FAA To Approve Use Of 91UL Fuel In Two-Thirds Of Piston Fleet

chemgeek said:
This will be the biggest barrier to widespread adoption. Most small airports don't have two fuel farms for avgas anymore. In the old days, you could get 80 or 100 octane avgas at many airfields, but when 100LL became available, most airports dumped the lower octane fuels like a hot rock. G100UL or its equivalent is the only widely practical solution to removing lead from aviation fuel. An airport that only sells 91UL will be in world of hurt with many of their based aircraft owners, and the potential for misfueling will be greatly increased.
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A lot dumped it because it was not available.

Back in the early 80s I was instructing at the local airport. We had 100 and 80 tanks, but could not get 80 at all. So started using it for MOGAS for a few planes with the STC.
 
FPK1 said:
The FAA will issue a fleet authorization this year that will allow more than two-thirds of the gasoline piston fleet to operate on 91UL avgas. In a news conference held to update progress on the development of an unleaded high-octane replacement for 100UL, Lirio Liu, the head of certification for the FAA, said the agency plans to issue the blanket approval as part of the initiative to get rid of lead in avgas. “We expect approximately about 68 percent of the general aviation fleet will be able to use the UL91.”
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I lost track. I guess this failed?
 
91UL is a non starter. There is capacity for only one flavor of AVGAS, and it has to be 100 Octane. And the market will not switch on its own unless it is significantly cheaper, or why bother. Thus, it will have to be a government ban on lead to drive to market to any and all 100 Octane UL.
 
Racerx said:
Exactly why swift's 100r is destined for failure
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Unless it can be / until it is certified for the high compression, turbo engines. Although Swift doesn’t seem to be in a hurry to do that. I don’t think they understand how important it is to do that.

I’m hopeful the formula is able to perform in those engines as required.
 
Half Fast said:
Or they do understand the limitations of their fuel. I think that's more likely.
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Yeah - could be that. I hope not. If it is truly 100 Octane, it should work. Hope it does. We shall see.
 
StraightnLevel said:
This^^^

If it doesn't run in the IO-550 (SR22, Columbia 400, Mooney M20, later Bonanzas, Baron, etc), it won't succeed in the market.
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And Lycoming doubled down on a 100 octane future with the io390.

The sr-20, the Tecnam p2010, rv-14, and any STC'd aircraft use the io390.



If the FAA had instituted policies earlier discouraging high octane use from the get-go, they may have gotten away with it, but every single new non-rotax aircraft that is mass-produced requires 100 aviation octane.
 
There is very little likelihood that any airport is going to stock a variety of avgas types. Therefore,

1) The fuel must be 100 octane.​
2) Any approved fuels must be completely fungible with 100LL and with all other approved unleaded fuels.​

I strongly suspect that #2 means that only one UL fuel is going to win approval. At the moment, G100UL fuel/paint stripper appears to be the only real contender.
 
WDD said:
Yeah - could be that. I hope not. If it is truly 100 Octane, it should work. Hope it does. We shall see.
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One challenge is the term "100 Octane" can be ambiguous because there are different ways to measure octane. Is that 100 RON? 100 MON? 100 (R+M)/2? 100 aviation lean (MON)? or 100 aviation rich (MON)? Or something else?
 
MRC01 said:
One challenge is the term "100 Octane" can be ambiguous because there are different ways to measure octane. Is that 100 RON? 100 MON? 100 (R+M)/2? 100 aviation lean (MON)? or 100 aviation rich (MON)? Or something else?
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100LL has an octane of 100 lean, so when we discuss the octane of UL fuel, we mean the same thing: lean.
 
Half Fast said:
100LL has an octane of 100 lean, so when we discuss the octane of UL fuel, we mean the same thing: lean.
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Is standard 100 LL avgas / 100 octane lean also 130 octane rich? I've heard avgas also called 130/100, but I've also read that 130/100 is a different fuel from 100 LL. Different fuels and additives have different sensitivity, so just because a fuel measures 100 octane lean doesn't necessarily mean it will measure 130 rich.

