Primarily for general aviation discussion, but other aviation topics are also welcome.
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By Rod1
#1402177
The CAA have allowed the LAA to clear aircraft to run on E5 mogas. EASA has cleared aircraft to run on E5 mogas (E10 too I think). It is therefor not a question of safety provided you understand the limitations.

100LL will go, one of the key fuels that will replace it will be some form of UL91 because it is easy to produce and relatively easy to get approval. The clever chemistry required for 100UL is likely to be expensive and require a lot of work to get approval so could be very expensive. Aircraft with the ability to run on Mogas E/91UL/100LL are going to be future proof.

Rod1
By James Chan
#1402179
technical or economic reason?


To begin with it was technical, but then it became economic.
By Shoestring Flyer
#1402190
For sure 100LL will go, no question of that.....but will we all live long enough to see it go that is the question. I rather suspect it will go on for quite a while yet.
By masterofnone
#1402304
Of course...nothing will last forever...100LL will eventually go. The likelihood of 100LL going of its own accord (in the absence of regulatory sanctions) is slim to none. GA has had 30 years to retire 100LL with effectively zero progress.

Picking an unverified (though plausible) statistic, something like 30% of the US GA fleet burns 70% of the annual 100LL volume. These are likely comprised of the heavy metal end of GA that use big, turbo charged engines which have no realistic hope of running on anything less than 100 octane fuel.

UL91 can likely accommodate the lighter end of GA, but when 100LL does get banned (shortly after 100UL is made available),is hard to see where 91UL will fit in. It's only hope is if it is significantly cheaper, and this is unlikely given that the majority of fuel sales will either be in 100UL or mogas.
By peterh337
.
#1408852
"there are some incorrect assertions on that forum"

What you could do, MikeB, is to post on EuroGA and correct it, with references obviously. Then others could benefit. I believe you have a login, from previous postings there.
User avatar
By SteveN
#1440618
Just to drag this back up. Glos have stated they are not going to sell UL91 once their current stocks have gone. Evidently a MOGAS pump to replace it may not happen either. While I hate the smell of MOGAS I would hate lugging around fuel in Jerrycans even more. Not going to burn 100LL in my Rotax.

I wondered what others fields intend to do?

I'm also interested in the views of other Rotax users. What premium would you pay for a MOGAS pump?
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By Flying_john
FLYER Club Member  FLYER Club Member
#1440626
We tried Mogas in the Horizon as there is an STC to support it.

But we stopped, mainly for the reason of phase separation. We notice that the fuel we pumped out of the tanks at the end of a day (we take it out because it gets pinched by ****) and saw that it was all milky. So we havent run with it since. With Avgas price low at the moment theret didn't seem to be continuing economic reason to run either UL91 or Petrol.

John
By Maxthelion
#1440633
I would pay a 10p per litre premium to fill up on mogas at an airfield. If it was much more than that then I would then prefer to lug Jerry cans around.
By matspart3
FLYER Club Member  FLYER Club Member
#1440641
SteveN wrote:Just to drag this back up. Glos have stated they are not going to sell UL91 once their current stocks have gone. Evidently a MOGAS pump to replace it may not happen either. While I hate the smell of MOGAS I would hate lugging around fuel in Jerrycans even more. Not going to burn 100LL in my Rotax.

I wondered what others fields intend to do?

I'm also interested in the views of other Rotax users. What premium would you pay for a MOGAS pump?


Not 100% decided but, I have to say, looking likely. The biggest problem we had when we investigated MOGAS before was finding a (then, Ethanol free, supplier) who would deliver in small quantities. I suspect we'll have the same issue with E5/E10. Storage, licensing and security are also far more of an issue. That's before we've talked to the insurers about misfuelling liability.

It's on my list of things to look at next month but a 10ppl premium is probably unrealistic.
User avatar
By Pete L
FLYER Club Member  FLYER Club Member
#1440644
That's a shame. The problem for me is the summer - because of the neat little placard that says don't let the MOGAS get above 21 deg C. So it looks like AVGAS in the summer and MOGAS in the winter if UL91 is going to disappear entirely. Sywell's MOGAS shows as £1.28 at the moment - AVGAS £1.46.
By aerofurb
#1440762
Our fuel choice in order of preference for the RV-12 (Rotax 912ULS) is:

1. UL91
2. 100LL
3. MOGAS

The thought process being that:

1. UL91 and 100LL are aviation spec and quality controlled to a higher degree than MOGAS

2. The 912ULS does 'prefer' unleaded fuel but if there were any real issues with running 100LL then Rotax wouldn't certify the engine for its use. At the end of the day they want to sell engines and that is done through a number of factors - reliability being one of them. They wouldn't approve 100LL is it was actually detrimental to the engine or its operation.

Operating with more than 30% 100LL means reduced maintenance intervals. We change the oil at 50 hours anyway (all three litres of it) and the sparkplugs aren't exactly costly to replace (£4 each) if they have to be done at 100 hours instead of 200 hours.

