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Unleaded Avgas Update

Clostermann

Member
Some of you you may be wondering what's going on in this arena. I'll give you my two cents from the inside looking out. So you all heard the noise coming out of Oshkosh about a new UL100 fuel that was supposed to be the answer to everyone's wishes. Everyone got very excited including the pilots associations. Well, Lucy may have pulled the football away from Charlie yet again.

Here's the deal. FAA came out in November saying that the STC route will not lead to "fleet wide approval" of any fuel. What does that mean and why should you care? Well, even though the vast majority of aircraft don't need 100 octane fuel, the vast majority of the fuel consumed is by aircraft that require it. So you know where you are on the totem pole.

This new fuel is unlikely to get "fleet wide approval" from the FAA, unless and until it meets an "industry standard" meaning, until the OEMs and FAA confirm that it is suitable for fleet-wide use and it conforms to an industry standard such as an ASTM fuel specification. Problem is they haven't and likely won't, for three main reasons: 1) the owner won't let them look at it 2) the fuel would not likely pass muster, and 3) the owner has so far refused to go through the ASTM standardization process.

Why not? For several reason including:

1) It may not have have enough detonation resistance to meet the most demanding requirements pf the fleet.
2) its density is higher than 100LL
3) its cost is higher than 100LL
4) the owner has so far refused to submit the fuel for additional testing.

So where does that leave us? The Santa Clara county has announced a ban of leaded fuel starting January 1 2022, likely in the hope they can close their airports and develop the land more profitably. UL94 may work for a while if they don't have any significant traffic from turbocharged aircraft. But make no mistake; this is likely less about public health than real estate development.

The only solution is to develop an unleaded AVGAS that works for the entire fleet. Difficult? yes. Impossible, no. Today we took an important step in that direction with an unleaded fuel that meets detonation resistance in the most demanding engine in the fleet, not a turbo-normalized or inter-cooled engine, and under the most demanding POH conditions.

But it is just a step. There is a lot more testing to go. This is what is required for "fleet wide" approval and for nationwide deployment. The rest is Kabuki theater. Fortunately, your associations finally understand this.
 
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Good info as always. I am slightly surprised that GAMI won't submit to the full process but I mentioned the specific gravity aspect a couple years ago now being a big deal that can only be got around using STCs which is what Swift and GAMI did. Not surprised at the FAA's stance.

Since GAMI was approved for the R2800 under their STC, apparently at 100LL MAP limits, it seems that it would be capable of meeting the detonation margins for GA turbo engines which run less manifold pressure and have similar specific outputs and similar BMEPs.

Can I assume you are talking about a big petroleum company based in Texas here when you say "we"? Seems that if your fuel is approved for drop in, GAMI and Swift fuels will take a big hit in the market unless much cheaper and they install their own tanks at airports.
 
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Since GAMI was approved for the R2800 under their STC, apparently at 100LL MAP limits, it seems that it would be capable of meeting the detonation margins for GA turbo engines which run less manifold pressure and have similar specific outputs and similar BMEPs.

That in itself is surprising since the highest MAP I have heard him quote was tested on his fuel was 42" in the inter-cooled TSIO-550-K. The 2800 runs at much higher MAPs (>50 inches). Makes you wonder what data the ACO relied on to add this engine to the AML-STC....Yet another example of the apparent lack of consistency between STC and PAFI testing.
 
There are factors other than manifold pressure that affect detonation and fuel octane rating requirements of an engine. The Continental has a compression ratio of 7.5, the R2800 is ~6.7 (depending on which version). Cylinder size, intake air temp, cylinder temp all will have an effect. I'm sure there's more too.
 
It would be interesting to study how the military on both sides dealt with varying octane in aircraft during WWII. Octane ranged from 87 for the Germans to 150 for the allies.
 
It would be interesting to study how the military on both sides dealt with varying octane in aircraft during WWII. Octane ranged from 87 for the Germans to 150 for the allies.

Well, mostly they replaced a lot of engines.
 
That in itself is surprising since the highest MAP I have heard him quote was tested on his fuel was 42" in the inter-cooled TSIO-550-K. The 2800 runs at much higher MAPs (>50 inches). Makes you wonder what data the ACO relied on to add this engine to the AML-STC....Yet another example of the apparent lack of consistency between STC and PAFI testing.

