91/96 UL Fuel

[cessnapete]

My local airfield will shortly be dispensing the new (and 20p lt.cheaper) 91/96 UL aviation fuel.
My G reg, EASA C of A Cessna 180 has a Cont 0-470 which has the Peterson STC approval in USA for use of Mogas and 91/96 UL.
EASA have approved the use of this fuel for Mogas appoved engines. The 0-470 is approved by engine manufacturer Continental by the STC in USA.
I am unable to find any lead (excuse the pun) on how to get UK/CAA/EASA
approval to use 91/96 on G reg aircraft.
The LAA only approve engines in LAA aircraft.

Any ideas?

[Rod1]

EASA have stated that it can be used provided it is approved by the engine manufacturer. There is a list for Lyk on their website but idea for Cont. Why not ask them?

Rod1

[achimha]

You need an EASA STC. I got mine from this company (http://autofuelstc.ch/index.php?id=13&L=1) in Switzerland for about 500 Euros two years ago. Depending on the aircraft, the STC only consists of a sticker next to the fuel tank or the replacement of hoses and pumps. According to Peter's website (http://www.autofuelstc.com/autofuelstc/pa/Outside_USA.html) (not the TB20 Peter), there is only one company in Holland that sells the EASA STC today.

Overall it's great but there is a big issue: ethanol. The STC limits ethanol content to 1% and you often find that 91/96 UL fuel contains more than that. The UL engines (Rotax) can take up to 5% and you never know what the ethanol percentage will be. At our aerodrome, it ranges from 0.1% to 2%. When it's above 1%, I mix with avgas to keep it below 1% (more or less). For this to work it is important that your airfield always accurately determine the ethanol content after each delivery and clearly indicate it.

[achimha]

@Rod1: I'm pretty sure there is no way around an STC for Lycoming/Continental. The engine/airplane POH mention fuel grades that are not available anymore. The STC covers the EN228 fuel common in Europe. Also it's not just an engine issue, it also touches on the fuel system (bladder tanks, rubber hoses, pumps, etc.).

[Rod1]

Achimha are you confusing 91ul with mogas? Avgas 91UL is Avgas 100LL without the lead added. Approval is completely different to mogas.

Rod1

[Rod1]

To save a lot of retyping;

FLYER Forums • View topic - Total Avgas UL91 UK launch (http://forums.flyer.co.uk/viewtopic.php?f=1&t=71822&hilit=91ul)

The links etc should provide the official position.

Rod1

[cessnapete]

Thanks for your reply.
I spoke to three large UK engine o/haul shops ref Continental engine fuel specs, not much help.
According to their manuals the Continental 0-470A reqiured fuel is minimum 80/87!! or if not available, 100LL. Continental do not appear to know about 91/96 yet.
Using common sense, if my engine is approved by STC for UL Mogas in USA and 100LL, then 91/96UL should be fine, being 100LL without the lead.
Technically the 91/96UL is classed as Avgas not mogas, so the various air temp/ max altitude/ O ring saga applied to Mogas do not apply.
I will be first in line at Popham when the 91/96 bowser is installed!!

[chevvron]

Isn't there a problem with the ethanol 'attacking' some parts of the fuel system or is this just restricted to bowser dispensing systems?

[Rod1]

Isn't there a problem with the ethanol 'attacking' some parts of the fuel system or is this just restricted to bowser dispensing systems?

Only applies to E5 or E10 Mogas, not Avgas.

Rod1

[max roll rate]

Hi Cessnapete

i think you are being misinformed the fuel going into popham will
be the UL91 being produced by Total this is not 91/96 as produced by Hjelmco
there has been a lot of confusion relating to the 2 types of UL91
at the moment the best way to look at it is if your engine is approved for Mogas 80/87 than you should be ok ,
Total are still in discussion with the engine manufacturers
trying to get the appropriate approvals for the fuel so fingers crossed
a lot more engines will get the nod in the future

Regards Chris

[A and C]

I am sure that Continental will publish an SB or SL about UL91.

If your aircraft has a Lycoming you need to look at Lycoming Service Letter 1070Q to check if your engine can run on UL91.

EASA have issued a SIB that states you can use what the engine manufacturer specifies regardless of what the aircraft manufacturer says.

[Rod1]

List of airfields who have had deliveries of Avgas UL91 already

Barton
Compton Abbas
Dunkeswell
Henstridge
North Weald
Rochester
Turweston
Thruxton
Wellesbourne
Wolverhampton

Final stages of preparation

Popham
Gloucester - Staverton
Sleap

10 further locations WIP

Rod1

[avturboy]

Can anyone tell me about the appearance of the grade labels which will be fixed to aircraft using UL91 please? :)

[austerwobbler]

Probably a silly question " so getting ready to duck now"
But can you mix 100LL with 96UL and it still run ok ? So if you haven't got accesses to 96UL all the time you can revert back to 100 LL if you need to.

