GAMI Update on Unleaded Avgas


GAMI’s George Braly and Tim Roehl updated AirVenture pilots on their rollercoaster ride with the FAA on obtaining an expanded STC for their G100UL unleaded avgas replacement. At Sun ’n Fun earlier this year, Braly shared his frustrations with the FAA’s process on approving the expanded STC, noting that the agency had already approved a smaller STC in 2021. GAMI had done the work to prove that G100UL could be used in virtually any spark-ignition aviation engine and had applied for a much, much broader STC.

Critics have said that GAMI should be seeking wholesale approval from the FAA, but even its prime competitor, Swift, has elected to take its 100R fuel to the market through the STC process. In any case, myriad delays in having FAA management actually sign the STC document that has been prepared and approved by the Wichita Aircraft Certification Office have culminated in yet another TAB (technical advisory board), which has, apparently, come back with six “questions” about the fuel, according to Braly. Among them is a request to review the detonation testing, which itself has been highly documented since at least 2010. Another concern was the color of G100UL, which as a light tan could be mistaken for “really poor” Jet-A. The solution is as simple as dying the fuel. Braly delighted in noting that adding the same dye as used for 100LL makes G100UL turn green. The other issues noted by the TAB had actually been noted and answered in the earlier certification documents, according to Braly.

You could excuse the GAMI team for seeming out of patience with the FAA, but there is some good news. Braly reported that management responsible for moving the project forward—in this case, literally signing the already approved STC paperwork—will be visiting the firm’s Ada, Oklahoma, facility in the next two weeks to review some of the concerns and take another look at the voluminous amount of detonation data the company has collected.

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Marc Cook
Marc Cook is a veteran special-interest journalist who started as a staffer at AOPA Pilot in the late 1980s. Marc has built two airplanes, an Aero Designs Pulsar XP and a Glasair Aviation Sportsman, and now owns a 180-hp, steam-gauge-adjacent GlaStar based in western Oregon. Marc has 5000 hours spread over 200-plus types and four decades of flying.


  1. The FAA will go screaming and kicking into approval of either Swift or GAMI’s fuels. Someone will have to make a decision for approval. A successful FAA employee’s career is based upon never making a decision they can be held responsible for..

  2. I’ve already written AZ senators Kelly and Sinema asking them to light a fire under the FCC to get this approval done. (I didn’t bother to write Paul Gosar, because I know there would be no results.) I suggest others write their congressional representatives as well. Maybe the idea that FAA management might have to testify on Capitol Hill about the procedural delays that they’ve introduced could expedite the process.


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