This wasn't GAMI but Swift: https://www.purdue.edu/newsroom/research_park_foundation/2011/111025SwiftRadial.html The main point- "Test results showed that 100SF produced a higher detonation onset threshold than 100LL. The engine was operated at 115-145 octane takeoff power settings and there were no indications of engine knock." This was a decade ago.

Seems the R2800s are being limited to around 52-54 inches on 100LL. Similarly on R3350s. I knew a pilot/ engineer on the Martin Mars water bombers in BC.

I suspect there is more testing going on than what is common knowledge. Purdue in particular has strong links to industry and some of the fuel companies going back to before WW2.
 
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It would be interesting to study how the military on both sides dealt with varying octane in aircraft during WWII. Octane ranged from 87 for the Germans to 150 for the allies.

You should read Callum Douglas' "The Secret Horsepower Race-Western Front Fighter Engine Development". There was much more than just the fuel octane ratings going on. Design philosophy, materials, politics...

https://www.amazon.com/Secret-Horse...s&sprefix=the+secret+ho,stripbooks,136&sr=1-1
 
Good info as always. I am slightly surprised that GAMI won't submit to the full process but I mentioned the specific gravity aspect a couple years ago now being a big deal that can only be got around using STCs which is what Swift and GAMI did. Not surprised at the FAA's stance.

I recall that George Braly stated years ago that the problem with the ASTM spec for 100LL was that GAMI’s own testing showed that existing supply of 100LL does not meet the ASTM spec. and that the FAA needs to change it because it is unfair to require unleaded fuels to meet requirements that existing leaded fuels apparently don’t meet.

Skylor
 
Short life span.

It would be interesting to study how the military on both sides dealt with varying octane in aircraft during WWII. Octane ranged from 87 for the Germans to 150 for the allies.

The average life span was only 150 hours before they were shot down. :eek:
 
It's pretty easy to obtain higher octane than 100LL exhibits by using aromatics however the specific gravity of these is generally around 17% higher than gasoline so if you put much in, fuel weight increases which will put you outside the spec. You need to find some other compound to spike octane rating without the extra weight.

Aromatics have known health impacts as well so you are trading the effects of TEL for other potential harms. If they just want to ban TEL, fine, but why trade X damage for Y damage, using aromatics?
 
Ethanol

Just ad ethanol and you will incease resistance to knock.
I have run a standard IO-360, 180 hp for more than 10 years on 5% ethanol.
All fuel lines, mechanical pump is insulated/ vented.
Fuel servo is mounted about 10" from oil pan.
Engine is clean inside, you can still see the criss cross marks in the cylinders.
Mogas has 5 % ethanol here in Sweden and it woks fine.
Only thing I have noticed, on hot summer days >80F climbing to 10,000 ft
one will se reduced fuel pressure for the first 30 min of the flight.
I think that fuel standards may be different depending where you live.
Reducing fuel temperature also works to reduce risk for engine knocking.
 
Vapor pressure

Different countries and states in the US have different, even seasonal vapor pressures for emission control vs. ease of starting in cold weather or due to high elevations or both.

I hope an AVGAS fix of zero ethanol MOGAS will have not only acceptable octane and density but also a standard, very acceptable vapor pressure to keep vapor lock equal or near enough to 100LL.

I'd be fine with a few points denser, once octane is enough to operate without detonation or preignition margins being compromised. It also must flow properly- not vapor lock.
 
I think it's safe to say that vapor pressure of any drop in avgas replacement fuel will be an important spec to meet along with all the others. With STCs, which already exist for using mogas in certain aircraft, some fuel system changes or warnings may be required to comply, due to vapor pressure differences.
 
Pure Ethanol has a higher octane number than gasoline (100 Octane)
Ethanol is an effective octane booster and engine cleaner, available and currently the accepted standard to achieve octane levels for motor gasoline.
According to General Aviation News, 91 octane E10 Mogas has 3%-5% more BTUs/gallon than 100LL.
I'd be fine with a few points denser, once octane is enough to operate without detonation or preignition margins being compromised. It also must flow properly- not vapor lock.
You can boost Octane levels to over 100 with ethanol and detonation is not a concern.( Preignition is not octane related)
Vapor lock can be eliminated by properly designing a fuel system.

