The Long, Twisted And Slightly Ridiculous Story Of Avgas (Part 1)


For decades, the general aviation industry has struggled with finding a replacement for leaded avgas without success. The biggest driver of this failure is that there’s no reason to do so because the industry has been given an exemption to continue using lead. In this two-part series, AVweb’s Paul Bertorelli explains how industry inertia and bureaucratic foot dragging killed efforts to eliminate lead from aviation fuel. See Part 2 here.


  1. Once again, an awesome video production on a subject important to all of us here. You’ve outdone yourself with this one. Thank you for all your research. These videos should be required viewing for every aviator / airplane owner.

    I attended George Braly’s forum at Airventure and sensed HIS frustration with the FAA. I didn’t realize he’d aged THAT much, however 🙂 .

    • Both of these videos should be required viewing for all FAA staff as well as every member of Congress. It’s about time someone should show those knot heads what a mess this whole thing has become. If this doesn’t get their attention, nothing will!

      • Hate ta tell you, John … NOTHING will. They have NO PROFIT MOTIVE. They could give a damn less, either way. I was SO frustrated listening to the acting Administrator spewing superlative government euphemisms in every other sentence at Airventure. If BS could become productive, the FAA would be #1 🙁

  2. Paul

    Your 2 videos are great journalism. It takes real talent to connect the dots on how we got to where we are today in an engaging and relatable way that honours the facts and the science but also explains the policy “challenges” that surrounds this issue.

    My only comment is that I think you should have mentioned the fact that all TEL comes from one factory in England. If that factory were to suffer a catastrophic accident the problem of no 100LL gas is going to get a lot more real for those airplanes that can only run on high octane Avgas.

  3. Well produced videos with not much new, but a good summary for those who have not paid attention the past 20+ years. It does include though a few major presumptions that skew the arguments. (1) Pilots of recreational aircraft like the author’s Cub should stop whining about higher fuel price. In reality, higher fuel prices for light aircraft go straight to the hourly cost of flight instruction and rentals. This can be the show stopper for new pilots. (2) The 2/3rds of aircraft owners whose airplanes do not need higher octane fuels because their engines are TC’d or STC’d for auto fuels should suck it up and underwrite the cost for a drop-in replacement for people who fly more expensive piston aircraft, often for business, and can often write off the costs of fuel unlike the majority of aircraft owners. (3) Ethanol-free fuel is largely unavailable. Quite the opposite is true – ethanol may not be pumped through gasoline pipelines, therefore by definition all fuel terminals have ethanol-free fuel. Ethanol is transported by road or rail and blended into ethanol-free fuel at the terminal before delivery to gas stations. See for a list of 16,830 gas stations currently selling ethanol-free fuel in the United States, compared to only 3,523 FBOs currently selling Avgas, according to Airnav. (4) The STC process has high liability risks. Has the EAA or Peterson Aviation ever been sued for a loss due to the use of their Autogas STCs? That would be news to me. (5) Ethanol blends are a show-stopper. Rotax and some other newer manufacturers of engines for light aircraft include common ethanol blend levels in their TCs. Obviously auto engine conversions such as the Viking engines are fine with ethanol. But any engine approved for ethanol blends is better run on ethanol-free. (6) Self-fuelers do not contribute to aviation tax revenue, so airports are losing out by not offering autofuel alongside Avgas and Jet-A. In fact, in some states, an aircraft owner can file for a refund of highway taxes on autogas purchased at his local gasoline station, resulting in even lower cost of fuel. Lastly, it would be good for the author to investigate the widespread use of autogas at European GA airfields and explain why this is so. And why the same companies there that deliver Jet-A and Avgas also deliver ethanol-free autogas. And airports with much less traffic than a US GA airfield someone manage to offer all three fuels but our GA airports claim they do not have the money for a small above-ground fuel system such as those from U-Fuel. Ultimately free markets should and can sort this out. With the FAA wanting to control everything, and government-owned airports run by people with poor understanding of aviation fuels, I predict the same slow progress towards no solution, but at a continued high cost to taxpayers. In the meantime, mogas will continue to be widely used in sport aviation, but will not be sold officially by other than the most forward-thinking airports.

    • Hi Kent,
      “Obviously auto engine conversions such as the Viking engines are fine with ethanol.” Don’t forget: It’s not just about the power plant. Fuel tanks, fuel lines, sealants, O-rings, filters, fittings and all that other stuff can be show stoppers too.

    • You lost me on number 1.

      On, number 2, not sure of your point either. All I can say is I think you have bad data. I do not believe 2/3’s can legally run Mogas because they do not currently have the STC. Btw, why is the STC so expensive?

      3 is just misdirection. If I can’t get it delivered to my plane or taxi my plane to the pump, why should I give a rat’s behind how “available” Mogas is? BTW, how many law suits have been launched on ethanol free Mogas providers?

