3 min read

Is this the beginning of the end for avgas?

The future of avgas has been a hot topic for decades, with predictions of “the end of 100LL” coming every few years. But lately there has been a renewed urgency about the subject, especially as environmental groups and the EPA have turned up the heat.

To address the uncertainty surrounding avgas, the FAA convened the 100LL Unleaded Avgas Transition-Aviation Rulemaking Committee (UAT-ARC in FAA jargon) in January 2011, a team made up of AOPA, engine manufacturers, the EPA, the FAA and others. The goal of the UAT-ARC was “to recommend an FAA administered process by which any candidate replacement for 100LL avgas could be tested and evaluated for possible certification…It is very important to understand the UAT‐ARC was not chartered to evaluate candidates, or to pick a winner.”

The group recently released its full report. Read the summary here from the Clean 100 Octane Coalition, the full report here and the appendices here. It is difficult reading, but some of the highlights of the report include:

  • “An unleaded replacement fuel that meets the needs of the entire fleet does not currently exist.” So a new fuel is needed and a new way to test and approve this fuel must be developed.
  • This transition will not happen overnight. The group estimates it will take 11 years and cost as much as $73 million to find a long-term replacement for 100LL.
  • The group makes clear that they do not see an immediate threat to the availability of 100LL. While a long-term transition plan is needed, a steady supply of avgas is expected for at least the next 5 years.
  • Many aircraft could run today on lower octane unleaded fuel with little or no modifications. However, higher compression engines (found in Cirrus, Bonanzas, twins, etc.) could not. These higher performance airplanes fly the majority of hours, so this is the major issue.
  • The report makes various recommendations for a deliberate plan to be enacted and shared with the public (the Fuel Development Roadmap–Avgas Readiness Levels).
  • The lead parties would be ASTM (who would create the specs for a new high octane, unleaded fuel) and FAA (who would conduct much of the testing at their Hughes Testing Facility).
  • There is a preference for a new fuel that uses ASTM standards to qualify, and not to use the STC process (as some companies are pursuing).
  • The ARC recommends the creation of a Piston Aviation Fuels Initiative (PAFI), a new industry-government group to shepherd the process along.

The report got a positive reception from most aviation organizations, who praised it as an important first step in a long and complicated process. While it certainly does not identify a solution, at least it begins to define some of the steps that must take place. But not all pilots are happy with this report–the Malibu-Mirage Owners and Pilots Association says we should be skeptical.

What’s your opinion on the future of 100LL? Are you worried it might disappear? Would it effect your decision to buy a new airplane? Is enough being done to address this issue or is the panic overblown?

John Zimmerman
9 replies
  1. Stephen Phoenix
    Stephen Phoenix says:

    I think 100LL will go away; and good ridance. Unleaded aviation fuel will be an improvement; not for the ecology but for the engines. However, the $73M projected cost has all the smell of a boondoggle in the making. It would seem that if there is a profit to be made selling airplane gas, then someone will do it without the FAA and all the alphabet groups getting in the way. If there is not profit to be made, then the $73M will be wasted because the fuel won’t be marketed anyway. If a profit can’t be made, then something different will have to happen(convert to diesel or make gliders or living room furniture out of Bonanzas or something).

  2. Old Bob Siegfried
    Old Bob Siegfried says:

    Good Evening All,

    I am very disappointed with the action taken by all of our alphabet aviation groups. Our guys sound just as bad as the government folks. That does not make either group bad folks. It just means they have fallen prey to the inherent bureaucracy of the system. The better idea is to let industry try what they have developed.

    Auto gas was approved for aircraft use via the STC process. Why not use that same process to approve the fuels that hyave been produced by Swift Fuel, GAMI, and who knows whoever. Regulation and a set of standards will just stifle innovation.

    The current ASTM standars were set AFTER the 100LL was developed. In the days before that standard was set, the engine engineers told the oil industry what they needed and free enterprise worked to find a product that was suitable to the task at hand. What we need is LESS regulation and more use of a free market.

    Waste of time and a waste of 73 million dollars as far as I can see.