Lead (TEL) is the accepted devil to boost 100LL to its required octane rating.
Its toxicity is now widely exploited by overzealous environmentalists and it is high time we accept something in its place.
Especially all of us in the experimental category who have the privilege of experimenting ought to be a little more adventurous with our freedoms
 
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E10 Mogas won't meet the vapor pressure or detonation resistance criteria of current 100LL ASTM specs as a drop in 100LL replacement, though it's been proven to work fine on Experimental installations with proper fuel system design and careful attention to ignition timing, IAT and CHT limits.
 
I agree

E10 Mogas won't meet the vapor pressure or detonation resistance criteria of current 100LL ASTM specs as a drop in 100LL replacement

I am not proposing a "drop in" replacement, just a solution for most of us who operate 8:5 to 1 Lycs. You really don't need 100 octane to operate that engine.
 
My 2 cents, I don't think ANY fuel is going to meet ALL the specs for true drop-in replacement. If they keep waiting for the magic wand, we're all just going to keep waiting. There are simply too many different hooks in the spec, seeing as how the spec was written specifically for 100LL.

I fully expect a variety of fuels and STC's to cover different models, but I think I'll be comfortably dead and buried before a fully compliant drop-in replacement comes about.

Meanwhile I'll keeping running my 91E10 and smile about it. I'm sorry that some folks can't, but I am not able to solve all problems.
 
I am not proposing a "drop in" replacement, just a solution for most of us who operate 8:5 to 1 Lycs. You really don't need 100 octane to operate that engine.

As Greg says, you can use mogas right now as he and others are, being aware of certain limitations and cautions.

This thread was really about unleaded avgas replacements though.
 
MoGas 93 Oct

As Greg says, you can use mogas right now as he and others are, being aware of certain limitations and cautions.

This thread was really about unleaded avgas replacements though.

I am running 100% 93 Oct E10 Mogas in my IO-360 8.5:1 compression engine. The trick to defeat vapor lock is to have the fuel pressurized from the tank to the engine pump. Even 5PSI from a Fauset low pressure pump can do this from the wing root. I'm in Florida, and have yet to see any detonation issues on very hot days.
 
I am running 100% 93 Oct E10 Mogas in my IO-360 8.5:1 compression engine. The trick to defeat vapor lock is to have the fuel pressurized from the tank to the engine pump. Even 5PSI from a Fauset low pressure pump can do this from the wing root. I'm in Florida, and have yet to see any detonation issues on very hot days.

Yes, I know many folks running Mogas with no issues and I run it in my turbocharged Subaru with 9.25 CR plus boost. It still doesn't provide the margins required to satisfy forced induction legacy aero engines though which was what this discussion is about- a drop in fuel to replace 100LL for all piston engined aircraft in use today.

Most RVs can safely use Mogas, no question as so many folks are doing it and have done it for a while. It just doesn't currently have the widespread airport availability to easily plan long cross country trips using it exclusively.

For the RV community, even if 100LL disappeared next year, we'd have some options with Swift, GAMI or Mogas.
 
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Yes, I know many folks running Mogas with no issues and I run it in my turbocharged Subaru with 9.25 CR plus boost. It still doesn't provide the margins required to satisfy forced induction legacy aero engines though which was what this discussion is about- a drop in fuel to replace 100LL for all piston engined aircraft in use today.

And there's the rub - those folks running hotter engines "want" a drop-in replacement that they don't have to think about - just pump it and fly it. That may not be happening, sooner or ever. They may actually have to engage brain and modify their procedures (and possibly engines) to learn how to run a new fuel if they want to get away from lead.
 
And there's the rub - those folks running hotter engines "want" a drop-in replacement that they don't have to think about - just pump it and fly it. That may not be happening, sooner or ever. They may actually have to engage brain and modify their procedures (and possibly engines) to learn how to run a new fuel if they want to get away from lead.

Speaking for myself, I'm willing to engage my A&P to make whatever engine changes are necessary to run the fuel that they pump at my home airport, but it's going to have to be the entire infrastructure. They need to have that fuel at all the other airports I travel to as well. I don't want to have to plan my trips around the availability of the gas that my engine is set up to use.
 
Speaking for myself, I'm willing to engage my A&P to make whatever engine changes are necessary to run the fuel that they pump at my home airport, but it's going to have to be the entire infrastructure. They need to have that fuel at all the other airports I travel to as well. I don't want to have to plan my trips around the availability of the gas that my engine is set up to use.

