You may have heard the story about a young student who took a math test. One of the questions was a word problem about a farmer who had two chickens. The two chickens only produced one or two eggs a day and he wanted to have two eggs for breakfast every day. His solution was to buy two more chickens so that he would have at least two eggs every morning. How many chickens does the farmer now have?
The student was quick to analyze the situation and answered four.
The next day the student was upset when the teacher marked the answer wrong. The explanation was that the student should have used new math and that the correct answer was 5.89 chickens.
This story reminds me of the 100 octane saga going on in general aviation for the last 25 or 30 years, when the need for an unleaded fuel to replace 100LL was first recognized.
There were a lot of meetings at ASTM (American Society for Testing and Materials) and elsewhere, but not much happened for a while.
Then Swift Fuels announced it had an unleaded 100-octane fuel, which was basically ETBE (Ethyl Tertiary Butyl Ether). But the energy level of the fuel was quite low. That, combined with some other problems, led to the failure of that project, with Swift Fuels going back to the drawing board.
The FAA and others then formed the Piston Aviation Fuels Initiative (PAFI), an interindustry task force to develop a 100 octane unleaded avgas. There were a number of candidate fuels that were tested, with experts weeding them out until there was only one left. That included a candidate unleaded fuel from Shell that disappeared after further testing.
There was a lot of despair at this time with debate between the FAA and the EPA over who was in charge. The FAA sort of won saying that this was a safety issue and that they needed to handle it.
Somewhere in the midst of all of this, the people behind a company called GAMI — General Aviation Modifications Inc. — got to work on the problem. Their first step was to build a very sophisticated engine test cell to help them study the problem and evaluate different candidates.
I visited them years ago and was very impressed with their test set up. It was far above anything like it elsewhere.
Their work paid off and several years ago they started the certification process for their fuel, known as G100UL. A few years ago they got approval for flight tests with a Supplemental Type Certificate (STC) in certain models, then in 2021 the fuel was approved for a limited number of engines, including Lycoming O-320, O-360, and IO-360 piston engines.
I was at EAA AirVenture Oshkosh 2021 when this was announced. Everyone who heard about it was euphoric and relieved that there was a good answer to the unleaded question and that GA would live another day. This was comparable to the four chickens answer.
That success was followed in September 2022 when the FAA expanded GAMI’s STC to the entire general aviation fleet. The STC covers “every spark ignition piston engine and every airframe using a spark ignition piston engine in the FAA’s Type Certificate database,” essentially creating a drop-in replacement fuel for general aviation.
Several months before the milestone approval for GAMI’s fuel, a group of industry organizations formed another initiative, known as EAGLE — Eliminate Aviation Gasoline Lead Emissions — to solve the 100LL replacement issue by 2030.
The EAGLE efforts were recognized in late 2022, when President Joe Biden signed legislation that included $10 million to support the qualification of a suitable fuel or fuels.
So far, the FAA has identified four candidates: The GAMI fuel, a Swift fuel, a fuel from Afton Chemical/Phillips 66, and a fuel from Lyondellbassell/ VP Racing.
The GAMI fuel is a blend of high octane alkylate and other high octane hydrocarbons. The Swift fuel is supposedly a blend of alkylate plus ETBE and possibly ferrocene, an iron compound. The other two candidates are rumored to be based on alkylate plus MMT, a manganese compound.
When I first started at Shell, I liked to read old reports on work that had been done. Several of the reports were on work to find an alternative to tetraethyllead (TEL), the lead fuel additive that is a patented octane rating booster and helps prevent knocking in piston aircraft engines.
It seems that most every metal in the right compound worked as an antiknock in spark ignition engines. But research found that lead worked well and the bad side effects could be controlled somewhat.
Iron compounds tended to increase wear and foul spark plugs very quickly. MMT, the manganese compound, also fouled spark plugs with a very nice looking, but harmful, reddish deposit.
