The FAA didn’t cancel those old 115, 100, and 80 octane fuels; market forces drove the refiners to stop making them (along with the old 91/96).
I do not wish to be argumentative nor do I want to start a dialog that strays too far afield, but I must disagree. GM first tested TEL in fuel December 9, 1921. Between 1922 and 1939, Standard Oil, Du Pont, Ethyl Corp, I.G.Farben, and the US Navy experimented with various recipes utilizing TEL as an additive to support new engine technologies in the face of declining fuel qualities. TEL at the time was considered a “Gift from God” in spite of injuring or killing many workers employed in the acquiring of raw lead materials and the refinement of the product. It’s not like oil companies just stumbled on this. Lead substitutes and additives as a concentrate have been marketed in Europe for the last 100 years and it is still available in some areas here.
At the risk of exposing myself as a complete ass, I might add that the FAA has a Congressional mandate to use consensus standards in AC 23.2010-1, Chapter 5 and FAA Order 8000.376. The mandate is repeated at every reauthorization as a budgetary measure, taking advantage of existing experience and expertise when deemed appropriate.
Well, not to burst your bubble BUT IT SHOULD NOT “take time and many people have to be involved in order to get a safe unleaded AVGAS.” The very fact there are so many “hands” involved in the process is what is making it a nightmare!!! AS for the ASTM, please reference an article in Aviation Consumer High-Octane Unleaded: Where Are We? - Aviation Consumer
It is the best description of the history of the search for a replacement to 100LL. It also provides a good “picture” of the current state of the Avgas fiasco!!! It showcases the infighting, stonewalling, waste of taxpayer money etc between the FAA, the fuel developers, along with the National Air Transport Association (NATA)
It also addresses the unneeded involvement of ASTM.
ASTM International was formerly known as “American Society for Testing and Materials”
Is NOT a FAA or government organization
Is an organization that develops and publishes international technical standards for a wide range of materials, products, systems and services.
Creation of a ASTM Standard Is a long drawn out process
ASTM standards are adopted, by being incorporated into many federal, state, and municipal government regulations
ASTM International has no role in requiring or enforcing compliance with its standards.
ASTM gets PAID by whatever agency that uses the standards they have developed The REAL REASON ASTM wants in on the fuel development!!
Also
An ASTM spec is not a recipe
It creates a spec that must be met! BUT, does not supply “recipe” for meeting the spec. SO, it requires that a series of laboratory tests must be run on every batch of fuel produced. CAN YOU SAY MO’ MONEY SPENT which raises the cost of the product!!!
This results in the “recipe” of a product being different between manufactures. IE** Chevron’s recipe is different than Phillips’ which is different than Exxon’s, etc.
So as you can see requiring an ASTM Standard may not be as desirable as one might think.
You mention ETBE which is also referenced in the article
ETBE (Ethyl-tert butyl ether) is ethanol based, but is classified as an “ether.”
what happens to aircraft engines when mogas with ethanol was used?
The rubber compounds in the fuel systems and engines fell apart.
At Oshkosh this year, data was provided that strongly suggests that the use of ETBE will create problems with diaphragms and other rubber components in our aircraft fuel systems.
Further, California statutes, make ETBE illegal for use in self-propelled vehicles. We didn’t see an exception for aircraft.
SO, how can ETBE be used in California
Currently there are 3 replacements for 100LL BUT, Does anyone really think that having 3 or more 100LL replacements to choose from is a good thing!!!
What about having different airports supplying 3 different kinds of fuel to GA being a good idea??
And, two of those choices CAN NOT BE USED in ALL GA Aircraft
Somehow, the bureaucratic nonsense needs to end. I for one do not think the industry needs to end up with multiple inferior products replacing 100LL due to bureaucratic ineptness!!!
2 Likes
The truth is there is ONLY ONE true replacement for 100LL It is GAMI’s 100UL which is true drop in replacement! it can be used in ALL GA Engines with NO limitations!!! Unlike the other 2!!!
I agree on the footdragging!!! The FAA should make the best choice and get it to the market with no more delay!!!
So as exciting as the media releases are, the majority of the RHV STC purchases were “because they’re free, and I might need one someday…” And the Swift 100R at KSQL is only legal for 2 versions of 172’s, since FAA is withholding broader STC pending ASTM Spec release. And the GAMI STC kit came with warnings to have absorbent cloth towels available to immediately clean any spillage plus ceramic coating of painted surfaces near the fillers to prevent “damage”… It is good that George found a market at RHV for his inventory of G100UL, but the unleaded Avgas problem hasn’t quite been solved yet. Patience Grasshopper…
I think you are missing quite a bit here. The use of consensus standards is directed in as far as those standards:
- Exist
- Are appropriate and applicable
Standards support the TC and STC process, they do not supplant it. Even when things are built to standards, their design often still needs to be FAA approved - look at just about every single mechanical and electronic component on your aircraft as examples.