I don't plan mine around that fuel - I adjust to whatever is local. Granted I have extended range tanks, so I can make better than 1000nm without fuel if needed and frequently tanker my fuel in so I don't have to buy for the return trip - but I'm doing it mostly for price, not fuel quality. 91E10 is about $2/gal cheaper than 100LL. When I make a long trip and need fuel, I buy 100LL just like the rest of us.

If your engine is set up to burn 100LL, you'll always be able to burn 100LL. If you set it up to ALSO be able to burn a lower quality fuel like 91E10 or 93E10, it will happily burn that new fuel OR 100LL, or any mix between. You may need to modify your engine operations when burning just the lower quality fuel (I don't, but others might, test your setup yourself) but it will always be happy to burn a higher quality fuel.
 
It's pretty easy to obtain higher octane than 100LL exhibits by using aromatics however the specific gravity of these is generally around 17% higher than gasoline so if you put much in, fuel weight increases which will put you outside the spec. You need to find some other compound to spike octane rating without the extra weight.

Ross, you are getting warmer... There are other octane boosters that have densities closer to 100LL. They have been used in mogas for decades and have been evaluated by the FAA and others.

https://www.tc.faa.gov/its/worldpac/techrpt/ar06-27.pdf
https://www.tc.faa.gov/its/worldpac/techrpt/ct93-65.pdf
https://www.tc.faa.gov/its/worldpac/techrpt/ar96-42.pdf
https://www.hjelmco.com/pages.asp?r_id=14663
https://www.baylor.edu/mediacommunications/news.php?action=story&story=1141

The key is to use them in the correct amounts to avoid over-leaning and increasing fuel flow, especially in turbocharged engines.
 
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I think it's safe to say that vapor pressure of any drop in avgas replacement fuel will be an important spec to meet along with all the others. With STCs, which already exist for using mogas in certain aircraft, some fuel system changes or warnings may be required to comply, due to vapor pressure differences.

RVP is an important spec, especially on the high end to prevent vapor lock. Not so much on the low end. Some OEMS would like to see the D910 RVP spec tightened to avoid vapor lock.
 
This wasn't GAMI but Swift: https://www.purdue.edu/newsroom/research_park_foundation/2011/111025SwiftRadial.html The main point- "Test results showed that 100SF produced a higher detonation onset threshold than 100LL. The engine was operated at 115-145 octane takeoff power settings and there were no indications of engine knock." This was a decade ago.

Seems the R2800s are being limited to around 52-54 inches on 100LL. Similarly on R3350s. I knew a pilot/ engineer on the Martin Mars water bombers in BC.

I suspect there is more testing going on than what is common knowledge. Purdue in particular has strong links to industry and some of the fuel companies going back to before WW2.

Thanks for the correction. I would have been surprised if the Wichita ACO had included the R2800 in the STC for non-turbocharged engines. This makes more sense. However, the Swift 100SF fuel is a long shot to be commercialized, for reasons I don't want to get into here.

Purdue NaTef is indeed a great research institution especially for materials compatibility. Not sure how much engine testing they are doing these days.
 
I recall that George Braly stated years ago that the problem with the ASTM spec for 100LL was that GAMI’s own testing showed that existing supply of 100LL does not meet the ASTM spec. and that the FAA needs to change it because it is unfair to require unleaded fuels to meet requirements that existing leaded fuels apparently don’t meet.

Skylor

There are indeed many issues with the D910 spec, not the least of which is that a minimum MON of 99.6 is way too low for many engines. This was demonstrated by Cesar Gonzalez of Cessna who presented his findings at the ASTM only to be rebuffed. This is a spec that was developed decades ago, has many flaws, but is still regarded as gospel by some.

I would argue that the FAA is the least of or worries in developing a new unleaded fuel. The ASTM body may be the bigger hurdle.
 
Purdue NaTef is indeed a great research institution especially for materials compatibility. Not sure how much engine testing they are doing these days.

Correct. Not so much aero engine testing as in the past for sure. Purdue refocused facilities towards gas turbine and rocket engine testing circa 2015. Their remaining piston engine test facilities are geared more towards automotive applications these days.

As always, I appreciate your insights on this topic. Good stuff!
 
