In my last column, “Birds of a feather,” I wrote about the need for an ASTM standard for any new unleaded replacement for 100LL.
I also noted that a committee has been working on a new specification for about 25 years and ASTM is now looking at issuing a separate spec for each individual fuel manufacturer.
I have received several questions from readers asking what the difference is between an ASTM spec and qualifying a new fuel using an STC.
The problem with using an STC is that after 100LL is gone, pilots who are flying cross-country and land at an airport that is supplied by only an STC qualified fuel will not be able to purchase that fuel if he or she does not have the necessary STC.
I feel that it is important that all new unleaded replacements for 100LL be ultimately approved for all applications by all active manufacturers.
An STC approval may work for a start-up, but by the time 100LL is fully eliminated, the replacement products need to be qualified against an approved standard. This standard (or standards) need to be acceptable and agreed upon by all parties, including the FAA, the engine manufacturers, and the airframe manufacturers.
The most common suggestion I have received concerning the future of unleaded avgas is that there is a need for two grades of fuels, not just one.
Most pilots feel that there should be a new 100 octane unleaded fuel to replace 100LL and a second grade for either an auto fuel-based product or a 94-octane fuel based on just removing the lead from the current 100LL. (Swift Fuels already has a fuel, UL94, that meets ASTM D7457.)
In the 1990s, the man in charge of fuel requirements at Cessna, Cesar Gonzalez, felt that the future of general aviation — and especially sport aviation — rested on the availability of a non-boutique fuel derived from the readily available pool of automotive gasoline.
That led to the development of ASTM D6227, “Standard Specification for Grade 82 Unleaded Aviation Gasoline.”
While the spec had limits on ethanol and other oxygenates, it was basically just regular unleaded auto gas.
The spec was approved by ASTM, but I believe is not being used at this time.
I suggest the industry and regulators, including those involved in the Eliminate Aviation Gasoline Lead Emissions (EAGLE) initiative, work to get the 82UL spec active again.
Then the members of the General Aviation Manufacturers Association (GAMA) could approve the fuel for all 80/87 engines in the fleet, plus all of the sport aviation aircraft.
Next, the National Air Transportation Association (NATA) could encourage all FBOs and fuel distributors to make the fuel widely available.
Many FBOs already have the facilities to handle two grades of avgas, but others may need to add some equipment.
The big problem here is sourcing non-ethanol auto fuel. However, auto fuel containing ethanol cannot be shipped in pipelines. This means that non-ethanol fuels are available at all distribution facilities even if a state requires that all auto fuel contain ethanol.
Once 82UL becomes available and pilots become aware of it and know that it is approved for their aircraft without an STC, I believe that the sales and benefits will become very significant.
For example, the economic benefits for pilots will be very real. According to a recent Google search, the average price for 100LL in the US in early October 2023 was $6.93 per gallon. The estimates for one of the 100 octane unleaded fuels say it will cost between 50 cents and $1 more a gallon than 100LL.
However, the present price for regular unleaded auto fuel is about $4 a gallon vs $7.50 for an unleaded 100 fuel, saving pilots about $3.50 a gallon.
If a pilot flies 100 hours a year at 8 gallons an hour, that is a significant difference, especially for working class pilots who just want to go for a $100 hamburger and not a $200 hamburger.
There will be some additional costs with 82 UL fuel, such as handling and shipping, plus storage at dedicated facilities.
However, these can be offset by refunds of road taxes. If an auto fuel is sold for a non-road use, such as in aircraft, the state and federal road taxes can be refunded.
The bottom line
Approving 82UL is not the total answer and it is not the grandiose solution for all of GA’s unleaded fuel problems. But it will help ensure a continued supply of an approved, reasonably priced fuel for part of the GA fleet.
And it will significantly reduce the amount of lead being emitted into the atmosphere, which is one of the goals of the EAGLE program.
The other option is to do nothing and wait for a fully approved unleaded replacement for 100LL.
But based on past performance, how long will that take? And how will that affect the costs associated with flying a GA aircraft?
Take that one step further: How will that wait and uncertainty affect the number of people going into or even staying in flying?
The small volume production of 100LL makes it bad enough, cost wise. Make two versions of unleaded will be worse for everyone. Smaller volume means higher price to make and more hardware (transport, tanks, pumps) to support.
