Airports will have an easier time switching from 100LL to unleaded 100-octane fuels thanks to a last-minute amendment to the 2023 FAA Reauthorization Bill. The bill was just passed by the House and awaits Senate review no sooner than September. Original language in the bill, carried over from the 2018 bill, appeared to require airports to continue selling the same leaded fuels they offered in 2018 without respect to switching to unleaded avgas.
California Rep. Jay Obernolte, who offered the amendment, explained the legislation in this video interview. He said airport operators were complaining that to sell unleaded fuel, they would have to install additional tankage or trucks, which few airports can afford. As currently amended, the bill allows airports to switch to unleaded fuels as long as the fuel is approved under an industry consensus standard. That generally means a spec provided by ASTM.
There currently are no 100-octane ASTM-spec fuels, but Rep. Obernolte told AVweb that he thought an industry-consensus fuel could emerge within a year or two. The only FAA-approved 100-octane unleaded fuel is G100UL, developed by General Aviation Modifications Inc. It’s approved by the FAA under STC, but does not have an ASTM spec.
What was the problem with the STC-approved fuel? “Only that people have to buy [the STC],” Rep. Obernolte told us in this interview last week. Obernolte is a pilot and flight instructor and has served in airport boards. “That’s why we put the language in there requiring an industry consensus standard, because if you are going to require someone, maybe a transient aircraft … and the only fuel available is one that requires an STC, you’re going to require them to buy the STC to fuel that aircraft. That could be a problem,” he added.
GAMI’s George Braly said that the consensus standard requirement would complicate if not stop dead its efforts to begin developing a market for G100UL. Although Obernolte says the amended language is an improvement, Braly said under its terms, airports would still need a second tank or truck if the fuel lacked consensus approval.
The FAA has restarted its Piston Aviation Fuels Initiative (PAFI) testing program and is currently examining two fuels, one from Phillips/Afton and a second from Lyondell/VP Racing. It’s unknown when, or even if, PAFI will disgorge a drop-in fuel. The previous iteration of PAFI conducted testing for four years and failed to find a suitable fuel. If one or both current candidate fuels prove suitable, they will still have to wind through a separate process for an ASTM consensus standard.
When asked why a consensus standard was necessary, Obernolte said it would make fielding the fuel more efficient. “The number one concern we have is that it’s widely available to everyone. We want to make sure everyone is able to use that new fuel and that’s why we require a consensus in the industry that that fuel is a replacement,” Obernolte said. He concedes that the amendment doesn’t give GAMI a clear path to fielding G100UL. “The barrier was higher before the amendment because no airport would be allowed to switch at all if they only had single tankage. It might not be everything GAMI wanted, but it’s certainly better than the language was before,” Obernolte said.
Also in the bill is a provision requiring the FAA to launch a study to eliminate delays on designated pilot examiners administering practical tests. Because of a shortage of DPEs, delays in scheduling checkrides of up to a year have been reported. The bill would require the FAA to reduce that to no more than two weeks.
“I think they will need more DPEs. DPEs aren’t something that necessarily costs the FAA a lot of money. A DPE, by definition, is not an FAA employee,” Obernolte said. “The first thing that needs to be done is to create a plan for getting it done. And that’s what we’re requiring the FAA to do,” he added.
They need to develop a market for 100ul fuel? Isn’t there a market in place already?
As long as the octane levels are the same as what’s currently available, I don’t see an issue. It’s when the octane is lower, there’s a problem.
I would hope by now all the current aircraft flying have the hardened valve seats, better valves and valve guides installed.
The vintage aircraft flying, there might be issues. But I seriously doubt there’s that many that haven’t been upgraded. And if they haven’t, there are lead additives available. Just like when the phase out happened to the automobile applications.
Lead in fuel has nothing to do with valve seats, valves, or guides. That has been a persistent myth for decades.
It’s an octane buster only.
NOn hardened valve seats wear rapidly on unleaded fuel. this is due to a lack of leads lubricative properties. there have been many studies on this since the 1960s when lead was first proposed. . A friend had this issue on his pontiac 413 GTO engine and installation of stellite seats solved the problem IF this was not an issue stellite seats would not exist.
ALso this is a common first year subject in combustion theory that is a required course on most Mechanical enginerring classes.
Automobile engines are not aircraft engines. Lead was added strictly for boosting octane, nothing more, any additional effects were incidental.
Hardly many studies. Some studies would be more accurate. The big one was done by Phillips. They claimed lead lubricated to the extent that it prevented microwelding of the seat and valve surface. Wasn’t well documented, however.
https://www.youtube.com/watch?v=ovJBJjZTjsk
That’s not true. I personally took car engines apart that ran on leaded fuel. After a complete cleaning, the exhaust valves were still in specs and reusable.
I then took apart an engine that ran on unleaded fuel. All of the exhaust valves were pitted. So badly, none of them were reusable.
I am not advocating leaded fuel. I am just stating what I found.
