Would we need a STC for unleaded fuel?

[EricJ]

47 minutes ago, GeeBee said:

I think you will find it says, "grade 100" or "100 grade minimum". In that case it has to be a ASTM spec fuel. The word, "grade" makes it so. Same with the term "100LL" or "100VL"

Where is that rule written?    "Grade" is a pretty generic term.

 

[GeeBee]

2 hours ago, EricJ said:

Where is that rule written?    "Grade" is a pretty generic term.

 

It is in AC 20-24D which I previously posted above. In that AC, the FAA outlines the, language, form and content of TCDS(s) and accepts ASTM and SAE language of "grade" and other terms such as "Jet-A". ASTM outlines the specification for "Grade 100 aviation gasoline" in D-910. The AC also says if you use the term such as "grade" to refer to something other than "ASTM" or SAE definitions you must note the entity and propound upon it's specification for that grade.

https://www.astm.org/d0910-21.html

Nor is avgas the only place where the ASTM uses "grade". If you call your local steel supplier and ask for "grade 100 steel" (vs "grade 100 aviation gasoline) you are referring to a steel that meets the ASTM specifications for "grade 100 steel". 

[EricJ]

6 hours ago, GeeBee said:

It is in AC 20-24D which I previously posted above. In that AC, the FAA outlines the, language, form and content of TCDS(s) and accepts ASTM and SAE language of "grade" and other terms such as "Jet-A". ASTM outlines the specification for "Grade 100 aviation gasoline" in D-910. The AC also says if you use the term such as "grade" to refer to something other than "ASTM" or SAE definitions you must note the entity and propound upon it's specification for that grade.

https://www.astm.org/d0910-21.html

Nor is avgas the only place where the ASTM uses "grade". If you call your local steel supplier and ask for "grade 100 steel" (vs "grade 100 aviation gasoline) you are referring to a steel that meets the ASTM specifications for "grade 100 steel". 

Yes, exactly, the use of the term "grade" can mean many different things from different standards, which was essentially my point.  So if a "grade" is specified in a change to a TC or STC or other relevant document, particularly as an operating limitation, the relevant standard defining "grade" in that context should be identified, but it does not have to be ASTM.   The AC even cites the MIL-STD process, including UK mil specs, or even Russian or Chinese standards.   If a term, like "grade", is used in a way that is limiting, the relevant standard, whatever it may be, should be cited.   It could be a Russian or Chinese standard according to AC 20-24D.   This is generally consistent with how standards are applied in industry when multiple different standards may be applied in a particular context.

This is contrary to what you've been stating previously, that ASTM has to be used.   AC 20-24D, which you've been citing, is pretty much spending a lot of time saying that isn't true, that there are lots of standards, including "The FAA will also accept fuels identified by independent specifications...", and that whatever is used should be identified consistent with methods described in the AC.

I think you have been consistently misinterpreting this AC.   It does not say "grade" is an ASTM term, or that ASTM language or standards must be used.   On the contrary, it explains how ASTM is only one of many possible standard sources from which fuel may be described or specified, and that new ones can be created.

[GeeBee]

I think you need to read paragraph 8 (e) on "alternative standards"

If you want to see Jesus in the toast, the toast will deliver that image.

 

[MikeOH]

38 minutes ago, GeeBee said:

I think you need to read paragraph 8 (e) on "alternative standards"

If you want to see Jesus in the toast, the toast will deliver that image.

 

How do I view 8(e) upon which you hang your hat; it appears I need to spend $54 to view it!

Also, please explain where an AC (ADVISORY Circular) is LEGALLY MANDATED.

[EricJ]

1 hour ago, GeeBee said:

I think you need to read paragraph 8 (e) on "alternative standards"

If you want to see Jesus in the toast, the toast will deliver that image.

 

I read it before I posted.

8(e)1, "The FAA has determined that independent fuel specifications may be acceptable for definition of aviation fuel operating limitations if they provide an equivalent level of property, performance, and quality control as governmental, military, or industry voluntary consensus based standards."

That's just par 1.  

BTW, the word "alternative" doesn't appear in AC 20-24D, so perhaps you're reading a different document?
 

 

[MikeOH]

@GeeBee

Consider a context outside the U.S.  Piston planes operate all over the world, many are of U.S. manufacture and certification, and some continue to fly under U.S. registry.  Do you honestly think all of them are operating ONLY on fuel certified to meet the ASTM D-910 standard?