This doesn't matter for most engines, but it might matter for some of the high performance and vintage WW-II warbird engines. Can they run safely on 100 LL today and make their full rated power?
 
I’ve read that a lot of WWII engines needed high octane fuel to make rated power. It was a big advantage allies had over Germans, who had lower octane fuel.

Allies had 130 Octane, and even 150 Octane at end of war.
 
MRC01 said:
Is standard 100 LL avgas / 100 octane lean also 130 octane rich? I've heard avgas also called 130/100, but I've also read that 130/100 is a different fuel from 100 LL. Different fuels and additives have different sensitivity, so just because a fuel measures 100 octane lean doesn't necessarily mean it will measure 130 rich.
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The older fuels used a different nomenclature; there was 80/87, 100/130, 115/145, and some others. 100LL is a lower lead replacement for 100/130,
MRC01 said:
This doesn't matter for most engines, but it might matter for some of the high performance and vintage WW-II warbird engines. Can they run safely on 100 LL today and make their full rated power?
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No, they all have to be derated to run on the lower octane fuel.
 
MRC01 said:
Is standard 100 LL avgas / 100 octane lean also 130 octane rich? I've heard avgas also called 130/100, but I've also read that 130/100 is a different fuel from 100 LL. Different fuels and additives have different sensitivity, so just because a fuel measures 100 octane lean doesn't necessarily mean it will measure 130 rich.

This doesn't matter for most engines, but it might matter for some of the high performance and vintage WW-II warbird engines. Can they run safely on 100 LL today and make their full rated power?
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IIRC, the max MP on the P-51 was 75" (!!!) and the demo pilot took it up to about 60" for just a couple seconds on the takeoff roll before pulling it back to about 45". Got to fly it for a bit but did not dare touch the throttle. :rofl:

468504520_10169968812980105_1560342075957049988_n.jpg
 
WDD said:
Thus, it will have to be a government ban on lead to drive to market to any and all 100 Octane UL.
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More likely that it will be Innospec getting out of the business and TEL becomes unavailable at any price.

Innospec Wants To Discontinue Producing Tetraethyl Lead (TEL) By 2030​


Containing the corrosive properties of TEL production could be too costly to continue.​

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​

avweb.com

Innospec Wants To Discontinue Producing Tetraethyl Lead (TEL) By 2030

Containing the corrosive properties of TEL production could be too costly to continue.
avweb.com avweb.com
 
Interesting subject. Innospec, formerly Octel, started the process of phasing out TEL production years ago. It will be interesting to watch what happens as the 2030 deadline in the U.S. approaches. It would seem logical that they would not want significant production capacity in place for a product that has few if any customers. Unless they receive a subsidy, I suspect the TEL supply will end before the deadline.
I'm hoping that Swift 100R is successful, but the much-touted fleet test on the 172R/S is pretty meaningless as that engine only requires 91 octane.
GAMI may be the only game in town for the high compression and turbocharged engines.

I'm actively shopping for a plane, but I'm not considering anything with a potential expiration date so near in the future when it comes to fuel supply.
 
737steve said:
Interesting subject. Innospec, formerly Octel, started the process of phasing out TEL production years ago. It will be interesting to watch what happens as the 2030 deadline in the U.S. approaches. It would seem logical that they would not want significant production capacity in place for a product that has few if any customers. Unless they receive a subsidy, I suspect the TEL supply will end before the deadline.
I'm hoping that Swift 100R is successful, but the much-touted fleet test on the 172R/S is pretty meaningless as that engine only requires 91 octane.
GAMI may be the only game in town for the high compression and turbocharged engines.

I'm actively shopping for a plane, but I'm not considering anything with a potential expiration date so near in the future when it comes to fuel supply.
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The problem with 100r is you will have to derate some of these engines to make it work
 
It's frustrating that we have cars and motorcycles with a 14:1 compression ratio working just fine on gas from Walmart. Aviation, however, is stuck with 100 year-old technology because innovation is too difficult to get past the FAA and too risky to get past the lawyers. Going Experimental has some advantages.
 
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