There is almost no “mogas” (whatever “mogas” actually means) in Europe. There is car petrol which nowadays contains ethanol. But car petrol tends to involve jerrycans (unless you buy a mobile bowser truck; done that one before too) so is unviable for any plane with any kind of range. We’ve done this so many times… “Mogas” used to be a specially produced car petrol, with better QA and no funny additives. May still exist…
All turbo engines, all engines above 1:8.5 CR, many others, need 100LL. But a bigger issue is airports stocking two fuels and crippling their margins in the process.
Looking at Lycoming’s SI1070 reveals quite a few Mogas capable engines.
There is car petrol which nowadays contains ethanol
There is car petrol which doesn’t contain ethanol. Also most aero engines are partly ethanol tolerant.
a bigger issue is airports stocking two fuels and crippling their margins in the process.
Yes, that is a problem, the more so in place like France where the major players such as Total and BP were unfortunately able to impose their brand. But luckily quite a few fields do provide Mogas, and the disappearance of Avgas would probably and rapidly boost their numbers…
All of which leaves my question open: how much of the GA (discounting Jet-A1 burning toys) fleet is really Avgas dependent?
Nevertheless, assuming Avgas getting banned would for sure see some interesting political maneuvering.
Dan wrote:
Also most aero engines are partly ethanol tolerant.
The engines, yes — but not the fuel system.
how much of the GA (discounting Jet-A1 burning toys) fleet is really Avgas dependent?
It has often been said that 1/3 of aircraft need 100LL but this 1/3 burns 2/3 of all fuel.
As I posted, any engine with a CR above 8.5 needs 100LL and all turbo engines regardless of CR have remained uncertified for 91UL or “mogas”.
There is car petrol which doesn’t contain ethanol
There may still be some, but look at this in terms of people flying outside their own country, or even outside their own patch. If you remove 100LL and force the use of car petrol then you have a big problem. Standard forecourt fuel contains ethanol by Brussels directive (CH may be exempt but the UK is trying to lead the known universe in this eco BS; I am surprised they have not mandated a windmill on every petrol station, like the single ones French nuclear plants have on-site 
) and this is now 5% and pushing for 10%. Here, you have E5 and E10. E10 is junk; you just get 5-10% less MPG so why bother? Plus, the composition intentionally varies by season.
I don’t know whether the old “mogas” (lead free car petrol, quality-controlled, zero ethanol, and specially blended for GA and nobody else) still actually exists and if so where but it must now be extremely limited, to “closed communities” where there is a lot of aeroclub activity flying almost totally locally. AFAIK is has not existed in the UK for many years and I have not heard clear reports from anywhere else.
Only known (to me) example within EU
https://news.err.ee/1608078271/circle-k-to-begin-selling-ethanol-free-gasoline
We have MOGAS STC for O-200A on MS880B, with use of premium local petrol brand with ethanol.
Than removing of ethanol, test for remains, than add of additive for valves, than fly…
No impact on performance, except we are trying our best to not keep that MOGAS for long in tank.
Before the first MOGAS runs, we procured spare engine fuel pump and membranes, so far no need for that.
We are flying now with 65 euro spare for resources and around 35 euro of fuel, approx. => 100 euro/h
Aviation grade MOGAS is widely available in Germany and Switzerland (probably Austria as well) as loads of planes have the STC. I am told that also France has lots of airfields which do have MOGAS, also Slovenia and Croatia e.t.c. have it on many airfields. I reckon if the UK does not, then there are simply not enough Rotax and STC’d airframes around to make it viable. I’d guess (Dan might know more) that a fair percentage of airplanes do use this kind of Mogas all over the place.
If 100LL would be stopped, the Avgas to replace it with for most fleets would be UL91, which lots of airplanes can use without even an STC, including most of the training and touring fleet up to 180hp and more. So I would guess that if 100LL gets banned, the infrastructure which up to then helt 100LL would hold 91UL from that moment on.
The real problem would be for those who absolutely need 100LL such as the high compresson, turbo and other engines.
That’s a lot of planes, although close to zero aeroclub planes, so the effect would be much bigger in some countries than others.
However I strongly suspect, from the obvious ambiguity in these discussions, that a lot of people with a “mogas STC” do not actually have an ethanol compatible fuel system. Ethanol is nasty stuff; I have a petrol generator (2 actually) and the ethanol totally consumed (dissolved) the fuel level gauges
Peter wrote:
1/3 of aircraft need 100LL but this 1/3 burns 2/3 of all fuel
Interesting, thanks. Flying WOT ROP on heavy fuel guzzlers probably doesn’t help and probably goes a long way towards explaining those numbers.
Of course, as pointed out by @Airborne_Again the whole aircraft must be able to sustain ethanol in the fuel for the use of fuel containing some. Same goes for vapor lock prevention, and so on, many factors which have filled many a thread, also here on EuroGA.
My field is pretty typical and offers amongst others UL98… which is unleaded gasoline 98 from Avia… containing a max of 5% ethanol.
Peter wrote:
I don’t know whether the old “mogas” (lead free car petrol, quality-controlled, zero ethanol, and specially blended for GA and nobody else) still actually exists
While not specially blended for GA, ethanol-free mogas does exist. The EU mandate is not about ethanol, it’s about renewable fuels, and super-premium grades (e.g. 100 octane and higher) typically contain ETBE (or possibly other ethers, but ETBE is by far the most popular in Europe) instead of ethanol. ETBE is non-corrosive to metals and non-hygroscopic.
In particular, Benzina Verva 100 in Czechia, Aral Ultimate 102 in Germany and ÖMV Super Plus in Austria contain no ethanol or methanol (officially confirmed by the respective companies). Unfortunately, all grades of Shell V-Power are no longer ethanol-free.
Wouldn’t the simplest way be to have generalized STCs for some form of 100UL like in the US? As an in-place replacement of the whole 100LL distribution network (probably at similar price). Coupled with the ban of 100LL (which is definitely missing from the US roadmap) this could help a rapid and (mostly) smooth transition from TEL.
Engines requiring good anti-knock fuel properties will keep requiring them to stay within their design limits, and that’s the case with 100UL. Definitely not the case with 91/94UL.