If you are a realist, it is obvious they all do not.  Is it your contention that those that do not are in violation of some law or regulation?  Or, is it more probable they are operating on fuels that meet other standards or specifications (100 grade aviation fuel) of the countries/standards bodies in those locations?

In the case of Braly and his GAMI 100UL do you not think his greater than a decade development efforts have not extensively tested his fuel?  Likely well beyond the requirements of any one of many different aviation fuel standards out there.  To my knowledge this is supposed to be a "drop in" fuel with NO requirements or alterations needed whatsoever to the aircraft.  Consequently I can think of only two reasons he is not simply certifying to a particular standard (ASTM D-910 being one example):

1) He wants to shift at least some liability to the Feds; if he can get them to issue a 'blanket' STC he would have that.

2) He wants to profit from the sale of STCs (Beyond payments for royalties for the use of his 'recipe')

I certainly don't begrudge him making a profit, but I do object to being forced to purchase his STC; we are going to be paying more (likely a lot more at retail) to repeatedly buy his product.  And, if the Feds have their way (EPA/whoever bans leaded avgas), then we will be forced to buy his product regardless.  Therefore, IMO, the FAA issuing a 'blanket' STC to his company is tantamount to giving him a monopoly!!  Not exactly the function of the Feds!  Or, these days, maybe it is  If they ban leaded avgas he'll have a de-facto monopoly anyway!  To be forced to buy an STC as well??? That's simple greed right there.  Not that I hold the Feds in any high regard, but perhaps they actually have the foresight to know this and that is why no 'blanket' STC has been issued.

The above is why I am so vested in the true legal necessity of an STC.  If not legally required, we can thumb our noses at paying for his STC!

[carusoam]

Sounds like one of those interesting topics for the AOPA political/legal team….

Best regards,

-a-

[GeeBee]

10 hours ago, MikeOH said:

@GeeBee

Consider a context outside the U.S.  Piston planes operate all over the world, many are of U.S. manufacture and certification, and some continue to fly under U.S. registry.  Do you honestly think all of them are operating ONLY on fuel certified to meet the ASTM D-910 standard?

If you are a realist, it is obvious they all do not.  Is it your contention that those that do not are in violation of some law or regulation?  Or, is it more probable they are operating on fuels that meet other standards or specifications (100 grade aviation fuel) of the countries/standards bodies in those locations?

In the case of Braly and his GAMI 100UL do you not think his greater than a decade development efforts have not extensively tested his fuel?  Likely well beyond the requirements of any one of many different aviation fuel standards out there.  To my knowledge this is supposed to be a "drop in" fuel with NO requirements or alterations needed whatsoever to the aircraft.  Consequently I can think of only two reasons he is not simply certifying to a particular standard (ASTM D-910 being one example):

1) He wants to shift at least some liability to the Feds; if he can get them to issue a 'blanket' STC he would have that.

2) He wants to profit from the sale of STCs (Beyond payments for royalties for the use of his 'recipe')

I certainly don't begrudge him making a profit, but I do object to being forced to purchase his STC; we are going to be paying more (likely a lot more at retail) to repeatedly buy his product.  And, if the Feds have their way (EPA/whoever bans leaded avgas), then we will be forced to buy his product regardless.  Therefore, IMO, the FAA issuing a 'blanket' STC to his company is tantamount to giving him a monopoly!!  Not exactly the function of the Feds!  Or, these days, maybe it is  If they ban leaded avgas he'll have a de-facto monopoly anyway!  To be forced to buy an STC as well??? That's simple greed right there.  Not that I hold the Feds in any high regard, but perhaps they actually have the foresight to know this and that is why no 'blanket' STC has been issued.

The above is why I am so vested in the true legal necessity of an STC.  If not legally required, we can thumb our noses at paying for his STC!

Regarding what others do in other places of the world is immaterial. Those airplanes are operated under regulations or no regulations that may or may not require adherence to AFM, POH, TCDS specifications. If you look at the IO-550 TCDS they provide 4 specifications for "aviation grade gasoline" that are approved. Continental will tell you their certification basis is the ASTM formulation. They say it over and over. They will tell you that if you operate with a fuel outside of the certification basis, all bets are off. Indeed Continental says it on Page 55 of their "Operating Tips Manual"

If you don't want to buy an STC, go experimental. You are free to do anything within the limitations of that category. Meanwhile with the airplane you got, you've agreed to operate it within certain parameters, rules and regulations. 

