The 172s captured by the STC are the newest in the fleet. The R model was launched in 1996 as the first fuel injected model. It was produced through 2012 and the engine was limited to 2400 RPM and produced 160 horsepower. The S model has the same engine but its RPM limit is 2600 RPM and it's rated at 180 horsepower. According to Lycoming's Service Instruction, specifying approved fuels, that engine is the most flexible when it comes to what makes it go. In addition to 100LL and other 100 octane leaded aviation fuels, it can use 91 and 94UL aviation fuels and 93 AKI mogas. It's not clear where Swift and the FAA go from here with the 172s and future STCs.
Iâm not sure where youâre going with that Tommy. Youâre upset with AvWeb for reporting what little story there may be? Or you wish it was a bigger story to tell?
I think itâs weird that Swift obtained a limited STC (rather than an AML STC), and weirder-still that they picked a candidate aircraft/engine that doesnât need 100 octane fuel in the first place. Seems like not the target audience, and also not a step in the direction of the target audience, which should be the high-power intolerant engines that power airplanes used for business, if weâre talking about their 100R fuel.
Iâll grant that the 172 gives them a population for testing, but the testing wonât tell what needs to be told for the true customers.
Wouldnât this be typical pattern? Get approval on a relatively low threshold, but widely available product for the first approval. Test, use, show progress and then go back to the FAA for more expansion. The first approval is the hardest because there is no precedent. Nobody (at the FAA) wants their name on the approval of something novel. But once that is done, itâs only the expansion of an already approved product. A much smaller approval.
@tommy Thats a little harsh for first thing in the morning. I hope your day goes better than your comment.
Sure, it often is the âtypical patternâ, but mainly for products that arenât expected to have a wide-reaching audience for whatever reason (often cost of the product, but sometimes just limited demand). But Swift has been bad-mouthing G100UL for not having an ASTM spec and how they (Swift) are working toward one, so to come out with this as a first step seems rather underwhelming. And itâs not like there isnât precedent for a wider STC, now that G100UL has received just that.
First to market (G100UL) isnât necessarily best, but it does set a benchmark that all others need to reach or exceed, and at least at the moment, 100R is neither. I would like to see another unleaded 100-octane fuel reach the market, but if itâs going to be several years (perhaps 6 yearsâŚ) before more models are added to the STC, that really isnât good enough.
Swift says that the purpose of this fuel is to replace 100ll for all aircraft. This seems, on the surface, to be an odd step, but Iâm curious about what the next step is.
This no lead issue has been going around for how many decades and we are no closer to any resolution than we were ten years ago. What else needs to be said?
Iâm still a bit perplexed why weâre still having this discussion. GAMI crossed the finish line first. They have an STC AML for every piston engine in the fleet. I donât think they wouldâve received that from the FAA without this fuel being safe and effective for what is trying to be accomplished. The supposed issue with the leaking bladders they Swift was beating a path back and forth from their booth to the AOPA display is a non-issue; if it was a problem I feel the FAA wouldâve already clamped down on it. I know George Braly has been has been vilified for charging folks for an STC but until heâs got another avenue/revenue stream to recoup the tens of millions of dollars he spent developing this fuel, through processors licensing fees, heâs absolutely entitled to it. Why hasnât the FAA said this is the âwinnerâ and this is the fuel? I think we know why? Someone somewhere is getting their nests feathered, to keep drawing this out. If the other manufacturers want to continue to develop their own fuel, so be it, they just need to make sure itâs compatible with G100UL. If not, thatâs the product and it needs to start being processed nationwide and replacing 100LL.
Sounds like a cautious first step to broad approval.
Or at least to ASTM acceptance.
(Read the linked Aviation Week article which says âG100UL also was approved incrementally across the fleet, beginning with STC approvals for certain Cessna 172 engines and airframes in 2021.â prior to blanket STC approval.)
Recall that ASTMâs âstandardâ has gaps and needs updating, according to GAMI which has listed particular items.
I understand that the supposed problem with fuel bladders in the AOPA booth at Airventure was with age of them not fuel. AOPA got a deal to use an old airplane for little money, and got what it paid for - an old airplane.
Swift got egg on its face for pointing to the leaks, perhaps staff were redirected by company owners after that.
Our booth was very close to Swift and AOPA and it was amusing to see those Swift guys trotting back and forth with anyone they could grab ahold of and trying to denigrate GAMI. The friend I was with, a highly experienced IA, immediately took a look and basically said âitâs an old Baron; show me any old Baron and Iâll show you leaksâ. Come to find out thatâs exactly what it was. We sent one of our A&P mechanics over there to look like he was interested and they ran right over and started telling him and showing him the leaks caused by the GAMI G100UL.
I reviewed the Current AVGAS Spec VS the Game commercial spec. the differences are there, They are small mostly the Game fuel has a higher boiling point and a slightly lower Specific heat of combustion the rest is pretty much the same. BOTH of these items are not very important.Theproblem w ASTM specs is they often contain"requirements" that are very very old and are not really a requirement. Now before anyone shoot the messenger. A requirement from an engineering or scientific POV is a value that can be verified by a validated method that must be met to provide minimum performance. (Standard system engineering methodology;ogy.
IN the case of specific heat of combustionâŚthis ONLY (in the case of small changes like the 5 % in their case ). relates to specific fuel consumption . The boiling point a relic and has NO real operational import as long as the fractional vapor tests in the ball parkâŚie no diesel like properties for SI engines.
This would in any case be seen in the anti knock testing since that is conducted via ASTm spec in both of these documents.
summary the ASTM spec is NOT met .BUT the differences are somewhat meaningless to engine performance. AS TO SYSTEM compatibility that is NOT part of the ASTM spec anyway so no far calling on thatIF GAMI hold their commercial spec as a non changing standard.
Whatâs obscene is that there already are Petersen STCâs for 8 different engine manufacturers and 100 different airframes for unleaded gas for most small GA planes for over 30+ years now⌠and thatâs not news and gets no tanks at airports?
I can see how tommy is also less than gruntled at this ânewsâ.
The most important aspect of 100LL replacement is usability in ALL piston aircraft. As a whole, the flying community should not be celebrating UL94 (a 66% solution according to the Swift website), Petersenâs MoGas STC (which isnât applicable to any Lycoming fuel injected engine), or any other replacement fuel which doesnât serve the entire fleet.
Operators of lower-octane capable fuels should not be taking an âIâve got mine, f(orget) youâ attitude. We have demonstrable evidence from GAMI and now Swift that 100 octane replacement fuels are achievable. This is the progress that should be celebrated, despite the problems with ASTM approval and limited STC availability, respectively.
I have no problem with lower-octane alternative fuels or MoGas STCs, but we as a community have to realize these are not solutions to the problem of 100LL extinction facing GA.
This is a first step to much broader AML/STC and ASTM Spec and likely due to political fallout from conflict between FAA HQ and Kansas City over grant of STC to GAMI⌠More conservative folks in DC probably want to wait for ASTM spec first before releasing broader STC, but all the testing and flights done for FAA using 172R made issuing this STC a no-brainer⌠There arenât going to be any tank cars of 100R shipping soon unless some flight school has a few dozen of them in one place⌠As Master Kan used to say on Kung Fu series, âPatience Grasshopper!â