Search for 100LL alternatives continues, but slowly

The AVweb staff recently put together a comprehensive update on the search for alternatives to 100LL, detailing the latest from Swift Fuels, General Aviation Modifications Inc.’s G100, as well as the search for a drop-in, direct replacement for tetraethyl. The report notes that development “continues apace, although no clear winner is in sight.”  Check it out here.


  1. says

    Car fuel, which is a massive market of more than 130 billion gallons in the U.S., is unlikely to be influenced by a very small aviation community seeking fuel in quantities in the millions of gallons. Moreover, the biofuels community in the U.S. produced an order of magnitude more ethanol – and other fuels – last year than general aviation burned in total. So market economics are heavily unfavorable when one considers why the motor fuel industry, which is already at E10 and climbing, should care about a niche fuel outside of its market spectrum, which is what aviation fuel is. And that is excluding considerations like litigation. For E0 mogas to be used more generally in place of Avgas, general aviation would be wise to set up its own regional or even local supply chains for aviation mogas and not be dependent on fuel supplies with economics optimized for motorists. It should still be less costly than Avgas. An alternative is for the general aviation community to invest in aviation biofuels. Advanced biofuels facilities scale perfectly for general aviation’s market size and the aviation community wouldn’t need to compete with fuel supply chains optimized for motorists.

  2. says

    I note the article in the Jan. 24 issue of AVweb, “Fuel Projects Move Forward, But Slowly,” and I appreciate the reference to mogas in the article; however, I would like to clarify and expand a couple of points.

    The price differential between mogas and 100LL is far greater today than it was in the 1980s, not the other way around. And it is the addition of ethanol that has thrown a wrench into the works insofar as the availability of mogas is concerned. Auto gas has not fallen out of favor; it’s been contaminated.

    While indeed there are fewer airports selling mogas today than in the late ’80s, the reason for that is the EPA regs that forced the removal of underground tanks in the 1990s — not because there was inadequate demand, not because it had “fallen out of favor.” What are lacking today are reliable sources of non-ethanol gasoline.

    Then there was this statement:

    Another option on the table, albeit not an approved aviation fuel, is mogas.

    Statements like that are what hold back a wider acceptance of mogas, and we’ve been battling that same negative attitude for years. Once it is placed into a properly STC’d airplane, autogas becomes an approved “aviation” fuel. It is viewed that way for tax purposes by the individual states and by the federal government. In the 1980s, the FAA viewed it that way as well. You may call it what you will, but the fact remains that auto gas has been in use legally since 1983. Thousands of pilots have saved literally millions of dollars by switching from 100LL to auto gas. While the fuel itself may not be “certified” as avgas, engines that burn it are — by virtue of the Supplemental Type Certificates that approve it.

    A great deal of the hand wringing over a drop-in replacement could be avoided if our airports were able to order up premium unleaded E0 mogas rather than waiting another 11 years for Swift or GAMI. If the alphabets had been doing their job properly, then they would have made at least some effort to keep premium mogas ethanol-free when the ethanol mandates were being codified. Doing nothing, however, allowed auto gas to fade away without anyone having to lift a finger to make it happen, and the only thing left would be some vague promise of a drop-in replacement — eventually.

    Then there is the notion that our highest-powered aircraft cannot use mogas, which is blatantly wrong. I continue to maintain that 99% of the high-powered end of the fleet could use premium mogas with an anti-detonation injection (ADI) system making up the octane deficit in the higher-powered airplanes.

    Keep in mind what has happened just in the past couple of years. The new LSA class have type certificates that approve autogas as well as the latest generation of engines for these aircraft — Rotax, Jabiru, I0-233 and others. See see this link for a list.

    The latest generation of AF (alternative fuel) engines from Continental and Lycoming are designed to operate on certain grades of mogas as well.

    Finally, the world’s largest producer of light aircraft, Tecnam, has an “all mogas” policy for all their aircraft, including the new 11-seat, Lycoming-powered P2010, certified from day one to operate on mogas.

    This demonstrates that many of the leading manufacturers of engines and aircraft are of the opinion that auto gas will play more than a minor role in what is to come. They are building airplanes and engines right now, today, which will burn unleaded auto gas. If anything, many in this industry are of the opinion that a drop-in replacement will play a non-existent role in the fuel transition. These companies clearly are not waiting another decade for someone to produce a new fuel.

    Todd L. Petersen

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