Swift 100R is now ASTM

[Ibra]

Swift 100R is now ASTM,

https://www.aopa.org/news-and-media/all-news/2025/september/04/swift-earns-astm-approval-of-100-octane-unleaded

By far the most promising for European flyers: it's already sold in Germany and EASA approved, it's used for PPL training in C172S by one school.

 

Edited Friday at 11:29 AM by Ibra

[toto]

Nice 

[GeeBee]

The question remains....will it work in the big bore engines.

[hazek]

39 minutes ago, GeeBee said:

The question remains....will it work in the big bore engines.

And if it has any material compatibility issues. I hope the answer is good for both these issues. I really do.

[Ibra]

1 hour ago, GeeBee said:

The question remains....will it work in the big bore engines.

For engine, I am sure it works nicely in 200hp NA engine like mine, for "big bore turbo" 300hp, well it has MON 100 Octane index, what else required? or missing? 

For airframe, being ASTM makes it on tight tolerances when it comes to aromatics, hence, reduces the surprise element when it comes to material compatibility 

There are empirical data that it worked on Swedish registered SR22 (G5 with 310hp NA engine), also in 280hp uncertified machine, however, these fall under use at own risk.

For someone in Europe, the most important thing, it's "Avgas 100 Octane, no lead", so no issues producing, importing, storing in airports, wr love labels down here [*] and this one has the right label and it seems to work 

[*] as it's an "ASTM Avgas", it's easy to process by authorities, at least they know how to tax it, while some "STC juice" is likely to be hard to process, no one knows how to tax non-ASTM fuels in EU/UK? so one can't have it 

Edited Friday at 01:27 PM by Ibra

[N201MKTurbo]

The Lycoming IO-360 is one of the highest strung engines out there. It is making 50HP per cylinder. There are not many engines out there that make more. That turbo beast you mention is only making 52.5HP per cylinder.  But it has more displacement 91.6 cu in vs 90 for the IO-360, so HP/cu in is very close.

[GeeBee]

13 minutes ago, Ibra said:

For engine, I am sure it works nicely in 200hp NA engine like mine, for "big bore turbo" 300hp, well it has MON 100 Octane index, what else required? or missing? 

Full detonation testing on a big bore engine. (Which is an FAA requirement)

Also hp per cylinder is not the only measure There are issues of volumetric efficiency and effectiveness. 

I am not saying it won't work, I'm saying it needs test results that has not been revealed.

[Ibra]

3 minutes ago, N201MKTurbo said:

The Lycoming IO-360 is one of the highest strung engines out there. It is making 50HP per cylinder. There are not many engines out there that make more. That turbo beast you mention is only making 52.5HP per cylinder. Not much more.

I was not thinking in terms of hp per cylinders, it's good to know.

[IvanP]

Looks like a positive development. Let's hope it will be a workable solution.

[EricJ]

1 hour ago, hazek said:

And if it has any material compatibility issues. I hope the answer is good for both these issues. I really do.

The benefit of a consensus standard like ASTM is that it has had eyes on it and approval by a very broad set of stakeholders, including engine and airframe manufacturers, refiners, distributors, etc., etc.  The result is that the likelihood of post-deployment issues goes way, way down. 

This contrasts significantly to the STC process where one guy can do all those functions including being the DER for the FAA.

[Wingover]

Have you seen the price per L in Europe for it already?  Curious if it's the same as normal avgas?

[Ibra]

26 minutes ago, EricJ said:

The benefit of a consensus standard like ASTM is that it has had eyes on it and approval by a very broad set of stakeholders, including engine and airframe manufacturers, refiners, distributors, etc., etc

Indeed, not to forget thousands of volunteers, researcher or non profit players who peer-review most stuff in "open source". 

Getting through is difficult compared to getting through FAA STC...

 

1 hour ago, GeeBee said:

Full detonation testing on a big bore engine. (Which is an FAA requirement)

I imagine FAA has own testing, but I'm not sure how it differs from 100 MON specs requment plus detonation/knock testing as per Avgas ASTM D6424?

For UL94, I think UND school saw valve and detonation issues in their Archers as they run their engines on 450F with peak EGT at 75% power, I would never ever do that even with 100LL? you need a monkey flying the aircraft 

Detonation is rarely a concern for pilots who manage their engines, keep CHT < 380F (we even used auto-fuels in Archer with Petterson STC for 8 years, no issues).

[Ibra]

3 minutes ago, Wingover said:

Have you seen the price per L in Europe for it already?  Curious if it's the same as normal avgas?

I once called the airport, they referred to the school "who sells it" and they quote the same price as Avgas 100LL, they had bulk order and lot of paperwork, I expect it to get cheaper if they have more volumes and wide usage (as we are told sourcing TEL and associate paperwork is getting expensive). 

If it's used by an ATO, it's cheaper 

In Germany, UL91 is 0.3€/L cheaper than 100LL 

In France, UL91 and 100LL are the same prices 

[N201MKTurbo]

I hope they can get it to market for the same price as 100LL. I hope it has less issues than G100UL

[Fly Boomer]

1 hour ago, EricJ said:

This contrasts significantly to the STC process where one guy can do all those functions

I haven't been following this issue because of the poor signal to noise ratio, but the press release says Swift fuels were released under STC.  How does that "contrast significantly"?

[Ibra]

37 minutes ago, Fly Boomer said:

but the press release says Swift fuels were released under STC.  How does that "contrast significantly"?

Swift pushed 100R with FAA for C172S STC with company specs (this was a year ago). In parallel, they worked with stakeholders for ASTM approval (this is recent) for their "STC route", now they have an option to get it through PAFI...