We need ONE solution that works for all of us.
Unfortunately, Ben is contributing to the confusion around the unleaded avgas development process rather than cutting through it for us. Ben seems to have adopted the view that if there’s an ASTM spec, then pilots won’t need an STC to use the fuel. But that’s not the case. For instance, Swift’s 94UL is available today, there’s an ASTM spec, *and* you need to have Swift’s STC to legally use the fuel in your airplane. The FAA has said some similar paperwork will be required for any new unleaded avgas, including all the ASTM specified ones.
Ben also claims that GAMI has forgone the spec process in developing their G100UL fuel, but that’s not the case either… GAMI just chose to have a private specification, as specifically allowed by Federal regulations, rather than attempt to work through the ASTM process. GAMI’s specification even looks just like an ASTM specification. Ben said ASTM has been working the issue for 25 years. Actually, the effort began in 1991, so that’s 32 years now. And Ben wonders why GAMI didn’t want to hitch their wagon to that star?
Ben and Jack Pelton are also misguided when they complain that folks don’t know enough about the STC’d candidates (GAMI’s already approved fuel and Swift’s 100R still in the STC process). Yet, GAMI’s and Swift’s patents are available online, and GAMI at least has offered full access to engine and air frame OEMs to all the details, including their specification. Some have taken them up on that, others are hanging back. Given all that, we know more about the STC candidate fuels from GAMI and Swift than we do about the FAA PAFI candidate fuels from Phillips/Afton and Lyondell/VP-Racing.
The question here isn’t whether a specification is on ASTM stationery or not; the question is whether someone has developed a fuel that works and is FAA approved (Hint: GAMI is already there; the others may come along later) and whether the OEMs will spend the time and money to understand these new fuels and get comfortable with their applicability to the fleet. Lycoming’s Jennifer Miller at Oshkosh opined in her forum session that we’ve had leaded fuels for decades, and we’ll have leaded fuels for years to come. So why should Lycoming spend time and money understanding unleaded fuel? That strategy seems likely to backfire in view of the EPA’s lead endangerment finding and the host of local efforts to outlaw leaded avgas sooner than EAGLE supports.
If there’s pressure to be applied, it’s not on GAMI to retrench and participate in a hide-bound, conflict-ridden ASTM process. It’s instead for the OEMs that haven’t already accepted GAMI’s invitation to come understand the fuel to disabuse themselves that we’ll have leaded fuel for years to come.
It would be nice to see UL94 as a second option at all airports. If that was offered I think a lot of the aircraft that need 100 octane fuel would probably start the process to modify them to use the 94 UL. There are many advantages to using the 94 UL like more time between oil changes, no lead fouled plugs, possibly increased TBO and lower cost of the fuel when the demand increases.
There has never been a problem with any kind of gas for either cars or airplanes, the big problem is and has always been, and will continue to be, how much can us pilots get ripped for and continue to do for ever more. That is all this alleged hoopla is, The gas mfg. company’s know this will probably be the last round up as far as ripping off the customer before it all comes to a standstill, So they all got together and are trying their best at charging as much as they can get away with before it will be all over. After that happens we will never hear any more about 100ul or any other kind of fuel. Once everybody gets exactly how much they want, it will all end. That’s all this is about. In the past it only took a few months to change anything to do with fuel, but now that they can steal more money and not be questioned about it, that is what is going on, nothing more, a lot of words continue to be written about this that and the other, just smoke and mirrors.
When 80 octane avgas was phased out in the mid-late 1990s, those in the engine overhaul business struggled with the use of 100LL for break-in and normal operation of small, low compression engines. 80 octane fuel was a relatively fast burning, low-leaded fuel just right for Continental O-200 and O-300 engines as well as some 7:1 Lycoming versions of the O-320. The red fuel often did not have the lead it could have but seldom, if ever, went over the 0.14 g/L max Pb allowed. Eliminating the fuel and mandating one-size-fits-all 100LL gas was a compromise that did not work, especially with elevated lead content four times that of 80.
There’s a great deal of history here and absolutely no need to re-hash the anecdotal evidence in support; the fact is hot, slow burning 100LL scorched exhaust valves and guides and stuck valves in these engines with no avenue for alternatives. Consequently, some engine rebuilders were fine with the use of no-alcohol auto fuel just to speed up the combustion process, thereby lowering EGTs and reducing valve sticking. Owner/operators have figured it out, too.