As to giving Braly a monopoly. Braly is not stopping anyone from developing another fuel. If someone does the kind of work he has done they can be awarded an STC too. 

De facto monopolies occur every day in this nation. They are called patents.

 

 

[Pinecone]

The bottom line is, if you agree or disagree about "grade" and the ASTM standard, G100UL is BEING CERTIFIED USING THE STC PROCESS.

George is pursuing allowing his fuel in certified aircraft by having an STC for all those engines in any aircraft they are installed in.  So YES, you will need an STC to legally run G100UL.

[EricJ]

6 minutes ago, Pinecone said:

The bottom line is, if you agree or disagree about "grade" and the ASTM standard, G100UL is BEING CERTIFIED USING THE STC PROCESS.

George is pursuing allowing his fuel in certified aircraft by having an STC for all those engines in any aircraft they are installed in.  So YES, you will need an STC to legally run G100UL.

If this really goes this way and G100UL does get approved and put in distribution under an STC, I don't think this will mean individual aircraft owners have to purchase STCs.   At least, I don't see a way that that could be practically implemented.   Nobody is going to be at a pump to check that you have the STC before you put it in, and in a situation where 100LL isn't available, it's pretty obvious what people are going to do.

As previously mentioned, Continental already shows multiple non-ASTM-specified fuels as approved on many of their TCDS, and Lycoming has a Service Instruction referenced by their TCDS citing multiple international non-ASTM-specifications as well, but for an engine installed in a certificated airframe the airframe TCDS applies.  The Mooney TCDS doesn't provide any detail other than the previously cited reference to specified "minimum grade aviation gasoline".   

 

[A64Pilot]

Besides it likely being criminal using an STC’d product without the STC, another thing that would play into it is negating your insurence by making your aircraft non airworthy.

But it all is hinged on how much is the STC, car gas STC’s have been cheap, like $1 per HP etc.

Anyone has the right to charge what they want to for their intellectual property, but gouging likely creates a lot of ill will, so I wouldn’t expect it, I expect being bent over at the pump, which could very well be done by whoever the source of the fuel is, it won’t be Gami.

However I contend that the Gami fuel is not the only viable answer, that water injection can get us there too with premium car gas, and would be what I would choose, because once the equipment is purchased it will be much cheaper, heck I’d likely do it now if it was available.

So far as an AC having any legal standing, they don’t, it’s in the name “advisory” but the FAA continues to operate as if they do, I had to comply with several AC’s in Certifying aircraft. You can argue all you want, but don’t comply with the AC and you won’t get Certified.

[GeeBee]

55 minutes ago, EricJ said:

If this really goes this way and G100UL does get approved and put in distribution under an STC, I don't think this will mean individual aircraft owners have to purchase STCs.   At least, I don't see a way that that could be practically implemented.   Nobody is going to be at a pump to check that you have the STC before you put it in, and in a situation where 100LL isn't available, it's pretty obvious what people are going to do.

As previously mentioned, Continental already shows multiple non-ASTM-specified fuels as approved on many of their TCDS, and Lycoming has a Service Instruction referenced by their TCDS citing multiple international non-ASTM-specifications as well, but for an engine installed in a certificated airframe the airframe TCDS applies.  The Mooney TCDS doesn't provide any detail other than the previously cited reference to specified "minimum grade aviation gasoline".   

 

Yes and when your airplane is in the field, gear up for whatever reason, even if not fuel related there will be the inevitable question once the fuel is sampled as crash investigations always do......where's your STC? Then you got a 91.9 problem, willful violation I might add. That will just be the start of your problems as AH64Pilot indicated.

No one is saying you have to use an ASTM fuel. You do have to use an approved fuel however in non-experimental airplanes.

[EricJ]

5 minutes ago, GeeBee said:

Yes and when your airplane is in the field, gear up for whatever reason, even if not fuel related there will be the inevitable question once the fuel is sampled as crash investigations always do......where's your STC? Then you got a 91.9 problem, willful violation I might add. That will just be the start of your problems as AH64Pilot indicated.

The legality issues are obvious, I was addressing the practicality.  If 100LL isn't available and G100UL is, you know what the majority of people are going to do if they don't have the STC and they need fuel for that last leg home or whatever.   The FAA knows this and it would likely factor into decision making, as I doubt they want to spend their time being the fuel police for individual airplanes.    I suspect this is what they're getting at when they say "drop in replacement", i.e., they don't want *any* additional headaches.

