Mogas in Rotax 912/914 engines

[Ransman 2]

Anyone know the current position regarding use of UK Mogas in Rotax 912/914s? These engines are designed to use Mogas (Avgas in emergency or if Mogas not available) but there has been much written recently about the (increasing?) amount of alcohol/ethanol present in Mogas. Does this affect the seals etc. in a Rotax?

[BackPacker]

To the best of my knowledge, the alcohol doesn't matter for the engine per se, but you need to make sure that the rest of the fuel system is up to it as well. And with mogas your C of A or permit might restrict you to the lower altitudes due to increased chances of vapour lock.

I think the UK authority on this is Skydrive. Why not give them a call? http://www.skydrive.co.uk/

[bingoboy]

Can anyone tell me how car manufacturers are or will cope with ethanol content as they do test their product in extremes ?

[Rod1]

If you check your Rotax manual it says small amounts of Ethanol is allowed but not recommended. Most Rotax installations will probably work ok, but it is specifically against the rules to use any Mogas containing ethanol in aircraft.

The PFA are investigating the issue, and I hope the restriction will be lifted for suitable installations. Fortunately, the oil companies are not keen on the Ethanol rules, and as the regulation making it compulsory does not come in until 2010, most will not introduce it before this. Some of the supermarkets have jumped the gun to get the green vote. The std Ethanol test is all you have to do to test the fuel is ok for aviation use, and I think you will find that it will not detect 5% ethanol.

Rod1

[Ransman 2]

Thanks for your replies. The guru at SkyDrive is away until next week and it will be interesting to hear what he and the PFA have to say.

Ransman 2

[happybiker]

FAA are alerting to the safety issues concerning ethanol/methonal in gasoline

http://www.faa.gov/aircraft/safety/a...a/CE-07-06.pdf

[druines]

Premium unleaded

I'm interested in fuel content/composition because of problems I have had with vapour lock.

Most forecourts now have high performance fuel with octane ratings of say 99 (RON). Does this fuel work well in Rotax, is it less volatile than premium, or are the additives not good?

The use of the word "premium" in the AD applies to just about any fuel and octane rating is often the minimum.

[Mariner9]

Fortunately, the oil companies are not keen on the Ethanol rules, and as the regulation making it compulsory does not come in until 2010, most will not introduce it before this.

Unfortunately not quite correct, the tax breaks that come into force from Sept '08 mean that its almost certain that all unleaded gasoline in the UK will have 5% biocomponent by then. (Only Tesco's does so far BTW)

However, the good news is that one of the oil majors will be using bio-ETBE instead of bioethanol. Bio ETBE is not an alcohol, and has none of the issues listed as the reasons why ethanol should not be used. (The ethanol issues are completely overstated anyway IMHO).

Cant say which oil major yet BTW, but I expect it will be in the public domain in due course.

druines: No point and a waste of money using premium Mogas in a Rotax - only engines with electronic timing/mixture controls (ie modern car engines) can benefit. Same volatility specs as normal Mogas so no bearing on vapour lock either. Premium will also have 5% biocomponent by Sept '08.

[Rod1]

The fuel situation is not looking so good. Apparently it has been worked out that the max safe level of Ethanol is 3%, which rules out most of the mogas which will be available in the near future which will contain 5%. One of the oil companies is considering producing an Ethanol free mogas, which could be used, but this would not necessarily be available at forecourts, it may be to special order only. If this is the way things go then we will have to lobby out local airfields to provide mogas or be reduced to using Avgass.

Rod1