The only exceptions where the part doesn’t need to be approved are for standard parts - things like fasteners. Those can be used without approval of the part, but how it is used and where it is used still needs FAA approval.
Where no standard exists (like for 100LL replacement) then the ONLY approval process that exists is via the TC or STC process. Full stop.
Wow ! Best as I can understand having FAA approval is only part of the process of bringing a new aviation product to market.
For many years there was an unleaded car gas called Mogas (Petersen STC) widely available for most 90 octane aircraft engines and that has now disappeared except in Alaska where Premium car gas is 92 octane and ethanol free.
Seems to me that a simple option has been replaced by some very complicated alternatives !!
“Isn’t that what everyone wanted?” The answer to that question, posed in your sub-head, is: NO!
Because those two “competing” fuels are not, according to their respective manufacturers, mixable with one another. They can both be mixed with 100LL in any proportion (good), but not with one another (bad bad).
So, two airports roughly 8 flying minutes apart will be selling fuels that can’t be used in the same tank. Fantastic.
Also, it should be emphasized, G100UL has an STC covering every fixed-wing airframe and spark-ignition engine in the FAA registry, with expansion to rotorcraft coming shortly. Swift has an STC covering two (2) aircraft, neither of which requires 100 octane fuel in the first place, as you noted.
As someone who bases an aircraft at San Carlos that can’t use 94UL and isn’t on the G100 STC, I’m disappointed to say the least.
1 Like
I have seen stated from many sources that 75% of the GA fleet can run on that same mogas, at a price point 1/2 to 1/3 the cost of these new UL fuels, and the benefits of decreased maintenance and increased engine longevity.
If the California legislature is actually concerned about getting the lead out, why haven’t they made an allowance in the “all gas must contain ethanol” decree to allow airports to sell this fuel?
Why is virtually nobody agitating for this extremely easy partial solution affecting a super majority of piston aircraft owners that will have the added benefit of helping increase the GA population through reduced operating costs?
That ratio at my little uncontrolled home airport is probably closer to 90%. There are 2 tanks and a fuel truck with 100LL. They could easily use 1 tank for mogas with no ethanol as sold in Alaska, keeping another tank and the fuel truck for 100LL, were they allowed to purchase and sell it by California law.
And another thing, the mogas is fungible (can safely mix with) with 100LL.
Airports with a single fuel tank can continue to sell only 100L.
Lots of things to unpack here today. Thank you, Russ, you have done an excellent job of keeping us all appraised of both the progress and the lack of progress on this front. Equally valuable, you provide us all with a forum to jump in and set the world straight - even though the majority of us are not fuel chemists either (leaving the door open in case I am the only one who’s STEM education is on par with Russ).
I was not involved in aviation back when 100LL became the “go to” fuel, but my training back at the turn of the millennium made clear what clear, red, green, and blue fuels were, and to pay attention that what went into my tanks was what I expected. Based on this, I would assume that not seeing those fuels at every airport doesn’t mean they were legislated into oblivion, but simply became less economically viable over time. It seems we unilaterally agreed to reduce the lead content at some point (thus the low-lead moniker), but I suspect that this is the first time we are intentionally creating a one-size-fits-all unleaded fuel for GA as a whole.
We have had unleaded aviation fuels for quite some time, but 100LL has dominated ever since I can remember. That would suggest that in spite of spark plug fouling (and being quite toxic) TEL must have some redeeming quality that is difficult if not impossible to find in equal degree elsewhere. To my understanding, the magic is not simply that it prevents detonation at this high of an octane, but that it produces a very smooth and consistent burn front as the flame propagates through the cylinder which is relatively gentle on the engine considering evenly distributed acceleration and evenly distributed heat. Of equal importance, it achieves this with nothing more detrimental to the engine itself than yucky (industry term) lead build up on the spark plugs.
In the search for a replacement fuel, we have three requirements. The first two are simple and straight forward: (1) 100 octane, (2) no lead. The third requirement is a little less clear: “whatever you do to achieve the first two items, it can’t have any side effects that are bad or unexpected”. This includes (1) shouldn’t cost more, (2) don’t degrade or interact with seals, gaskets, hoses and the like, (3) don’t cause parts on my engine to wear, (4) don’t make concentrations of heat in my engine, (5) stay fresh in my tanks and my carb literally forever. And (6) at least 100 more things that I am not smart enough to foresee. We’ve been told that the new fuels are everything we would ever hope for, but we have learned in recent years to be skeptical of the “experts”.
