but they are way behind GAMI.

    Economics and bans on leaded fuels will drive who survives but it will take years to switch to unleaded AVGAS if market pressure is the only factor.

    One way to accelerate the process might be for the FAA to either declare G100UL usable in all piston engines without an STC but that would undermine GAMI’s revenue and the FAA would have to treat all STC fuels the same way. Another, better, approach would be for the FAA to subsidize the purchase of any qualified 100UL fuel STC like they did with ADS-B adoption.

    It’s unlikely that the FAA would interfere with market factors by favoring a particular company like GAMI. That’s not their mandate but subsidizing the purchase of an STC for any qualifying 100UL fuel, such as Swift Fuels 100R, would be a positive step in accelerating the transition.

  3. So the FAA is going to “test” fuels–some of which (GAMI) they have already approved for “EVERY SPARK IGNITION ENGINE USED IN CERTIFIED AIRCRAFT IN THE U.S.”

    GAMI spent millions of their own dollars earning the FAA STC–(above)–which the FAA certified–and now they want to “help” develop a “new fuel.”

    It reminds me of the old line about “Jumping in ahead of the parade, and pretending to lead it”!

    And they wonder why they have such a poor reputation from the people that they are trying to “regulate.”

  4. The FAA fought GAMI all the way through their STC process, which as finally “approval for G100UL that covers every spark ignition engine used in certified aircraft in the U.S.” They are now just wasting our money and possibly killing any potential for GAMI to recoup the money they spent to get G100UL approved.

    • You can say the FAA fought GAMI, but tell me of another STC this far reaching, with possibly quite serious consequences. That one stood alone.

      • The Mogas STC seems pretty similar. Perhaps even worse consequences there, since it’s for using a fuel that wasn’t specifically engineered for aviation use.

  5. If it exists now, why isn’t it being tested now? At the very least, performance testing can be done now, and those that pass can go on to endurance testing.


    Timeline for Widespread Adoption:

    • In the best-case scenario (3-5 years), everything goes smoothly, and the new fuel is quickly approved with minimal changes needed to airplanes.

    • More likely (5-10 years), it might take longer for testing and making sure there’s enough fuel available for everyone. Some airplanes might need minor adjustments to use the new fuel.

    • In the worst-case scenario (10+ years), there could be unexpected problems, or airplanes might need bigger changes to use the new fuel, causing a longer delay.

  7. More taxpayer waste with $35T in debt and collapse of the dollar on the horizon. We could have had far less expensive, ethanol-free, lead-free mogas on our airports, 40 years ago when the FAA first approved it. The world’s leading aircraft engine maker (Rotax) designs all its engines to run on Mogas. UL Power and other new aircraft engine makers do the same. In the future, the fuels that should always be available are Mogas and Jet-A or diesel, as the latter powers the most efficient, least polluting powerplant of all, compression-ignition (diesel) engines.

  8. The more candidate fuels, the better we can find one that works and is economical.

    It is odd people railed against being given choices given no one knows what G100UL will cost at the pump yet. It has been almost 2 years since the STC was granted and there are ZERO retail pumps dispensing G100UL. Inventing and certifying a fuel is not the same as producing and delivering it, obviously.

    Lyondell and VP Racing do actually produce and deliver fuel, so that part of the equation won’t be such a struggle.

    May the best fuel win.

    Mike C.

  9. Hi Russ,
    “General Aviation Modifications Inc. has already obtained STC approval for G100UL that covers every spark ignition engine used in certified aircraft in the U.S.”

    Be careful, this isn’t true. “aircraft” should read as “airplane”. GAMI has said helicopters and others may be supported some time down the road.

  10. GOVERNMENT created this issue. It failed to come up with an unleaded fuel specification–so GAMI (arguably the best piston-engine fuel experts (largely due to their invention and certification of their FAA-approved GAMI-JECTOR fuel injection research) spent their own money to develop the STC–which doesn’t require a new engine.

    Government (The FAA) STCd the GAMI fuel for “approval for G100UL that covers every spark ignition engine used in certified aircraft in the U.S.”

    Now the FAA wants to further cloud the issue with OTHER certification. One has to ask–“WAS THE FAA WRONG THEN (in issuing the STC?) or “IS THE FAA WRONG NOW?” (by opening the PAFI program?)

    The industry is bypassing the inept FAA bureaucracy in adopting foreign-made engines that can use EXISTING fuels (Mercedes Jet-A engines, and Rotax engines that can run just fine on MANY fuels–including auto fuel). The U.S.–former world leader in General Aviation technology–has fallen to “Third world” status due to lack of reasonable standards and predictable certification standards.

    The FAA actions have all of the makings of the Marx Brothers for their farce comedy regarding certification–or the Three Stooges for ineptitude–or perhaps they take their inspiration from Rube Goldberg for making a simple solution very complex. As the old saying goes–“The basis for all comedy is the misfortunes of others” or–given the time and expense of their dithering–Steve Allen’s “Tragedy plus time equals comedy.”

    “Comedy” aside–You can’t INVENT a process this flawed!