RIP: Will 94 UL be DOA?

Here is a thought experiment about the future of avgas.  The conclusion is fairly obvious if you do the numbers: The US consumed somewhere around 135 billion gallons of auto fuel in 2009.  The last annual figures I have are for 2008 at about 138 billion and declining. General aviation consumes less than 300 million gallons of avgas. The last annual figure I have is for 2007 and is declining.

Therefore it appears that avgas represents less than 1/4 of 1% of the gasoline consumed in the US.  It makes you wonder why the refineries even bother, especially when you consider they have to deal with Tetraethyl Lead (TEL) and then distribute the product with special processes so that it doesn’t contaminate the unleaded gasoline infrastructure, which means they certainly don’t distribute it through pipelines, the cheapest transport method.

One other fact that should be kept in mind about avgas:  A number of sources (mainly AOPA) maintain that 30% of the GA fleet has to have 100LL and uses about 70% of the 100LL consumed, while 70% of the GA fleet consumes about 30% of the 100LL — and most of them do not need it — they could be using 91 AKI premium unleaded auto fuel under STCs.  These figures go back to a survey done about 2003.

One should also keep in mind that only about 3% (123 out of 3,658, according to AirNav) of the FBOs in the country sell unleaded auto fuel on an airport and the number is declining. This is a very important statistic affecting the future availability of 94 UL. Ever get the feeling that everything about GA is declining?

Keep in mind that there are already two published unleaded avgas specs: ASTM D6227 for 82 UL and ASTM D7547 for 91 UL.  The 82 UL spec has been out for more than a decade and is in its fourth iteration. Have you ever seen any 82 UL on an airport?  It would work in every EAA STC’d aircraft and Petersen low compression STC’d aircraft.  We could have been using an approved unleaded avgas for more than 10 years in tens of thousands of airplanes and blunted the criticism of GA by the environmentalists for being the last elitist users of leaded fuel.

Sometime this year the ASTM spec for 94 UL avgas will be approved. But so what?  Who will order it? There is no place to put it, except for maybe those 123 FBOs that have a mogas tank.

Just think about it: Avgas represents less than 1/4 of 1% of all of the gasoline produced and there will be a new avgas spec that will work in 70% to 80% of the GA fleet that represents less than 30% of that 1/4 of 1%. On top of that, there is no airport fuel infrastructure to deliver it to airplanes. Who in their right mind is going to produce it?

And don’t tell me that some FBOs will abandon 100LL and sell 94 UL out of their single tank.  They are going to give up the fuel that represents 70% of the avgas consumed? And when a big bore commercial operator pulls up that needs a large quantity of 100LL in one order, are they going to say, “sorry, we only have 94 UL now?” In your dreams.

Can you now figure out why 82 UL went nowhere and nobody even talks about 91 UL?

However, I will offer one solution. Take a page out of the ethanol producer’s manual: Let the taxpayers pay for adding fueling infrastructure to our public use airports.  Ask for subsidies and tax credits.  The ethanol industry has gone hat in hand to state legislatures and Congress for more than 20 years asking for handouts for an energy source that can’t make a profit without subsidies and tax credits. It is currently begging for larger tax credits for tanks and pumps to pay for infrastructure upgrades to service stations for E85 and intermediate ethanol blends like E15 and E20. Type “ethanol tax credits for pumps” in Google and peruse some of the 125,000+ hits. Click here to see how it is done by the masters.

Why didn’t the general aviation alphabet groups ask Congress for airport infrastructure tax credits when Congress was debating the economic stimulus package? Congress was dying to throw money at infrastructure projects, yet the aviation alphabets are letting our GA airports die a slow death.

What is most amazing is that they are betting the future of avgas on a single unproven new fuel process proposed by two tiny companies, Swift Enterprises and Virent Energy Systems. Their products are known as a Binary Unleaded fuel.  There is no clear indication how long it will take to prove that the product can be made by a commercially viable process and be approved for aviation use and put into production and distribution. However, we do know that TEL will go away.

Of course, if the new fuel doesn’t prove feasible, we can put the 94 UL in the empty 100LL tanks after the refiners ramp up production. With the present slow decline of GA, I’m sure nobody will notice.

Dean Billing

The GAfuels Blog is written by three private pilots concerned about the future availability of fuels for piston-engine aircraft. They are:

  • Dean Billing (Sisters, Ore.) – an expert on autogas and ethanol
  • Kent Misegades (Cary, N.C.) – an aerospace engineer and aviation journalist
  • Todd Petersen (Minden, Neb.) – former aerial applicator and owner of more than 150 Mogas STCs for aircraft

For a list of airports that have ethanol-free fuel and those no longer pumping it, compiled by the authors, follow this link.


  1. Karl D says

    As long as 100LL is around, very few people are going to bite on the 94UL. Aircraft operators know 100LL works in their engines, 94UL or any other alternatives have not proven themselves to work well in our engines for the long term. While pilots are still using the current fuel, no fuel station is going to switch to an alternative fuel. So unless the alternative fuel is much cheaper than the current avgas or 100LL is forced to go away by government mandate or a business decisions by the fuel companies, leaded avgas will be around for awhile.


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