3. Faffing about with cans and potentially stinking the car out with MOGAS is a nause, as is fuelling the RV from cans.

4. Cost is a factor but the use of MOGAS over aviation grade fuels is eclipsed by the potential quality issues and can-faffing. We have run 100LL over UL91 when the price differential meant it was £4/hr cheaper to run 100LL.

At Booker, there is normally 100LL and UL91 available. At the moment the price is the same. That said, fairly frequently there is no UL91 as they have run out and are awaiting a delivery - still supplied, I believe, from deepest France. Probably the main reason that the airfield operator keeps UL91 is that one of the company 152s is running UL91 for Lycoming's own research - and allegedly got the engine at a discounted price as part of the deal. Perhaps if it sniffs 100LL the discount will have to paid back...

The EuroStars based at Booker happily operate on 100LL and have done for many years.

Away from base, we will fill up with UL91 when it is available and we need some or a deal is to be had. With 75 litres total fuel, we tend to keep the tank topped up post flight ready for the next mission so it isn't always a necessity to refuel down route.

For the non-Rotax heritage aero engine users, the UL91 does not offer any real world advantages over 100LL to justify using it - certainly cost will play an issue here. UL91 has never been a 'cheap' option perhaps due to its geographical supply costs. Perhaps the brewer thinks that people will pay more/the same for their product. I don't think that works. The relatively slow usage of UL91 also means it doesn't follow market prices as readily as 100LL - or MOGAS (prices may go up as well as down).

The one Lycoming that really does benefit from a lead-free environment is the O-235 (C152 and PA38) that loves nothing more than to fill the 'plugs with lead deposits.

I presume Sywell MOGAS is still just that - UK sourced MOGAS and not guaranteed Ethanol free. At least we Rotax users are mostly okay with Ethanol in the fuel (up to E10) - as long as the airframe manufacturer allows it.

It's a shame that airfield operators are looking at ditching UL91 but I'm not really surprised. Why suffer the cost implications of operating more bowsers or pumps/tanks to store something? Even the big GA supporters such as Gloucester are still running a business, not a charity.
User avatar
By SteveN
#1440795
My understanding of the primary problem with 100LL in Rotax was the engine oil also lubricates the gearbox so lead in the oil coats and reduces the life of gearbox internals. Perhaps I am mistaken.

Rotax SI-912-16 recommends 25hr oil changes when operated primarily on 100LL (Section 3.3).
Last edited by SteveN on Sat Feb 27, 2016 10:44 pm, edited 1 time in total.
User avatar
By leiafee
FLYER Club Member  FLYER Club Member
#1440801
SteveN wrote:Just to drag this back up. Glos have stated they are not going to sell UL91 once their current stocks have gone. Evidently a MOGAS pump to replace it may not happen either.


That'll make my trip planning a shade more complex if it happens. I use Glos as a staging point for longer trips precisely because of the UL and there's no obvious location I could go instead.

I use avgas in a pinch but wouldn't want to end up using it for every non-local trip.

I can fill to full from home but even then once a trip goes over 1:15 each way I'm looking at a fuel stop to have any reserve,

My spur of the moment trips will probably need to reduce and I'll probably need to fuel stop at smaller strips and phone ahead to ask them to position fuel for me I suppose.
User avatar
By Sooty25
#1440834
if UL91 is the environmentally friendly way forward, maybe it needs central government to subsidise it until the volumes increase to the levels where it becomes competitive. If they can subsidise wind turbines and solar panels, why not aviation fuel, it would be for the greater good.

Subsidy would only need to be in the form of reduced tax on unleaded aviation fuel.
By aerofurb
#1440836
SteveN wrote:My understanding of the primary problem with 100LL in Rotax was the engine oil also lubricates the gearbox so lead in the oil coats and reduces the life of gearbox internals. Perhaps I am mistaken.

Rotax SI-912-16 recommends 25hr oil changes when operated primarily on 100LL (Section 3.3).


The maintenance manual calls up an inspection on the overload clutch at 600 hours when the engine operates >30% leaded fuels. All of the overload clutch fitted engines have a gearbox inspection at 1000 hours, regardless of fuel type.

The use of leaded fuels doesn't reduce the TBO of the engine or any other components (bar oil, filter or sparkplugs as previously mentioned) so I doubt that it actually reduces the life of the components. I understood that the 600 hour clutch inspection was to remove lead deposits.

Regarding the operating fluids SI-912-16 - that remains different to the maintenance manual that still calls for oil changes at 50 hours when >30% leaded fuel and 100 hours when <30% leaded fuels.

It used to be that oil changes were at 25/50 hour (leaded/non-leaded) intervals unless AeroShell Sport Plus 4 was used (that enabled the 50/00hr interval).

No one has ever been able to provide me with any info of actual failures of 912s operated on 100LL that have been caused by the operation on that fuel type. I remain content that as Rotax certifies the engine to operate on leaded fuel, then its use is not detrimental to the engine.