Rotax and Avgas

[derekmalbon]

Hi All
We have a Eurostar fitted with a Rotax 912
Over the last 3 months it has been very dificult to find Mogas without Ethanol in our last supply has now just tested positve for ethanol.
Our home Airfield Netherthorpe does not supply the new approved UL91 Avgas but does does stock the 100 Avgas leaded product.
Rotax say Avgas is safe to use . Has anybody used Avgas in a Rotax for any lengh of time and what steps if any do you have to take to safely use it.
I'm sure other members with Rotax engines have come across this problem and i wondered how they have overcome the Mogas/Ethanol problem.
Advise/sugestions please
Derek

[John Clarke]

Rotax also say that the 912/914 engines can safely run on Mogas with up to 10% ethanol and I believe that they do in the USA but here in the UK, with the air here being far more dangerous than US air, we cannot use fuel with ethanol except (so far as I am aware) in microlights. Almost every Rotax owner in the UK is stuck between a rock and a hard place and if there's anything being done about the situation then the powers that be are keeping very quiet about it. I suspect that, when there's nothing left but Mogas with ethanol (and we must be getting close to that situation now), then we'll be allowed to use it.

Anyway, mini-rant over . Rotax recommend that if you use Avgas all the time then the service interval should be halved i.e. oil change and plug change at 50 hours (and preferably 25 hours for the plugs). Long term use of Avgas can cause problems with lead build-up on valves, con-rods and the sprag clutch. None of this is very healthy.

If you haven't already got it I can recommend the pdf at the following link:- http://www.conairsports.co.uk/downloads ... %20bal.pdf

[gasax]

As John says Rotax have said the 912 is ok on ethanol, I believe the LAA are trying to get the CAA to publish something along those lines - but as with all these things it is a bit like pushing water uphill.

5 minutes on the net will show you why the service intervals on Avgas are halved - the grey sludge build-up is very ugly.

But as the rest of the world happily uses Mogas with varying amounts of ethanol in it without problems, perhaps some rational thinking is appropriate?

[Kevin Dilks]

If your eurostar is microlight no worries use the mogas.
Murco and jet stations around leicester are ethanol free FYI.

Cheers
Kevin

[Ian Melville]

Are you sure Jest Stations don't just sell Jet A1

[ThePipster]

I tested the super unleaded at my local Esso station recently at it was negative for Ethanol. I was also pleased to see that the pump showed that it conformed to BS EN228 where as some super unleaded fuels don't.

The downside is that it is 12p a litre more than regular unleaded, but that is still 50p a litre cheaper than 100LL.

Phil

[John Clarke]

If your eurostar is microlight no worries use the mogas.
Murco and jet stations around leicester are ethanol free FYI.

Cheers
Kevin

This is where it gets really silly. A bog standard Eurostar microlight can use Mogas with ethanol in it but all you need to do is fit an electric fuel pump to the very same Eurostar, send some paperwork to the CAA and it then becomes an SEP and can no longer use the same fuel. Utterly ridiculous!

[Nigel Ramsay]

Simon Westley (Westley Aircraft) had a depressing selection of Rotax and Jabiru heads on his bench a couple of weeks ago - all with stuck valve problems due to the CAA requirement of running on Avgas in certified a/c. Mogas every time he says!

[AlanR]

Can someone please explain to me why microlights fitted with the same Rotax/Jabiru engines aren't falling out of the sky using Mogas with ethanol?
It is totally absurd that the BMAA allow it in a microlight version of the same aircraft fitted with the exactly same engine and the LAA say no it is not allowed in the very same aircraft/engine combination!

[Ian Melville]

Alan, what makes you think it is the LAA holding you back from using mogas with ethanol?

I do agree that its an outdated rule and suspect it was based on what was perceived as the weights of microlights and LAA craft. i.e. less risk to public by a lighter craft what could put down in a smaller area.

[johnsonian]

LAA allows the use of Mogas in 2 Stroke Rotax engines not just in Microlights, as per below,

"CAA have agreed that in the case of aircraft operated on Permits to Fly issued on LAA
recommendation, LAA as a CAA approved organisation may approve individual
aircraft/engine combinations for use of unleaded Mogas under CAP 747 Appendix 8 GC
4 & 5).

LAA aircraft, fitted with a two-stroke Rotax engine, have been identified as an
aircraft/engine combination eligible for approval for use with unleaded Mogas".

Regards,

Ian.

[Brian Hope]

Hi Ian, that is mogas without ethanol. Mogas with ethanol can only be used in microlights, not in SEP or SSEA. Currently, if you wish to use mogas in a Rotax two or four stroke in SEP or SSEA it must be EN228 and not contain ethanol, and that is becoming increasingly difficult to find. Hopefully we will eventually be able to use mogas with ethanol, subject to the aircraft meeting certain criteria regarding materials used in the fuel system.

[johnsonian]

Hi Brian,

Whilst I do not doubt what your saying I reread the information sheet downloaded from the LAA website and it does not mention ethanol only unleaded mogas to BS EN228 RON 95 and goes on to state that this should "provide the owners of LAA Rotax 2 stroke-powered aircraft with the
opportunity to ‘fly green’ if they should wish, as well as providing owners remote from
airfield fuel supplies the freedom to operate with readily-available fuel from the local
garage forecourt"

Ian.

[Brian Hope]

But the showstopper is:

"CAA have agreed that in the case of aircraft operated on Permits to Fly issued on LAA
recommendation, LAA as a CAA approved organisation may approve individual
aircraft/engine combinations for use of unleaded Mogas under CAP 747 Appendix 8 GC
4 & 5).

And when you check CAP 747 Appendic 8GC 4 & 5 it states:

2.1 The provisions of this Generic Concession No. 5 are limited to unleaded MOGAS that
does not contain alcohol. The BS EN228 specification allows the presence of some
alcohols without further declaration. The implementation of a European Directive is
likely to result in changes to the composition of unleaded MOGAS offered for sale in
the EU to include the alcohols permitted by the BS EN228 specification (‘Directive
2003/30/EC of the European Parliament and of the Council of 8 May 2003 on the
promotion of the use of bio fuels or other renewable fuels for transport’). Therefore,
anyone intending to use unleaded MOGAS in an aircraft should remain vigilant in
verifying that the fuel does not contain alcohol.

[johnsonian]

Hi Brian,

Many thanks for that, most useful, maybe the LAA advice sheet should be updated a little to make that point clear.

Regards,

Ian.