I’ve had this idea for a while now but it just never seemed appropriate to float it. I think there should be two garage sales, one in Ada, Oklahoma, and another in San José, California. Now, I can’t see much interest in the items on offer. I’m not sure who might want some of those cheap foil turkey roasting pans you buy at the dollar store. Likewise for the rubber gloves with pinpricks in one of the fingers, Tupperware knockoff resealable containers and a host of pretty much useless junk that has accumulated in both locations over the past year. Add the fact that all of it has been soaked in gasoline for at least part of that time and you have a big pile of nothing to create a lineup in the driveway at 8 a.m. on a Saturday morning.
But the historic significance of that assortment of Chinese-made housewares is considerable. For most of 2025 it represented the state of the art in the observational analysis of the interaction between unleaded aviation gasoline and the bits and pieces of airplanes it comes in contact with during the normal course of turning dead dinosaurs into aerial locomotion.
In late 2024 an A&P in San Jose named Michael Luvara became aware of some paint damage on aircraft that had started using the newly available G100UL unleaded avgas at Reid-Hillview Airport. There’s no doubt that there were some ugly stains and leakage in a few of the about 100 planes that were using the gas, and Luvara created some fairly dramatic videos showing what may point to problems with the fuel. He used a variety of shop and kitchen items to approximate the real-world conditions of the planes and raised questions that merited answers.
Across the country in Ada, George Braly at GAMI, whose fuel was the object of Luvara’s dripping and bubbling, started up some tests of his own. Beyond some paint discoloration under specific circumstances, he couldn’t duplicate what Luvara was seeing. I ran stories about it in my other life and I wasn’t surprised when the FAA sent some inspectors out to Reid-Hillview to look at the stains and drips themselves.
Now, the FAA has rarely been accused of underreaction but after crawling around under the ugly paintwork on these planes we heard nothing. There was no mention of any threat posed by the fuel and those who hadn’t been scared away from using it by Luvara’s videos continued to pump and burn it.
So imagine my surprise when mention of Luvara’s videos and my small role in getting them into the public eye showed up in the FAA’s highly tentative roadmap for implementation of the 2030 phaseout of 100LL. And I hope what that did was prompt exactly what I was hoping for in that 77 pages of what I thought was timid and butt-covering policy avoidance.
Buried deep in endless paragraphs about all the roadblocks in the way of that now urgent goal was the revelation that the FAA is going to have a fuel smackdown. The three candidate fuels for a replacement for 100LL will be put through a battery of tests in a head-to-head examination of which ones actually work. Between the secrecy of the proponents and the silence of the FAA, it’s been impossible to gauge any progress on this most fundamental factor affecting the future of general aviation. These fuels will be compared side by side in detonation and other engine performance tests, airplane parts will be scientifically dipped in the gas and God knows what else, but what’s important is that there will be impartial people with clipboards recording all the results.
At the end, we should have a pretty good idea what each fuel can and, more importantly, what it can’t do. We’ll also know what impact they have on materials and maybe even human health. Then, we as pilots and operators will be able to figure out what’s going to work for us in our aircraft. I don’t think it will be easy. Let’s consider where we’re starting.
We have three contenders and what we know about them can be summed up like this. One of them says it’s impossible to create an unleaded drop-in replacement, another says they’ve already done it, and another says they’ll be the last fuel standing.
So bring it on, FAA. Maybe even jazz it up. Do the tests in a cage with flashing lights and smoke effects. But for heaven’s sake do it using the finest scientific processes possible so that we as pilots and operators can make the best possible decision on how to fuel our aircraft. It really doesn’t get any more basic than that.
And, in the end, it may be that none of the fuels works as well as 100LL does for the minority of engines that use the majority of fuel, those in the 350-horsepower range. We’ll have the information we need to deal with that, too. Throughout the document issued by the FAA this week is the persistent message that gasoline isn’t the only thing that will get air moving over your wings. DeltaHawk, whose recently certified compression ignition engines have found a couple of OEM customers in recent months, is using the mess over unleaded fuel as a marketing pitch. A Chinese turbine manufacturer says it can build a cost-effective 350-horsepower turboprop. And let’s not forget that the vast majority of weekend warrior aircraft (and a few bigger ones) are perfectly happy on 94 or 91 unleaded fuels minus the alcohol your tax dollars add to car gas.