But who knows, maybe we'll have to put an additional placard at the caps with a hologram or something for proof of fee payment.   We'll see, but I think nobody knows yet how it'll play out.

[A64Pilot]

28 minutes ago, EricJ said:

 We'll see, but I think nobody knows yet how it'll play out.

I can agree with that, however what’s been keeping the Friends of the Earth’s and other lawsuits at bay for years, is that there is no other viable alternative.

I believe very shortly after such an alternative exists, then the lawsuits etc may progress, and that will give Gami a de-facto monopoly, it’s why I believe the Feds have been dragging their feet, because no manufacturers of the fuel exist, no infrastructure, no nothing, just a fuel.

We have all seen supply chain shortages, and it’s effect on prices. Imagine if you will what’s going to happen when leaded fuel is no longer produced, what are you going to pay for it, IF you can find any

[Hank]

1 hour ago, A64Pilot said:

However I contend that the Gami fuel is not the only viable answer, that water injection can get us there too with premium car gas, and would be what I would choose, because once the equipment is purchased it will be much cheaper, heck I’d likely do it now if it was available.

My Thermodynamics professors used to laugh at the idea of injecting water with fuel! They had a very profitable consulting company on the side, and removing water injection systems was part of it. Why? Water is extra (cold) mass that must be heated by the fuel; what is important to efficiency is the temperature change between intake and combustion peak, and water lowers the latter temperature.

Then there's always the problem of adding and refilling a second tank, as well as finding sources of distilled water as you fly around the country injecting it into your engine with fuel. And it's pretty much impossible for those of us with carburetors. Not sure, a lot depends on plumbing, but would your fuel injection system need to be modified to inject water AND fuel?

[GeeBee]

The idea of water injection is not power increase but detonation suppression at high power settings. On that is is superbly qualified and a success. On turbines, the issue is mass increase without burning more fuel with results in higher EGTs, equally qualified.

[Cruiser]

18 hours ago, MikeOH said:

@GeeBee

Consider a context outside the U.S.  Piston planes operate all over the world, many are of U.S. manufacture and certification, and some continue to fly under U.S. registry.  Do you honestly think all of them are operating ONLY on fuel certified to meet the ASTM D-910 standard?

If you are a realist, it is obvious they all do not.  Is it your contention that those that do not are in violation of some law or regulation?  Or, is it more probable they are operating on fuels that meet other standards or specifications (100 grade aviation fuel) of the countries/standards bodies in those locations?

In the case of Braly and his GAMI 100UL do you not think his greater than a decade development efforts have not extensively tested his fuel?  Likely well beyond the requirements of any one of many different aviation fuel standards out there.  To my knowledge this is supposed to be a "drop in" fuel with NO requirements or alterations needed whatsoever to the aircraft.  Consequently I can think of only two reasons he is not simply certifying to a particular standard (ASTM D-910 being one example):

1) He wants to shift at least some liability to the Feds; if he can get them to issue a 'blanket' STC he would have that.

2) He wants to profit from the sale of STCs (Beyond payments for royalties for the use of his 'recipe')

I certainly don't begrudge him making a profit, but I do object to being forced to purchase his STC; we are going to be paying more (likely a lot more at retail) to repeatedly buy his product.  And, if the Feds have their way (EPA/whoever bans leaded avgas), then we will be forced to buy his product regardless.  Therefore, IMO, the FAA issuing a 'blanket' STC to his company is tantamount to giving him a monopoly!!  Not exactly the function of the Feds!  Or, these days, maybe it is  If they ban leaded avgas he'll have a de-facto monopoly anyway!  To be forced to buy an STC as well??? That's simple greed right there.  Not that I hold the Feds in any high regard, but perhaps they actually have the foresight to know this and that is why no 'blanket' STC has been issued.

The above is why I am so vested in the true legal necessity of an STC.  If not legally required, we can thumb our noses at paying for his STC!

you can do that anyway. As with every STC, the owner is not going to be inspecting your airplane for the approval. 
The annual inspection probably will not refuse to issue an airworthiness sign-off 
and the airport doesn't need to see it either. 

If you want to quibble about a couple hundred dollars in aviation, when many, many other things are so expensive I have to question your logic. Oh, by the way, what GPS equipment can you legally install in your airplane without an STC ?