There are two main routes to get fuel inside aircraft, the "STC route with company specs" (regulatory and airworthiness requirement) and "PAFI route with ASTM specs" (consumer, industry, regulatory requirement), the latter is way more demanding and involve more parties, there is a middle route that is also very demanding is STC with ASTM specs.

VPRacing are working on last stage for their "PAFI/ASTM route"

It's complicated, hope this graph helps: G100UL is "STC with GAMI company specs" while 100R is "STC with ASTM specs" 

 

Edited Friday at 04:56 PM by Ibra

[GeeBee]

1 hour ago, Ibra said:

Indeed, not to forget thousands of volunteers, researcher or non profit players who peer-review most stuff in "open source". 

Getting through is difficult compared to getting through FAA STC...

 

I imagine FAA has own testing, but I'm not sure how it differs from 100 MON specs requment plus detonation/knock testing as per Avgas ASTM D6424?

For UL94, I think UND school saw valve and detonation issues in their Archers as they run their engines on 450F with peak EGT at 75% power, I would never ever do that even with 100LL? you need a monkey flying the aircraft 

Detonation is rarely a concern for pilots who manage their engines, keep CHT < 380F (we even used auto-fuels in Archer with Petterson STC for 8 years, no issues).

Because it is an STC, detonation testing is the responsibility of the STC applicant, not the FAA. Swift needs to get a test cell with full instrumentation including knock sensors. Lots of detonation is undetected by the operator without sensitive knock sensors. Equally so the FAA requires a 12% detonation margin. The anecdotal fact that a Cirrus ran, "detonation free" means nothing in certification.

The hp/cylinder is equally meaning less. Cylinders have different volumes, head designs, piston tops, intake and exhaust efficiencies. There is a reason why "It's a Hemi" actually has meaning in ME terms. 

There are few test cells designed to detect detonation and believe it or not, the best test cell in the world is owned by.........GAMI.

[Ibra]

18 minutes ago, GeeBee said:

There are few test cells designed to detect detonation and believe it or not, the best test cell in the world is owned by.........GAMI.

No question about that ! 

It's fair to say that 100R may have more challenges with "stressed engines" while G100UL seems to have more challenges with "older airframes". I am sure there are various trade-off? I have fuel A that reduce metals wear by 50% (potentially increasing TBO) and reducing spark plugs fouling, prevents pre-ignition and reduces engine maintenance costs, then I have fuel B that reduces my airframe and pipelines wear, preserve paint and does not require rank reseal. 

Hopefully we will be allowed to mix both depending on what a "consumer" care about? takeoff or cruise? 

Edited Friday at 05:23 PM by Ibra

[Fly Boomer]

1 hour ago, Ibra said:

It's complicated

No kidding.  I'll give it a try after it's been run about 10,000 hours at high MP in big-bore turbocharged engines.

[EricJ]

1 hour ago, Fly Boomer said:

I haven't been following this issue because of the poor signal to noise ratio, but the press release says Swift fuels were released under STC.  How does that "contrast significantly"?

It now has an ASTM standard associated with it that it can claim compliance to.    This is relevant to acceptance in the entire production and distribution chain as well as insurability of the various pieces.  

[GeeBee]

I agree that an ASTM standard is important to production and distribution, but face it, we could have an ASTM standard for rubber chickens. The question is, can you burn it in your engine?

[UteM20F]

9 minutes ago, EricJ said:

It now has an ASTM standard associated with it that it can claim compliance to.    This is relevant to acceptance in the entire production and distribution chain as well as insurability of the various pieces.  

I think you're right, in that Swift can now put 100R at all the airfields they want, with support of the big distributors, big oil companies, and even the airframe manufacturers.  But end users can only pump it into a few 172s, and only after they've purchased the STC.  So G100UL is still the only unleaded option for my IO-360-AIA.  Please correct me if I misunderstood.

[varlajo]

17 minutes ago, UteM20F said:

I think you're right, in that Swift can now put 100R at all the airfields they want, with support of the big distributors, big oil companies, and even the airframe manufacturers.  But end users can only pump it into a few 172s, and only after they've purchased the STC.  So G100UL is still the only unleaded option for my IO-360-AIA.  Please correct me if I misunderstood.

You are correct.

[EricJ]

32 minutes ago, UteM20F said:

I think you're right, in that Swift can now put 100R at all the airfields they want, with support of the big distributors, big oil companies, and even the airframe manufacturers.  But end users can only pump it into a few 172s, and only after they've purchased the STC.  So G100UL is still the only unleaded option for my IO-360-AIA.  Please correct me if I misunderstood.

Right now that's correct.  I suspect that the ASTM standard will open a lot of doors for further acceptance, but you're right that we have to wait for that.    Engine and airframe manufacturers would have participated in the ASTM standard development, so they will already have a head start on whatever its limitations might be to know how broadly approvals should go.    It would be highly unlikely for them to spend time on development of a standard that is limited to only a few makes/models, so I expect it'll broaden in time.   I hope we don't have to wait too long to see the details.

[Ryan ORL]

4 hours ago, Ibra said:

Detonation is rarely a concern for pilots who manage their engines, keep CHT < 380F (we even used auto-fuels in Archer with Petterson STC for 8 years, no issues).

I think it could be quite a concern with this fuel, however.  From what I've read about it thus far, its MON is lower than 100LL and G100UL (neither of which are actually 100 in reality, but higher), which would significantly reduce detonation margins in my engine (IO-360-A3B6) for example.  Whereas previously detonation might only occur >25" MAP and at certain temperatures, it is very easy to imagine it occurring at previously-conservative values.