Austerwobbler

" i have a Cirrus major engine in my Auster cleard for mogas but never tried it"

[172driver]

Isn't there a problem with the ethanol 'attacking' some parts of the fuel system or is this just restricted to bowser dispensing systems?

and

Overall it's great but there is a big issue: ethanol. The STC limits ethanol content to 1% and you often find that 91/96 UL fuel contains more than that. The UL engines (Rotax) can take up to 5% and you never know what the ethanol percentage will be. At our aerodrome, it ranges from 0.1% to 2%. When it's above 1%, I mix with avgas to keep it below 1% (more or less). For this to work it is important that your airfield always accurately determine the ethanol content after each delivery and clearly indicate it.

I'd tread carefully there. While I have no experience with 91UL, I do have experience with what ethanol in car fuel can do to your fuel system. It's not a pretty sight, the stuff eats the fuel lines from the inside. At some point, fuel can't get through anymore. Annoying in a car, potentially deadly in an aircraft. Make sure not only your engine, but your entire system can use the stuff.

[peterh337]

But can you mix 100LL with 96UL and it still run ok ? So if you haven't got accesses to 96UL all the time you can revert back to 100 LL if you need to.

The two are obviously mixable because 96UL is avgas 100LL but without TEL.

So you will get an octane rating somewhere between the two.

This one hangs on the engine's detonation margin. I think the manufacturers are realising that actually it is much harder to get most engines to detonate than anybody had previously thought, so 96UL has potential to replace 100LL in perhaps all engines, with the real issue being whether anybody is going to do the tests and approve it.

Regards alcohol, I note that Socata allow up to 2% IPA in avgas, as fuel icing protection. I know nothing about this but would have thought that since IPA is alcohol, it has a similar fuel system eating potential to ethanol, and if IPA is approved at 2% then that particular fuel system is probably OK.

A lot of fuel tanks are sealed with PR-1422 (http://www.chemcenters.com/images/DATA%20SHEET/PR%201422%20B1-2.pdf) and that appears to be alcohol resistant, but that would be the hardest thing to change; the seals in the pipework can be changed easily, in most cases. But on a CofA plane you need to be following an approved process of some sort.

[Rod1]

“with the real issue being whether anybody is going to do the tests and approve it”

I understand that there are some test results covering some traditional engines due in the next few weeks. I will post more info when I get it, but it could move us quite a long way. I think getting all traditional engines approved without modification to the engine is unlikely. The expectation appears to be around 80% - which at 20ppl less than 100LL (current price difference) will be a real plus for many.

Rod1

[PA-28R]

This is my first post here, so please forgive me if I have missed something.

I am confused as to where the approval for running Total UL91 in Lycoming engines is stated.

I have read the thread on the Flyer forum and both the EASA SIB 2011-01R1 and Lycoming's Service Instruction 1070Q relating to the use of unleaded fuels.

In the EASA SIB it states: "Unleaded Avgas UL 91 may be used, if approved for the particular engine types. No additional approval is required for the aeroplane, provided the aeroplane is already approved for operation with Avgas (according to ASTM D910, Def Stan 91-90, Mil-G-5572, GOST1012-72 or equivalent) or Mogas and the engine is already approved to use unleaded Avgas UL 91".

Clearly Total UL91 meets ASTM D910, which is the required standard for Lycoming engines, but the Lycoming SI does not seem to approve Avgas UL 91. By my reading it only refers to Hjelmco 91/96UL as an alternative unleaded fuel to 100LL in some engines and does not specifically mention unleaded Avgas UL 91, as stated in the EASA SIB.

Am I missing something, is there another Lycoming document that specifically mentions Avgas UL 91 as produced by Total? The EASA SIB states that there are differences in the properties of Hjelmco 91/96UL and Avgas UL 91 and SI 1070Q does not appear to me to read as a blanket approval of all alternative unleaded fuels that conform to ASTM D910.

[HPMan]

Lycoming released Service Instruction 1070R (http://www.lycoming.com/support/publications/service-instructions/pdfs/SI1070Q.pdf)on 16 April 2012 which supercedes SI1070Q and Service Letter L199. SI1070R gives a list at Section B of those engines which are cleared at this time to use UL91. Note that you have to either use an additive in your current oil or swap to Aeroshell 15W50.