 

[A64Pilot]

5 hours ago, Hank said:

My Thermodynamics professors used to laugh at the idea of injecting water with fuel! They had a very profitable consulting company on the side, and removing water injection systems was part of it. Why? Water is extra (cold) mass that must be heated by the fuel; what is important to efficiency is the temperature change between intake and combustion peak, and water lowers the latter temperature.

Then there's always the problem of adding and refilling a second tank, as well as finding sources of distilled water as you fly around the country injecting it into your engine with fuel. And it's pretty much impossible for those of us with carburetors. Not sure, a lot depends on plumbing, but would your fuel injection system need to be modified to inject water AND fuel?

It’s been done since long before WWII, there is even an STC for I believe C-185’s.

Carb motors are usually low compression and can most often run car gas, no there is no significant modification required, just a plate very similar to NO2 injection, so if needed it would be an easy install there too.

I don’t believe distilled water is required and water injection is only for high power, STC I know of is above 25” manifold pressure, so T/O and first 5 min or so of climb, depending on conditions

Decent article covering water injection

https://www.avweb.com/features/the-return-of-anti-detonation-water-injection-adi/

Instead of listening to Professors, a little history may have been in order, even if the fluid was $10 a gl, I’d use only about 1 gl per flight, and more importantly to me it works just fine on 91UL, which is just good ole 100LL, without the LL. The infrastructure to supply that already exists.

Even if distilled water is used, it’s $1 a gl. I’d expect though that you would buy it pre-mixed and it would be available where fuel would be sold anyway.

‘Oh, and any engine builder will tell you that cold air / fuel is desirable, it increases the charge density. That’s why we have intercoolers and not charge air heaters.

On edit, we should have gone to ADI forty years ago, and I hope we soon will. 91UL should not cost a nickel more than 100LL, actually cheaper.

ADI systems are really simple things, spray bar and an RV water pump, and it can’t be Patented, so I’d hope several systems would pop up, and drive the cost down, you know like ADSB.

On edit, it can very significantly increase engine power, not directly, but it can allow much more timing lead or boost, because it suppresses detonation, but that’s not why I would want it, I want it to safely use lower octane fuel.

Be interesting to see if unleaded fuel does to aircraft what it did to cars, we could use “Better” oil, oil would stay cleaner, much cleaner and plug cleaning should almost go away. OCI would I expect to go to 100 hours at least etc.

Not right away of course, but unleaded fuel is a significant reason auto engines last so long now, it’s just one piece though

[MikeOH]

9 hours ago, A64Pilot said:

Besides it likely being criminal using an STC’d product without the STC, another thing that would play into it is negating your insurence by making your aircraft non airworthy.

Well, I am very interested to see how that would really play out.  To my knowledge there has NEVER been a "blanket" STC issued that requires ABSOLUTELY NOTHING be done to alter the plane and universally applicable to ANY piston aircraft that runs on 100LL.  The rules are there, ultimately, for reasons of safety.  If the FAA issues such a blanket STC, what is the safety risk of NOT having the STC?  Unlike the 94UL STCs which required proof for each model issued an STC performs properly (some aircraft are not eligible for good reasons), my understanding is that GAMI is looking for "universal approval.". Where is the risk?

And, criminal?? You must be joking...how often has the FAA gone after pilots criminally for violating an FAR?  I'm just waiting to hear all of you examples.  How many are still incarcerated?  Tears are coming to my eyes thinking about the Feds cuffing a pilot when he fills up with G100UL without that precious STC!

As far as 91.9, seems to me you are using aviation grade 100 gas in accordance with your POH.  Not seeing the violation.

[1980Mooney]

On 8/11/2022 at 9:21 PM, hypertech said:

I was looking at the type certificate and noticed that under fuel it says:

"Fuel 100LL or 100 minimum grade aviation gasoline"

 

So, now I'm thinking that as soon as GAMI or whoever offers something that is "aviation gasoline", are we good to go here as long as it is 100 octane?  

You are mixing up "Grade" with "Octane".  AVGAS 100LL and AVGAS 100 are "grades" of leaded (TEL) aviation gasoline that both have ASTM Octane ratings of 100/130  (lean mixture rating and rich mixture rating).  AVGAS 100 has twice the TEL as AVGAS 100LL.  As a result, AVGAS 100 was phased out and is no longer sold.  Your Mooney M20R TCDS is only certified for leaded grades of aviation gasoline with a minimum Grade of AVGAS 100LL and AVGAS 100.     Historically in addition to AVGAS 100 (Green color) there was AVGAS 115/145 grade that had no limit on lead content (Purple color).   It was used primarily by the military before jets took over but is still used in aviation racing engines today. (Warter Aviation)                                                            f

On 8/12/2022 at 10:41 AM, GeeBee said:

The words "100 minimum grade aviation gasoline"  refers to the green ASTM D-910 approved aviation fuel. The GAMI fuel is referenced legally as G100UL, (G100ul-12-C is the precise wording of the STC) so yes, you need an STC to use G100UL.