    Happy Skies,

    Old Bob

  3. Rick A
    Rick A says:

    IMHO, the $73 Million and involvement of all the alphabet orgs is the price one has to pay to “attempt” to limit the inevitable class action law suits when someone’s engine fails using the new fuel. I can see all those shysters preparing the filings already. ;)

    It is the inevitable CYA by everybody except the FAA who can claim sovereign immunity, I think.


  4. Kayak Jack
    Kayak Jack says:

    My plane (’63 model 172D) is placarded to use 86 octane fuel ONLY. Obviously, that isn’t happening. But, if seals and lines were changed to materiel that can work in alcohol as cars do, it would be possible.

    BUT, I’ve heard there are vaporization problems that can occur with the alcohol at altitude, causing vapor lock. I’d rather not have to stop and add ice to the outside of the fuel lines or carb at altitude.

    A question that I’ve never seen addressed is, are there any documented cases of problems caused by a minute amount of lead in the fuel? (That is, other than any wild claims by groups purporting to represent the environment, but only representing themselves.)

    • DougH
      DougH says:

      Even 10% alcohol in gasoline will cause more problems than (simply?) changing seals and lines can fix. Have you seen what 10% alcohol can do to an entire carburetor or a fuel tank or fuel pump or any component that comes in contact if those components are not specifically designed and tested to be compatible (usually complete materials upgrades are required)? Now the ethanol lobbying groups are in the process of upping auto fuel to 15% ethanol. They have 20% ethanol in their sights as a goal. All to be used in engines with fuel systems that were *never* designed and tested for compatibility. Even more importantly, what about the fuel mixture changes when adding these varying amounts of alcohol? The engines will run leaner and mixture compensation will likely be required. What about the loss of range due to lower energy content? It’s a slippery and dangerous slope…

  5. MiketheCFI
    MiketheCFI says:

    Unfortunately when it comes to auto gas, the EPA has allowed a number of states to demand & regulate their own gasoline blends. IIRC, there are upwards of a dozen different state required formulas for gasoline- and most of them change according to the season, and there’s no guarantee that they won’t radically change from year to year, making it impossible for the FAA to certify any particular kind of modern auto gas for use in airplanes.

  6. Kayak Jack
    Kayak Jack says:

    Mike, what you say is true. And yet, there are aircraft flying form my field using automotive fuel. Someone’s overcoming the problems.

  7. Joe Schlunk
    Joe Schlunk says:


    Kayak Jack is correct in insinuating that there is no scientific basis for the elimination of lead in the miniscule amount of 100LL that is burned globally. I have read that more auto fuel is burned in one-half of a day that 100LL in a year.

    However, it is not the environmental nazis that will bring the demise of 100LL; the lack of demand will do it in. How much flight activity is going on at your local airport? When I first purchase an airplane in ’83, I had to sublease a tiedown at a premium from an FBO. Today, at the same airport there are probably 200 airport tiedowns available and you can put your plane in a hangar today.

    Additionally, everywhere you turn there are obsticles to flying: high fuel prices, high insurance cost, high maintenance costs, increased regulation, and overburdensom health reporting demands by the FAA medical certification divisions. For all these reasons, pilots have ceased flying and prospective pilots are discouraged from becoming pilots.

    With fewer pilots, there is less flying and less demand for fuel. We are in the middle of the downward graveyard spiral ending in the demise of 100LL.

  8. JC
    JC says:

    Mr. Zimmerman and everyone else who authors “aviation NEWS” —

    PLEASE STOP writing about “news” that’s at least 5 years old on this topic. There are countless “writers” who are making a career out of this topic by simply repeating news-less drivel about what’s NOT happening – writing about progress that’s NOT being made. These same “no progress, lots of meetings, we’re still talking” diatribes are useless. Why waste the column inches? $73 million dollars estimated over eleven years… does anyone believe this? Dare I say h@ll no —

    Authors have the bully pulpit yet refuse to lead the charge – they just repeat “lack of progress, lots of juice and doughnuts meetings with the alphabet soup groups, nothing new from the FAA” bylines and call it “news”… Another sad example of wasted space…

    It’s called “news” for a reason – please report “news” – aka PROGRESS!

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