FAA came out in November saying that the STC route will not lead to "fleet wide approval" of any fuel.
The quotation marks are very important to explain. At that November 15th meeting, the FAA’s Earl Lawrence made it quite clear that the FAA is reserving “fleet wide approval” as a term of art for PAFI-approved fuels. Other fuels approved by STC, from GAMI and Swift Fuels, may be approved for every airframe and every engine in the fleet, and in the normal sense have fleet wide approval. But they won’t have “fleet wide approval” since their approval didn’t come via the PAFI program. I’m not sure any pilot or aircraft owner will care, as long as the fuel is approved, and works… and the FAA says the fuels will work, or they wouldn’t approve them.

the vast majority of aircraft don't need 100 octane fuel, the vast majority of the fuel consumed is by aircraft that require it. So you know where you are on the totem pole.
Not sure what totem pole that is! If all four fuels get FAA approved, whether via PAFI or via STC, that means that the FAA says they’ll work, and I believe they will.

they haven't and likely won't, for three main reasons:
1) the owner won't let them look at it
Actually, Lycoming, Continental, and GAMA have all visited the two STC candidates.

2) the fuel would not likely pass muster
An odd assertion to make… the FAA has approved Swift and GAMI fuels, it hasn’t approved PAFI fuels… maybe it’s the PAFI fuels that are not likely to pass muster?

3) the owner has so far refused to go through the ASTM standardization process.
Is there really an ASTM standardization process? I don’t think that’s what they call it… FWIW, Swift has an ASTM standard, and is committed to the same for their 100R fuel. But there’s no intrinsic value from ASTM that can’t be achieved otherwise, and both federal law and the FAA accept that.

[Why won’t the applicants submit their specifications to ASTM?]
1) It may not have enough detonation resistance to meet the most demanding requirements of the fleet.
The FAA says that both fuels do have adequate detonation resistance. Perhaps you should tell us why you think that the FAA is wrong. But of course, the fuel properties are independent of any specification that the fuel may, or may not, meet.

2) its density is higher than 100LL
Why would that prevent an ASTM spec?

3) its cost is higher than 100LL
The ASTM specification concerns itself with fuel cost? How does THAT work, in your opinion? What is the fuel cost specification for 100LL, in your opinion?

4) the owner has so far refused to submit the fuel for additional testing.
By whom? The applicants have met the FAA’s requirements… specifically, PAFI has refused to recognize the over-a-decade of certification work already accomplished by each applicant. Why would the applicants rationally sign-up to repeat all that work? And why would additional testing affect whether or not a specification is formulated?

This is what is required for "fleet wide" approval and for nationwide deployment.
Fortunately, most of us will be just as pleased with fleet wide approval without the quotation marks, as equally performant and equally FAA-approved. :)

I have a question about the Pierre Clostermann thing… I see you using the photo and name of the French fighter pilot who died in 2006.

Paul Millner
 
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Yes, for RV folks, most won't care whether the fuel is a "drop in" replacement for 100LL as long as the FAA gives it their blessing through STCs or otherwise for their engines and it's widely available at airports.

The frustration of at least 2 of the applicants working under the FAA/PAFI program has been there for all to see for years now. Will have to wait and see how this all pans out in the end with multiple companies competing for market share.
 
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I have a question about the Pierre Clostermann thing… I see you using the photo and name of the French fighter pilot who died in 2006.

A very astute observation, Paul! Since Clostermann died in 2006, no-one can reasonably believe that I am the real Pierre Clostermann or accuse me of stealing his valor. It's just an homage to a great pilot.

Now if I were pretending to be a fuel expert, the imposter charge might stick...;-)

I'll answer your other questions in due time.
 
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Does anyone know if Shell is still pursuing UL Avgas? Not much info from them after 2013.

How about Lyondell? They filed a patent circa 2019 if I recall.
 
Who are you? who is we?

Closterman, can you please identify yourself and your credentials for the information you are posting?
 
GAMA Statement on FAA Approval of GAMI Unleaded Avgas STCs

Today, GAMA announced FAA STC approval.

See the press release here.
 
Pardon my ignorance

Please pardon my ignorance, perhaps I’ve missed something in the prolific amount of information on this subject that has been generated , but if it’s gonna become the only option to be had in the new lead free aircraft fuel world then why and how can it be required to PURCHASE the STC if the new fuel is apparently approved for ALL piston engines. Being compelled to buy basically permission to utilize what’s destined to become the only option just rubs me the the wrong way. Or am I the only one who sees the STC requirement this way?
 