So now I come back to the story at the top of the column. The FAA and EAGLE must decide who to back and promote as the future of GA. The GAMI fuel has a proven record and works well in all tests to date. The Swift fuel has less energy and may contain a spark plug fouling agent, while the other two also may contain spark plug fouling agents that leave pretty deposits.
What a tough decision. Which fuel — or fuels — do you think they will support?
Some clarification. It is unfortunate that some of these facts have not been made crystal clear by the other publications and alphabet groups. They have each been rather thoroughly briefed on each of these issues.
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1) GAMI has no intention of being a “sole source” producer of G100UL avgas.
2) The FAA quality assurance manual for the approval of the production of G100UL avgas includes a provision and a corresponding standard (boilerplate) License document.
3) Our explicit representation to the FAA – – which is part of the FAA approved certification package – – is that any qualified blender or refiner that wants to produce G100UL Avgas will be able to obtain a license on exactly the same non-discriminatory terms and conditions of any other.
4) As a result, there can be no “monopoly” with respect to production, other than one that might naturally occur as a result of one blender/refiner being able to produce a conforming G100UL avgas at a consistently lower delivered price than all of the others. But that is no different that the current situation with 100LL avgas.
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Regards,
George Braly
Head of Engineering
GAMI
Money, money money, that’s what it’s all about, once someone figures out how to bottle this stuff and no one asks why the price is so expensive, then it will be marketed without further comment, that’s all it is, there are just to many people still asking why the price is so high, because this is a very lucrative product and it will make a lot of people very rich. If no one ask why the price is so high, it would of been on the market years ago. The biggest problem is justifying the high price they want to charge for this stuff. Once its accepted for the high price, there will be absolutely no problem of any sort. That is the absolute problem, money, money money. Everything will fall into place smoothly, guaranteed !!
The truth is that GAMI’s fuel just isn’t there. The MON octane (motor octane) ASTM 2699/2700 of their fuel is insufficient in meeting even the recently lowered specs for the high octane requirements of the fleets 30% majority of which are commercial small businesses and serve remote places and are fundamental in preserving those small economic markets. This 30% of the fleet serves in the heartlands of the USA by dusting the crops and providing fertilization over the bread basket of the world! GAMi is conducting a huge marketing campaign to put pressure on the FAA to lower the safety standards below the minimum specification level on the high octane fleet. Gami is gambling with pilot and passenger’s lives to make a buck. The silent team is the one to watch out for in this race I put my money on Lyondellbassell/ VP Racing
The Cirrus fleet is now using tons of 100LL and they actually need it. However, on parent company AVIC’s Continental Engines website, they claim to be the market leader in certified Jet-A piston engines. Is AVIC really not capable of installing their own engines in their own aircraft?? This is a very large percentage of the leaded fuel consumption.
I have an O-320 in a 172. I have the STC for 91+ octane unleaded fuel with no ethanol. It runs great. After hundreds of hours the engine is clean and has high compressions. Plugs need very little cleaning after each 100 hours. It may not work for high compression engines, but I’m having great success. My only problem is my airport fighting it vigorously and wants to force me to buy Avgas from the FBO.
I have thousands of hours of using the e-free unleaded gasoline in my airplanes via the EAA STC. We don’t need leaded or 100 octane fuels. We need a willingness to use engines in our aircraft that use Jet-A, e-free gasoline, and approved 94UL avgas. The GAMA manufacturers need to step up with real changes that are legal and safe. Its not that hard. The Pipistrel Panthera is a good example of this willingness, and the product is now owned by Textron.
One part Bombay Gin, three parts Marvel Mystery Oil; shaken not stirred. Skip the olive. Works like a champ.
How about butanol fuel? Almost as much energy as gasoline without the disadvantages of ethanol
Maybe use propane as a lot of forklifts do? 91k btu per gallon and an ‘octane’ rating of 105- 115, and is a liquid at low pressures, but the tanks are a bit heavy.
Don’t remember all this commotion when cars switched to unleaded.