Maybe the end of avgas as we know it isn’t the end of GA, just the end of GA as we know it.
“…those who hadn’t been scared away from using it by Luvara’s videos continued to pump and burn it.”
That statement is hogwash. I’m on 1 of 3 airfields selling G100UL, and almost no one on my home field uses G100UL. Well beyond Michael Luvara’s videos, we have the ACTUAL aircraft that suffered real damage from the fuel. The airport has 1000 gallons and the airport staff has said no one is pumping it. They have tried to sell it off and no one wants it.
This article reads like a cheerleading squad for this failed fuel.
Russ, I highly encourage you to have a conservation with the Ops team at KRHV and KWVI to hear the local real world perspective.
I have been telling the FAA and anyone else that would listen that the lead needs to be replaced by finely ground iron or copper or a combination to cool exhaust valves. Iron is non toxic, copper in small amounts is non toxic. So why this has not happened is mystery to me. People need to think terms of additive replacement and have not. Having flown a C-172 on unleaded auto gas in the 1980s and burning two exhaust valves 200 flying hours apart, I have first hand experience with unleaded auto gas. The EAA and Peterson STCs require adding oil to the unleaded gas; evidently to cool the exhaust valves. But no one has said this. So, it appears three choices exist: a small amount of: oil addition; or finely ground iron addition, or finely ground copper addition to unleaded gas to cool aircraft engine exhaust valves. Seems like a no brainer to me. But no one so far has followed, what I consider, logical thinking. I personally do not trust the oil addition; thinking it will not be evenly distributed. But do not know for certain. During the 1980s, I thought adding oil to unleaded avgas was a waste of time; which it probably is not. On unleaded avgas, I noticed a high pitch very repetitive clacking which was not there on leaded avgas. Suggesting to me, in addition to cooling the exhaust valves, lead smooths out the running of the aircraft engine. Or, there is more to this than meets the eye. And I believe iron or copper is a sufficient substitute for lead plus being non toxic will solve the valve cooling problem and the engine smooth running problem without the lead.
“… but what’s important is that there will be impartial people with clipboards recording all the results.”
Ha! That seems unlikely. These will be the folks that have been bringing you PAFI and it’s complete failure to produce for the past 20 years, right? “Impartial” seems… optimistic…
As a pilot, aircraft owner and lifelong turbocharged race car guy, with 5 decades of high octane, high boost capable fuel experience, I know this is no simple matter. First, there has never been a non oxygenated unleaded fuel that can match 100LL’s relatively modest overall capability. Toluene in high percentages can provide adequate detonation resistance under very high boost, but is god awful to deal with on cold startup and at low power settings. It’s no answer. Swift’s orig binary fuel, UL100 was Trimethylbenzene and Isopentane. It provided adequate everything except the ability to start engines below 50ºF. I speculate that a ‘part time’ very high energy ignition system would be required to make that fuel work. Much like a turbine engine ignitor for startup and cold engine operation.
Let’s go there for a minute. An add on HEI for startup, that supplements current aviation ign systems may be the most simple way to use this fuel. Using paint stripper as fuel (which clearly requires tank/fuel system alterations) or less octane capable fuel is asking for trouble.
What’s interesting about the GAMI fuel is that it works quite well inside the engine, but with SOME aircraft there have been issues with o-rings, fuel lube, paint staining, fuel tanks leaking, and paint damage. There are many aircraft where there has been no negative experience even after years of use. However, it’s not clear yet how an operator can predict whether their aircraft will have issues or not and, of course, that’s what has most Pilots spooked. Either GAMI, or the FAA, needs a fool proof way for an aircraft owner to understand what they need to do to ensure with confidence that they can operate any of the unleaded fuels without fear of damage (or worse).
For those of us who’ve used unleaded fuels, there are a lot of benefits to look forward to, including longer times between oil changes, lower wear and likely higher TBOs eventually, and one less reason for communities to push for shutting down an airport.
I’m glad the FAA is doing the head-to-head assessment so they can help all pilots to know what they’re getting and to have confidence when they make the eventual transition to unleaded fuel, including knowing what changes they may need to make, if any, to ensure their aircraft can safely utilize any of the unleaded fuels entering the market.