Whatever the “industry” chooses to go with, I will be stuck with. My ship will happily run on low octane, unleaded fuels, but it has only ever had 100LL in its tanks because I fly coast to coast and airfields that offer anything other than 100 low lead are few and far between. When the new and improved wonder gas is officially adopted, it will completely replace 100LL, and it will likely replace the lower octane fuels as well. Call me a nervous Nelly, but I believe in the maxim “The monster you know is better than the monster you don’t know”. As much as I want unleaded fuel, what are we replacing the TEL with, and will that new something turn out to be a monster in it’s own right? Only time will tell, and I am a proponent of taking all the time we have been given.
I don’t believe that EAGLE’s purpose is simply to see one or two unleaded high octane fuels reach the market. The goal should be to shepherd in the best replacement fuel we are capable of developing. Right now, 100LL still dominates across the country, and the amount of alternative fuel sold thus far isn’t even enough to taxi our fleet of GA aircraft to the run-up area. We have a long ways to go.
I believe that ASTM certification is important. It isn’t that the ASTM people are all knowing and will pass judgement on the formulation. The ASTM process allows the industry stakeholders (fuel manufacturers, engine manufacturers, aircraft maintenance shops, owners and pilots) to participate in creating a consensus criteria for the fuel and its manufacture such that any supplier can then be held to a consistent standard for formulation, performance, purity, etc. GAMI will not be the sole manufacturer or supplier of the new fuel for long (assuming it goes that way), and we want to guarantee that every “brand” of Avgas is the same as every other in formulation and performance.
I am happy to see both alternative fuels finally being sold. We need more exposure to these fuels than what we have seen so far. The FAA has approved an STC for GAMI’s fuel which was tested to their satisfaction, but I am unclear on what that entails. AOPA flew a single aircraft with GAMI fuel in one of two engines for a year. A large flight school used unleaded 94 octane for an extended period of time and then opted to return to low lead. Beyond that, I know very little about just how suitable these fuels are in certificated engines, and much less in my non-certificated Jabiru engine. After a million gallons have been consumed (rather than 1,000), we will start hearing about different people’s experiences with less than ideal engines, less than ideal test beds, and less than ideal engine management.
We still have six years; we should use every one of them to continue to assess, tweak, improve and reassess before we get into bed with something that we will have to “like it or lump it” for a very long time after.
Why have a simple solution when complicated alternatives can be developed ?
1 Like
Automotive engine heads were improved, using materials from high performance engines was one way.
Owner of old muscle cars stick to high octane gas, which is available in some jurisdictions such as BC, where Chevron and Co-op sell a 94 octane without ethanol and AFAIK without lead. BC law only requires an average minimum ethanol, so using a bit more in lower grades facilitates not using any in the highest grade.
There are additives of course, and racing fuels.
I don’t know what the Martin Mars was using and will in its last flights, years ago they either flew back to Sproat Lake at night for refuelling and maintenance, or had a road trailer with needed high octane fuel. (As in Fort McMurray AB or the reservoir in south TX from which it fought fire in northern Mexico. With a trailer for maintenance and parts.)
(Hawaii Mars has made its last flight, to a museum at YYJ.
Philippine Mars is in the water under power, being readied to fly to a lake in AZ then transported on land to a museum in Puma AZ. Forecast to depart on November 18.)
With no idea of the age or mileage - or, presumably, how the engines were treated - why did you assume that the lead was a factor in their condition?
Because i had no other theory. The cylinder heads of the unleaded fueling, were clean and pristine inside. Although severely pitted valves, seats, and sunken into the units.
Even though the leaded fueling heads were crudded up pretty badly, upon cleaning and inspection, they were basically in perfect condition and shape.
I didn’t see any evidence of either sets of cylinder heads being out of air / fuel ratios. Neither looked like they were running too lean, nor too rich. So my best guess was that the lead in the fuel prevented any damage.
These issue were solved a LONG L:ONG LONG time ago. I have run Four engines Past 400K miles on regular unleaded. The need for hardened seats was determined in the late 1960s. If there was pitting and valve recession then those engines did not have satellite or equivalent materials for the valve seats.
Actually, 94 octane isn’t high. My father told me that back in the late 60’s-early 70’s, 95 octane was the norm for leaded regular fuel. And the premium leaded fuels were between 100-102 octane.
And when one considers 130 octane aviation fuel, which i don’t think is available anymore, that really puts it into perspective.
When i took those engines apart, it was the early 80’s. So yes, perhaps the engine didn’t have the hardened valves and valve seats.
I recently retired my Pontiac with 263K on the clock. No issues with the engine, and it always had unleaded fuel in it too. I was hoping to hit 300K, but the need was dire for a replacement.