I you were driving a car in the 70’s you lived through the exhaust valve issues and muscle car engine failures., and the complicated exhaust emission add-on devices that made a car run poorly.
It all started in 1975 and took until 1996 to stop selling leaded gas. So, it was a long transition, selling both types of fuel.
Then there was the MTBE problem in the 80’s with leaking fuel tanks contaminating ground water.
So, we wound up with ethanol, which mixes with water, and corrodes aluminum.
Now we embark on the replacement of 100LL with G100UL, and not too soon for me.!
The use of ‘supposedly’ and ‘rumored’ to describe other fuels comes across as very biased to G100UL fuel, especially since the pre-released version of GAMI’s fuel during the PAFI was ‘rumored’ to ‘supposedly’ strip paint from airplanes if spillage occurred. Let’s support all the unleaded options currently being explored based on facts, not rumors.
GAMI never participated in the PAFI project. It was the Shell fuel that was “rumored” to strip paint.
Thanks for the clarification.
To the extent possible, let the market decide. Yeah, that’ll be problematic, but it’s better than letting the federal government pick a winner. Their track record is poor.
Unfortunately I fear the free market will not get to decide this one
Why do they have to pick just one? Why not two so they don’t create yet another monopoly? And as long as both fuels mixed in a tank do not lead to problems (which needs to be tested even now while 100LL is still in use) this would make things similar to gasoline in automobiles now. You can buy from any gasoline maker and mix it in your bulk tanks with no problems.
Having multiple brands prevents problems when the single source has a major refinery problem like a fire, tornado, earth quake, etc. This problem would surface after the single choice is made and EPA’s outlaw of LL is fully implemented. A lot of non-recreational GA aircraft will be grounded and we’ll be delayed as ground transportation tries to cover the problem.
The FAA will pick whichever company politicians hold a stake in. It’s all about who makes the money
The FAA will pick whichever comapany politicians hold a stake in. It’s all abotu who makes the money
All this money wasted, in that TEL in aviation fuel is inconsequential considering the very, very small percentage of Avgas used in the United States, when measured against the total national consumption of gasoline.
Now, if an STC is required for 100UL use, why wasn’t an STC needed for 100 octane use in those 87 octane drinking engines when 80/87 was phased out in the ’70’s? Anyway, now we wait for engine problems to surface with using this new fuel, just like in the ’70’s when green gas was all one could get!
The very, very small amount of TEL comes to 1 million pounds of leaded emissions every year from GA aircraft. There are some people who think that is far too much since there is no safe level of lead in the blood.
One million pounds of leaded emissions yearly? I have to see proof of that number. The actual content of led compound in aviation fuel is so low that to have a million pounds of the stuff the fuel consumption would be vast, and the number makes no sense.
My rough calc;
333 million gallons used annually , and 2 grams TEL per gallon = 1.48 million pounds of TEL .
But how much of pb lead compound is released in the exhaust after combustion and the TEL combines with the ethylene-dibromide that forms lead bromide, and how much remains in the engine as deposits and dissolved in the oil ?
As a reference, world lead emissions from gasoline in the 1970-1973 range was 170,000 tons per year, or 340 million pounds … !
The Baumann and Heumann emission factor (BHEF) of about 28%, implies about 280,000 pound emitted to the atmosphere from 1 million pounds of pb-br from avgas combustion.
So, with the reduction, from above, over the last 50+ years, what is the net affect now ?
I will use G100UL as soon as it’s available …!!!
So it doesn’t matter to you that children living near general aviation airports that only offer leaded avgas have raised blood lead levels leading to lower IQs and lower lifetime earning capacity? That has been scientifically proven. So you apparently consider the ruined lives of those children as inconsequential? Shame on you. You give aviation a bad name!
There has to be a back story about the FAA and GAMI that is preventing the feds from giving full support to G100UL. From the pilot perspective, it is suspicious and disappointing.
Usually the one that makes the most sense, pick the opposite of that. That is the one the FAA will pick.
DITTO