Please pardon my ignorance, perhaps I’ve missed something in the prolific amount of information on this subject that has been generated , but if it’s gonna become the only option to be had in the new lead free aircraft fuel world then why and how can it be required to PURCHASE the STC if the new fuel is apparently approved for ALL piston engines. Being compelled to buy basically permission to utilize what’s destined to become the only option just rubs me the the wrong way. Or am I the only one who sees the STC requirement this way?

You're flying experimental. You don't need an STC.

- mark
 
This is huge. Really should start a new thread for this news.

I’m trying to visualize how the acceptance and transition to this fuel will occur. No STC purchase necessary for experimental but for the rest of the piston GA fleet, not every owner will want to jump right in and purchase the STC, certainly won’t occur in any remotely simultaneous fashion anyway. Further, smaller airports may only have one storage tank for 100L. So how does the switch occur? There will be those with the STC, and those without, and most airports aren’t going to be in any hurry to spend the money to install additional tanks.
 
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This is huge. Really should start a new thread for this news.

I’m trying to visualize how the acceptance and transition to this fuel will occur. No STC purchase necessary for experimental but for the rest of the piston GA fleet, not every owner will want to jump right in and purchase the STC, and smaller airports may only have one storage tank for 100LL, so how does the switch occur? Most airports aren’t going to be in any hurry to spend the money to install additional tanks.

Well, in Santa Clara County, CA, the airports have just one tank, and it will presumably have the 100UL in it. (right now it has 94UL - no 100LL available) So, if you want to buy gas at that airport, you will want to have the STC (or be experimental). I think this will be the typical mode of transition - when the supply is adequate, airports will just start buying it and offering it for sale.
 
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I think this will be the typical mode of transition - when the supply is adequate, airports will just start buying it and offering it for sale.

So the airport will at some point just make the switch and every non-experimental piston engine plane without the STC will just be out of luck until they purchase the STC? I guess that’s the only way.
 
So the airport will at some point just make the switch and every non-experimental piston engine plane without the STC will just be out of luck until they purchase the STC? I guess that’s the only way.

My guess is that owner-operators who haven't bought the STC will just use whatever avgas is available when they refuel anyway, and nobody will really care very much.

"I must insist that you keep burning leaded fuel because you haven't paid a paperwork fee, even though unleaded fuel is available," is probably not a hill the FAA is going to die on.


- mark
 
I posted on beechtalk, what’s an STC? 😉

Cheers HR

‘Supplemental Type Certificate’. If you have a 172, it has a type certificate - a lot of specifications, tests it passed, etc. That type certificate says, ‘must be operated on 100LL or 100/130 av gas meeting astm standard….’ So if your A&P/IA finds any other gas in your plane at annual, he can’t sign it off because it doesn’t conform to its type certificate. An STC is a license to use someone’s data (sort of like a software license) which the faa has blessed to modify the original type certificate, in this case, to use this new gas. EAB aircraft don’t have type certificates, so the notion of an STC for one is meaningless.
 
My guess is that owner-operators who haven't bought the STC will just use whatever avgas is available when they refuel anyway, and nobody will really care very much.

"I must insist that you keep burning leaded fuel because you haven't paid a paperwork fee, even though unleaded fuel is available," is probably not a hill the FAA is going to die on.


- mark

There is a possible wrinkle here - the STC may not simply be a paperwork fee. I know that the SWIFT 100UL has a higher density than 100LL. (about 4%)
I'm not sure about the GAMI 100UL, but I think it may also be heavier. It also has slightly higher energy content per gallon.
So - presumably the STC for a particular airplane would include revisions to appropriate sections of the POH to revise range and payload and W&B data? Or, it would have to contain some kind of language that says the difference has been deemed insignificant so carry on with the old POH? Anyway there may be more to it than simply a 'license' to use it. now at this point, I can't imagine how GAMI or anyone else could have developed revisions to all the POHs of all the certified piston-powered GA aircraft, so????? How is that going to work?

A separate point: When you pay for an STC, you are helping to amortize the development cost that was invested. What GAMI has finally done is a really good thing, and they deserve to make some money off of it. Presumably some kind of royalty or license fee from the refiners, and STC fees. We shouldn't begrudge them that, as long as it is 'reasonable'.
 
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