No one wants two fuels and the FBO investment recovered at your expense, but engine guys know one size-does-not-fit-all for some engines.
Let me do some figuring: if I can control of my fire-breathing 550 engine to the point that it would start pinging, but keeping the MP, could the engine servive?
And since I have either turbos or a blower to keep MP under control, couldn’t I keep my low compression happy? In other words, I can control my low-compression engine happy.
It’s ridiculous that environmental crazy people think the miniscule amounts of lead in aviation fuel is a threat to public safety. It’s NOT! They are forcing the aviation community to spend untold amounts of money and creating problems for no good reason.
Interesting article but given the costs to the FBO’s of carrying two grades of AvGas, the only practical way out of this mess is to approve the universal use of a direct 100LL replacement across the board. The real elephant in the room here is the lack of economic incentive to make the transition happen, as the consumption of AvGas is so tiny in comparison to other refined products. If the economic incentive is not enough, maybe the shuttering of more and more local airports over the lead issue (red herring or not!) will be the motivator – a la Reid Hillview just up the road from me. For many of us, the fallback to MoGas is not possible – there is no ethanol-free car gas within a 100 miles of my home base at Salinas. FYI – just paid $6.39 for 100LL yesterday – only a dollar more than the cost of premium unleaded at the pump (I know it’s CA – what can I say).
I believe, SWIFT has said publicly that 94UL will no longer be produced once they have their UL100R available
These are good points well presented. I find it unfortunate that one would propose such a low AKI when so very many of the most common aircraft and their engines (think most engines above 100hp and below 200hp) require a higher AKI. That higher AKI, governed by engine compression ratio, typically is around 91. Lycoming, for example, has produced a document which, in its broadest strokes, states that most of their engines with a compression ratio of 8.5:1 or lower are good to run on less than 100LL. If one examines the GA fleet this cutoff point would satisfy a huge percentage of the fleet.
Setting the cutoff point at an AKI in the 80’s still leaves a very large portion of the fleet hanging in the wind. It would seem to make much more sense to target the broadest market, that is to say, the market in the low-90’s AKI range rather than setting our sights on such a small portion of the market which requires an AKI in the 80’s.
As for inexpensive pumping equipment, frankly, that’s an area where the author should do considerably more research before formulating an opinion. Often it’s not the pumping equipment that’s expensive but rather it’s the attendant credit card billing machine that’s hugely expensive. Our airport badly needs to update its billing machine but the costs to do so are prohibitive (north of $100K by the time it’s actually up and running).
There’s another aspect to this proposal which merits much deeper consideration. Our experience has shown that vendors of automotive gas want nothing to do with delivery to an airport where their liability exposure skyrockets. We can’t even get the local fuel supplier to deliver diesel to the bulk tank for our runway maintenance equipment because their insurer won’t allow them to operate their delivery trucks on airport property.
The author has made an interesting argument but it’s one which reveals his research into ALL aspects of the proposal has not been thorough. Do the research on the supply chain and see if there’s a way this “second fuel” can be made to work at a price and volume point that’s attractive to both airports and pilots.
By the way, I’m the guy who fuels his three airplanes from jerry cans filled with 0% ethanol car gas so I’m already a convert to a “second standard” for aircraft fuel. In fact I’ve purchased precious little 100LL since about 2005 – I only buy it when I’m away from home base and have no alternative.
Mark, I sold the great fuel systems from U-Fuel of Wisconsin for some years. They offer low-cost, turnkey, multi-fuel systems with low-cost credit card capability. Larger GA airports allow the big Avgas suppliers total control over fuel decisions and equipment. Therefore getting Mogas onto airports will be easier on privately-owned airfields. One could haul E0 mogas from a gas station, but better is to buy it at a fuel terminal. There are thousands of mom-and-pop fuel haulers out there. Call around until you find one willing to do it. In areas with larger Amish populations this is more common as the Amish prefer E0 fuel in their generators. As far as engines are concerned, we studied the entire US piston aircraft fleet a few years ago and found that for 70% of them, low-cost Mogas STCs already existed that required no modification of the aircraft or engine. Note too that the world’s largest aircraft engine manufacturer, Rotax, recommends E0 mogas as the ideal fuel for their engines. Another expensive, universal, boutique fuel only needed by a small percentage of the piston fleet may solve a problem for those with million-dollar aircraft, but it will only cause the continued decline in sport aviation. Note that gasoline costs under $3 again in the Carolinas, so E0 prices are also significantly lower than Avgas.