Aromatic amines. That’s what you need to focus on. That is what two of the manufacturers are using in order to boost the octane in their fuels and prevent detonation. Aromatic amines are powerful solvents, and are what is responsible for the eating of paint and destroying of seals and bladders in airplanes.
Only one of the three manufacturers (Swift Fuels) has a solution that uses oxygenates other than aromatic amines, whose fuel does not act as a paint remover, and that has zero effect on seals and fuel bladders. I’m not sure why this is not being reported on, instead everyone is focusing on the failures of G100UL.
However….what NOBODY is talking about is compatibility with epoxy resins. There are a LARGE number (many hundreds if not thousands) of aircraft, primarily experimental aircraft, whose fuel tanks are constructed of fiberglass and resin. This is impermeable to 100LL, proven over decades.
To my knowledge, there has been ZERO testing of these new fuels against legacy epoxy resins. Some of these aircraft are built using resins produced by companies that ceased to exist decades ago. There is no way to obtain new samples of the resins for testing, other than cutting test cards out of aircraft. Some second and third owners of experimental composite aircraft have NO IDEA which epoxy resin was used to build their aircraft.
This is a huge deal, and someone needs to report on it.
This statement is incorrect: “Only one of the three manufacturers (Swift Fuels) has a solution that uses oxygenates other than aromatic amines, whose fuel does not act as a paint remover, and that has zero effect on seals and fuel bladders.”
LyondellBasell/VP Aviation’s unleaded fuel (UL100E) is also based on ETBE and does not contain aromatic amines or negatively impact materials. This IS being reported and discussed on FlyEagle.org.
Composites are also being tested by the OEMs, 17 composite resins and 21 composites will be soon tested by the FAA. Cirrus has also tested our fuel on their composites and found that it performs like 100LL. They are getting ready to flight test on a SR 22T.
I suggest you follow our progress here: https://flyeagle.org/resources/
Most of the 100LL is burned by those who need 100LL. Most of the recip fleet (by population) does not need 100LL and can use ethanol free Mogas.
So most of the fleet will be subjected to a fuel not needed, likely more expensive than 100LL (certainly more than Mogas), with the potential to risk acft and life due to as yet unknown outcomes of long term impact to fuel system. Some of the fleet will be on their own to figure out the above due to small numbers of unique acft that are highly unlikely to have anyone (FAA or vendor) take that responsibility or liability exposure. When I was offered the “opportunity” to be a test subject my query on who was going to pay for any resulting damage was met with silence, so I didn’t.
My suggestion:
For anyone that objects to a different approach than “all for one and one for all”, either 100LL users will be subsidized by the larger population of “grass roots” aviation subjected to something potentially harmful they don’t need and costs more, or the portion of the fleet with the deepest pockets will need to absorb more of the risk/cost.
Guess it depends on what you think a democracy is about…population or $$.
The real issue is not the fuel. It is transparency.
We have claims, counterclaims, and hangar talk, but not enough hard, public data. An owner should not have to gamble paint, seals, bladders, or tanks just to learn what is real.
Before I pump the first gallon, I want two answers: what it does in the engine, and what it does to the airplane.
If the FAA is going to drive a nationwide transition, it needs to run the tests in the open, publish the numbers, and spell out the limits and materials compatibility in plain language.
When the FAA looks at real aircraft for reported fuel effects, it needs to publish a dated conclusion and plain guidance. Say what you saw. Say what it means. Say what owners should watch for.
Without that, pilots and owners are being pushed into a nationwide change on guesses, and the costs land on them.
“If the FAA is going to drive a nationwide transition, it needs to run the tests in the open, publish the numbers, and spell out the limits and materials compatibility in plain language.”
I just hope they actually do this, this time. The biggest problem with PAFI/EAGLE is that it was by design a closed-door contest. They wanted to create their own rules after others had already started working on the problem on their own, but I think ultimately that decision set this whole process back several years.
Fuel system materials are being tested by EAGLE. You can look at the specific materials under test, along with the testing protocol and the status of the testing at flyeagle.org. Go to -> Resources -> Piston Aviation Fuels Initiative (PAFI) Process & Metrics -> Metrics -> Materials Compatibility.
Take a look… you’ll likely be impressed by the transparency and methodology of what they are doing.