GAMI was never going to convert single pump airports to G100UL if 100LL was still legal to sell since 100LL was going to be significantly cheaper. This bill doesn’t change that. G100UL needs a rollout strategy which doesn’t rely on using the only airport pump. If they can’t find one, then that explains why, almost a year after it is approved, there is not one single G100UL retail pump anywhere in the world.
Meanwhile, Swift UL94, which also has an STC, has at least 36 pumps and counting and is generally sold along side 100LL where offered.
Despite what Paul says, the language does not require sales of leaded fuel, it only requires sale of a universally usable piston fuel if the airport had one in 2018. Switching to G100UL entirely would qualify since it is universally usable. The language gives the FAA leeway on how to interpret that since the penalty for violating this section is entirely up to the FAA.
Any unleaded 100 octane fuel will require SOME changes, at least some sort of supplement to deal with density and other changes in characteristics. So planes can’t simply just show up and use any unleaded fuel without some preparation.
Mike C.
G100UL is *not* universally usable as entire categories of aircraft are not approved under the STC. (All rotorcraft, for example).
I operated my 1931 Ford Model A on unleaded fuel for thousands of miles as have thousands of other antique car drivers with no valve problems. Think about it, when many antique airplanes and automobiles were the daily drivers and flyers there was no leaded fuel.
No one is willing to make ethanol free MoGas available at airports.
I would have stopped using the darn 100LL some 20 years ago but my MoGas STC is useless when E-0 MoGas is not promoted or available.
I agree. UL94 is also a great product and DOES NOT require an STC in many of our aircraft. We need more gasoline sold at airports that has no lead and no ethanol.
Why was the ADS-B mandate able to be met, but an unleaded fuel mandate is a non-starter? Everyone (virtually) had to buy an ADS-B unit. What’s wrong with requiring an STC, especially if the FAA subsidized it?
Requiring an STC for fuel is that unlike a single equipment mandate like ADS-B, set to a TSO standard, Fuel is an expendable commodity. If we were to permit the STC route, multiple STCs for fuel would be required for each manufacturer. Already Swift and Gami are requiring STCs, GAMI for all comers, Swift for some. Mogas STC is available for all fuels meeting the ASTM standards which sets it in a different category than a manufacturer specific fuel. Monopolies always favor the monopolist and not the consumer. Brayley states that the pending legislation will interfere with his marketing campaign. It will. It will force him to submit his fuel for ASTM qualification something he does not want to do, instead charging each aircraft/engine a license fee (STC) on top of the substantial price premium to use his fuel. Imagine if that were true of Exxon, Phillips, Avfuel, Marathon, Shell, each charging a large STC fee to use their fuel at a price of their choosing on top of the per gallon price? It’s unworkable. Then imagine a small reformulation requiring a new STC.
The explanation that I read for valve problems had nothing to do with the supposed lubricity of lead but was caused by lower octane ratings. When tetraethy lead was being used to increase the octane rating, it was common to have an actual octane rating higher than the stated octane rating. With unleaded fuels, it became more expensive so more effort was put into having actual octane rating closer to the stated rating which caused detonation in certain high performance engines.
George needs to get his G100UL into PAFI or his investment might come to naught. Alternatively, since the FAA says it works in “all spark-ignition engines in the fleet”, they could buy him out and put the formula in the public domain. Done.
All of the King’s horses and all of the King’s men…… The problem is not the fuel or the engines the problem is the $$$$$$$ that is always the issue with any product that is marketed to the general public. First they said they would “study” 100UL fuel. Blah, blah. Years later, bureaucratic floundering and much $$$$. Nada! Why? because those who were making and selling 100LL didn’t see a profit. So GAMI calls the industry on their game and produces a product that can be used by GA aircraft. Oh no! And so it all goes open loop with more excuses and another useless bill. I have a modern 130 HP air/oil cooled fuel injected aircraft engine that runs on 91UL pump gas. No knocking, full FADEC (gee only a power lever and no “lean of peak”) ECU and sensors makes it very efficient and reliable. Burns 4.5 gph at 9500′ and 5gph in the lower altitudes. I can swing by Circle K and Gerry jug it to my hangar and my plugs are clean, engine runs smooth. Mogas would be great but we don’t have Mogas at our airport and I have only seen one airport in California (on a X-country) that had it. So I have to pay $6/gal for 94 octane fuel that has lead which makes it behave as it it were 100 octane fuel (100LL). When they can make more $$$$ selling 100UL then they will stop making 100LL. Simple economics. Meanwhile politicians and mfg’s waving arms and barking.
Does anyone remember WHY UL Mogas (supposedly) doesn’t work in aircraft? After over 40 years, this avgas is more General Horsepiddle + As The Stomach Turns + Guiding Blight DRAMA. Nothing more, nothing less. I suspect that UL Mogas would actually work in all aero engines, with octane boosters as needed. Put an electric fuel pump in /near the tank and vapor look problems go away. Use auto tech, it’s been developed and tested by millions of new engines every year.
But NOOO, we must spend billions reinventing the wheel…