Kent – what constitutes “low cost” for a fully independent fuel dispensing system? Is the U-Fuel system approved for use in Canada? What are the recurring billing fees for use of the U-Fuel credit card processing? We’ve been struggling to find anything that is “low cost”, either for up-front capital costs or for recurring costs.
Thanks.
So what if you don’t have the STC and you just fill up anyway and split?
I hear that you have to put your STC number in the pump that supplies the 94ul to get the pump to turn on. So no fuel and run will not work.
Way back when we were losing 80/87 I ran an FBO in NH. Through a family connection I was invited to lunch with the VP of transportation fuels at Mobil. The real takeaway from that meeting was that ALL OF AVIATION FUELS were only 3% of his transportation product. That meant that the small volume of 80/87 was just a small dot on a big board. If you move that fwd to today with the recip freighters gone and most corporate on jet fuel the idea of two aviation fuels is hardly in the best interest of anyone but us the pilots.
My home field is undergoing the process of replacing its current fuel farm with a new one. A “cheap” system is necessarily small, which means more deliveries per year resulting in a much higher per gallon cost. A system capable of taking much cheaper bulk load refills is very expensive, like $500k expensive including removal of the old one and site prep for the new. Besides simply costing twice as much, a two-pump “solution” divides utilization per tank by two and doubles the cost paid for fuel delivery.
It’s not as simple as it might seem.
Ben, nicely articulated! The only problem I see is a government agency understanding your sensible logic.
Wow, back to the future. Tod Peterson and others advocated for this decades ago. I wrote about it for GAN and the EAA. The EAA then was pressured by the big Avgas makers and my work was censured by EAA publications. When I visit with flying friends in Germany and Switzerland annually, I note that mogas is available alongside 100LL, diesel and Jet-A even at small GA airports. See Pure-gas.org for a list of 16,772 gas stations that sell ethanol free fuel. Not all have the AKI levels we need, but many do. They all get their fuel delivered from fuel terminals, which, as this article mentions, will always have ethanol-free, high octane gasoline as ethanol and ethanol blends may not be pumped through pipelines due to its corrosive nature. Thanks Ben for stating the obvious. Do not expect the aviation alphabets to pay attention to this common-sense solution though.
I hereby nominate Ben Visser for the office of President of the United States!
He is the only person making any sense at all of the no-lead fiasco. BUT it would require TWO PUMPS + Jet A and he will surely get a lot of HEAT from that.
There are plenty of low-cost fuel systems available. If airports thought more like entrepreneurs and less like government bureaucrats, they would see a business opportunity here. Let private individuals supply the fuel system and deliver the fuel. Charge a small fee and everyone is happy. Airports should do the same with hangars – let private people and companies build and operate them. That would end the widespread shortage of hangars. Government airports look at funding though through the lens of bureaucrats, seeking government funding, which can take decades.
I would love to see a list of low cost fueling system suppliers. My home airport is having problems even getting anyone to bid on replacing our old, always breaking down system. Right now we have 2 tanks, 100LL and Jet A. The Jet A is dispensed by truck only leaving the pumps for 100LL.
But hey I have the mogas STC and get my non-ethanol at the corner gas station. Had to pay $3.65 a gallon last week!
Many Airports already do the hangar thing — You build it and 20 years later, the airport owns it (or whatever the “agreement” says). Oh, and in most cases I know of, you also pay rent for the ground you are using.
In some cases there are people who have built private hangars off airport property with a right-of-way “easement” or something to that effect. And then the owning agency of the airport wants to tax you for entry via the taxi-way that was built, because you need to pay your fair share….. And what do they charge transient aircraft? Well they buy fuel. And so do the ones just off the airport. Some of this gets to be nothing but a money grab in my opinion.
The argument dismissing STC approved fuel is exceptionally weak. And this argument forms the basis for the rest of the article. Acquiring an STC is not difficult – nearly all aircraft have purchased one or more of these for various purposes. Acquiring an STC for a fuel which actually works (currently the ONLY fuel which is a universal and safe substitute) is trivial.