Absolutely correct. 

On 8/12/2022 at 6:53 PM, MikeOH said:

Hmm, I find that to be an unconvincing argument.

G100UL is an aviation gasoline with a minimum grade of 100.  It meets the TCDS requirements that state, "100 minimum grade aviation gasoline."  Just because Braly WANTS you to buy an STC doesn't mean the TCDS no longer applies!

Swift UL94 does NOT.  It would need an STC.

The TCDS for your M20F states "100LL or 100/130 octane min. grade aviation gasoline".  G100UL is not rated 100/130 per the ASTM D910 lean mixture rating and rich mixture rating.  GAMI certified G100UL as 99.6 MON.  I suspect they did it intentionally.  You need an STC.

[1980Mooney]

6 hours ago, Cruiser said:

you can do that anyway. As with every STC, the owner is not going to be inspecting your airplane for the approval. 
The annual inspection probably will not refuse to issue an airworthiness sign-off 
and the airport doesn't need to see it either. 

If you want to quibble about a couple hundred dollars in aviation, when many, many other things are so expensive I have to question your logic. Oh, by the way, what GPS equipment can you legally install in your airplane without an STC ?

I can't imagine any IA signing off an Annual if you have a tank full of yellow or light green (comingled) G100UL if you don't have the STC.  GAMI is pretty smart with the color - anyone can immediately observe if you have G100UL either fully or partially in your tanks.  A child could look at a fuel sample and tell the difference.  Without the STC the plane is not airworthy.

Why would an IA risk losing his license because the owner is cheap?  Additionally if a pilot/owner is intentionally using G100UL without the STC they are knowingly flying the plane when it is not airworthy and the owner will lose insurance coverage in the event of a claim. 

And if the Airport FBO sells it to an owner without the STC and there is an accident, the Airport FBO will be sued.  It's just like selling alcohol to underage minors.  Ignorance is not a defense.

Edited August 16, 2022 by 1980Mooney

[MikeOH]

45 minutes ago, 1980Mooney said:

I can't imagine any IA signing off an Annual if you have a tank full of yellow or light green (comingled) G100UL if you don't have the STC.  GAMI is pretty smart with the color - anyone can immediately observe if you have G100UL either fully or partially in your tanks.  A child could look at a fuel sample and tell the difference.  Without the STC the plane is not airworthy.

Why would an IA risk losing his license because the owner is cheap?  Additionally if a pilot/owner is intentionally using G100UL without the STC they are knowingly flying the plane when it is not airworthy and the owner will lose insurance coverage in the event of a claim. 

And if the Airport FBO sells it to an owner without the STC and there is an accident, the Airport FBO will be sued.  It's just like selling alcohol to underage minors.  Ignorance is not a defense.

You have a seriously vivid imagination.  Portraying the crime of the century with your hyperbole!

There will be ZERO alteration to aircraft.  It's the identical plane both before and after the purchase of a piece of paper.  Yet, your contention is lawsuits if a downed plane is found with yellow fuel in the tank???  You do realize even a frivolous law suit has to be based in at least plausible fantasy?  On exactly what basis would you connect the cause of the crash to the absence of a piece of paper?

People fly, and crash, with expired medicals and insurance still covers them, yet your outcome is denied claims over a missing STC for a drop-in-replacement fuel?  Not bloody likely.

And, seriously, you think FBOs are going to start demanding you "Show your papers!" before selling you fuel?  I guess FBOs will have to shut down self-serve fuel, too. Thanks for the laugh

[EricJ]

13 hours ago, GeeBee said:

No one is saying you have to use an ASTM fuel. 

  ...except you...

On 8/12/2022 at 6:12 PM, GeeBee said:

To be an "aviation gasoline" it has to meet ASTM D-910 standard. 

 

[GeeBee]

6 hours ago, EricJ said:

  ...except you...

 

If you read the TCDS for the engine, you will likely find other approved fuels other than ASTM specifications. For the IO-550 that is absolutely true. For Lycoming, not so much.