      4. again, who cares? Why is this relevant?

      5. Interesting.

      6. As usual, I will invite you to start selling Mogas on airfields. While Paul is looking into the European situation, perhaps you should find evidence of this HUGE anti Mogas conspiracy that you seem to think is a thing.

      I think if you looked closely you’d find business use of high performance piston aircraft suffered greatly since the IRS changes back in the mid 2000’s. My local fields that have survived are now seeing more turbine traffic than high performance piston. Business users are generally the survivors, those building time towards a turbine, or part of the much smaller population of people who have a true need that can still be filled economically by a piston with the IRS limitations.

      Finally, I’d love to have free markets sort this out. Could you find one for us? They seem to have become things only spoken of in academia without real world examples continuing to exist in the wild.

    • (1) Pilots of recreational aircraft like the author’s Cub should stop whining about higher fuel price. In reality, higher fuel prices for light aircraft go straight to the hourly cost of flight instruction and rentals. This can be the show stopper for new pilots.

      Sorry, but this makes no sense. We shouldn’t complain about the higher fuel costs because they’re a show stopper for new pilots? Fractured logic.

  4. Good articles 1 and 2. I didn’t see much on the FBO’s point of view. I talked to my home airport FBO. They can’t afford multiple fuel tanks and pumps so they only sell Jet A and 100LL. The types of fuel that they buy are limited to what they can sell. Right now there is no market for 100UL or 94UL at most FBOs so they don’t buy those fuels. Swift Fuel’s 94UL is nice but can’t be used in high compression engines. It’s unlikely that a FBO would spring for separate fuel trucks for 100UL and 94UL. They would sell more 100UL than 94UL since 100UL would work in low or high compression engines.

    As an owner with a Lycomine O-360-C1F 4-cylinder engine, I would be willing to buy 94UL or 100UL if either was available at my airport. Unfortunately, GAMI left my low compression engine off the AML for 100UL although Swift Fuels has an STC for my engine. My engine doesn’t have a MOGAS STC available and even if it did I’m not going to lug 8 – 15 5-gallon cans of 93UL from the local ethanol-free gas station in my Subaru Outback. One of the troubling things about MOGAS is the less rigorous certification and inspection processes that occasionally result in contaminated fuel. That happened to one of my cars and it was tough to start and ran quite rough until a mechanic diagnosed the problem as fuel contamination. I don’t want that to happen in the air.

    Yet another study like EAGLE isn’t going to speed anything up after 30 years. Isn’t the definition of “insanity” continuing to do the same thing while expecting different results?

    A crisis that applies market pressure is one sure way to jump start this process. Removing the exemption for lead in AVGAS would be the surest way to create such a crisis but there would be a lot of pain caused to aircraft owners in the process. An alternative to a crisis is to make selling 100UL so profitable that manufacturers and distributors would spend money to make more money. What about using the Aviation Trust Fund to help this process? Some of the $3.9B for Airport Infrastructure could incentivize a lot of GA airports to bring in separate 100UL trucks for owners with the GAMI STC. The FAA could help a lot by expanding GAMI’s 100UL STC AML to include other engines, like mine. This would be a bold step for an agency that is so mired in bureacracy and would require strong leadership. However, it would directly support the FAA’s mission to improve aviation safety by removing lead from the air and water.

  5. The only thing I think should be added to the videos is an analysis of the ability of the GA fleet to absorb any cost increases due to a fuel change. Maintenance, Insurance and hanger costs have already gone up considerably in the past few years and over half of the pilots that I know are barely able to keep up with the increased costs as it is. Any significant increase in fuel costs or in required engine/aircraft modifications could cause a large portion of GA pilots to decide it is no longer affordable to fly. With a reduced number of customers the prices would go up even further causing a significant downward spiral in number of GA pilots. I could easily see a future in which most recreational pilots are limited by costs to small 100hp type aircraft and most cross country flying by individual owner operators goes away.

  6. The GAMI STC AML which covers your plane and the entire fleet of gasoline-powered engines has been fully approved by the Wichita ACO, and has been sitting at HQ headquarters for 4 1/2 months waiting on an executive’s signature (or permission for the Wichita office to sign it). In my opinion, it faces two problems: 1) the FAA can’t sign it and still claim that E.A.G.L.E ($120,000,000) of funding for the FAA is still needed if a drop-in replacement has already been found, and 2) The five oil companies currently manufacturing 100LL have powerful lobbies and don’t want their fuel to be replaced by an unleaded one.

    Achieving 100 Octane Unleaded Fuel is no longer a technical problem. It is a political one.

  7. Great article Paul. One more problem with mogas (even ethanol free) that I haven’t seen mentioned is that it will turn to varnish and clog jets if it sits for a month or two in the carb. Avgas will not do that. It’s very common for people to go a couple of months without running the engine.