If you are operating a CofA aircraft I would recommend you discuss the use of UL91 with your CAMO before you start using it. Always nice to clear the decks beforehand - prevents getting a nasty shock (and a big bill) later on!

[peterh337]

Always nice to clear the decks beforehand - prevents getting a nasty shock (and a big bill) later on!Why would one get a shock?

HPMan - that Lyco SL doesn't appear to be new.

Re oil, for a few years I alternated between Aeroshell 15w/50 and Exxon Elite and never saw any correlation between the oil and the oil analysis. I think both are as good as each other, providing perhaps one flies regularly (once a week in my case). What I did find with Elite was that it was more susceptible to creating a brown watery sludge around the dipstick and under the rocker covers. The Shell oil doesn't do that.

[HPMan]

peterh337 - hopefully nobody would get a nasty shock by being threatened with a (big) bill. All I was advocating was for people to check with their CAMO (or your LAA Inspector if your aircraft is on that system) before switching to UL91: it prevents people getting it wrong - which does happen. And sadly there are some unscrupulous people out there who might be slightly less pragmatic about the actions to be taken if someone accidentally used UL91 in an unapproved engine. It's a good idea to double check, is all I'm saying.

As to different oils: I concur with others - there are plenty of alternatives and no, I don't work for Shell!

[peterh337]

AIUI, 91UL is just avgas without the lead, so the only risk is engine detonation, and tests done by GAMI suggests that in real life you need to work an engine awfully hard (with CHTs ~ 550F) for this to happen.

There is no risk to fuel system components.

The Swedish 96UL is more useful stuff and almost all Europe based GA pistons can run on it, but it isn't sold outside Sweden AFAIK.

The various "100UL" propositions involve additives which any refinery can put in but they bring varying risks to fuel system components. And since most planes currently flying are orphans in terms of manufacturer support, this is a tricky area.

[achimha]

At the Aero show in Friedrichshafen, I talked to an engineer from Lycoming who used to travel the world for engine failure investigation. I questioned him on detonation and he said that they have only seen it when several things went wrong at the same time. One contributor is very high CHTs as peterh337 mentioned and apparently even worse is incorrect magneto timing.

I tried to find out how large the detonation margin is and while trying to be not specific (lawyers...), I understood that even for the non/not yet certified engines, it is virtually impossible to experience detonation with UL91.

His recipe was simple: make sure the magneto timing is right and do not lean above 75% HP. Below 75%, lean as you like.

Having no kerosene/diesel story, it is not a surprise that Lycoming is actively promoting UL91 and the like.

[peterh337]

Based on all that I've read, the above does not suprise me at all.

In any normal ops, one gets nowhere near the CHTs required for detonation.

I can however imagine there are people out there who do manage it, due to stupid operating practices (like climbing at Vx all the way to cruise level) combined with having no engine instruments.

The highest CHT I have ever seen on mine was 430F and that was departing from Turkey at +35C, after a long wait on the ground with the engine running, and having to climb fairly steeply as well. And the TB20 does suffer from less than great engine cooling. Normally one doesn't exceed 400F; ~360F in cruise.

The strange thing is that TOTAL seem to be charging almost the same for 91UL as for 100LL. I expect they are hoping to push down 100LL volumes and once enough airfields stop stocking it, they can then screw the market.

[achimha]

The strange thing is that TOTAL seem to be charging almost the same for 91UL as for 100LL. I expect they are hoping to push down 100LL volumes and once enough airfields stop stocking it, they can then screw the market.

At the Total booth, they told me that there are currently two companies in Europe producing AVGAS: Total in France and Shell in Holland (they meet once a month for breakfast to agree on the price). Production in the UK stopped some time ago. In Total's terminology, 91UL is AVGAS. The number 91 is MON (motor octane number) versus the RON (researched octane number) common for car fuel which tends to be higher. The 100 octane fuels that Shell and others try to sell across Europe only have a MON of 88.

So 91UL is similar to 100LL and therefore about as costly/inexpensive to produce as 100LL.

[peterh337]

In that case, why don't Lyco just approve 91UL for all their engines?

[achimha]

In that case, why don't Lyco just approve 91UL for all their engines?

The Lycoming guy said it requires individual testing. They are planning to add more, at least all engines that are certified for the Hjelmco AVGAS. However, we will probably not see the turbo/high-compression engines. I did not understand the specific reasons for that.

[peterh337]

Wouldn't it be funny if it turned out that actually none of the Lyco/Conti engines needed 100LL after all?

GAMI tested the worst of them all (some TSIO-550) and had a lot of problems making it detonate, being able to do it only with CHTs of 550F+. They have written this up somewhere...