The UK hub for Luscombe Aircraft across Europe 


  • Technical Chat Tips and Advice, including flying the Luscombe
Technical Chat Tips and Advice, including flying the Luscombe

Moderator: HTB

 #8851  by Rob
 Sun Jan 18, 2015 10:28 am
howell wrote:Very interesting Rob, we are not clear here in the UK if its legal to use Mogas with Ethanol in.
Here in the West of England we can no longer purchase Mogas ethanol free, best we can get is 5%.
Chris G-SAGE Luscombe 8A.

Chris, to clear: I run with ZERO ethanol! Just wanted to point out that you should ALWAYS test. Even if you have found zero ethanol with a supplier for a long period of time there simply is no guarantee that it will test ok next time because the supply chain is not regulated as with aviation. (I sold the stuff which had 5% to a car owner..)

Indeed it becomes ever harder to find ethanol free fuel. I will also look into BP here. At the moment Total in the south of the Netherlands is OK. The north is not. Suppose one has to look hard.


 #8852  by howell
 Sun Jan 18, 2015 12:04 pm
From the LAA Forum.

by G-TERN » Mon Jan 12, 2015 9:05 am

As far as I am aware, NO! I think the CAA's announcement meant that they no longer object to the use of ethanol laced fuel in principle as long as 1/ your aircraft manufacturer, 2/ your engine manufacturer and 3/ your aircraft regulatory body (the LAA) don't mind either.
As far as I am aware the LAA have NOT yet approved the use of ethanol fuel in any of their aircraft. They made an announcement last year effectively saying that the CAA's announcement gave them the green light to go ahead and look into it and conduct tests with a view to possibly approving it in the future. So at least the LAA can now make their minds up without being hampered by CAA policy.
In my personal case, even if the LAA do give it the green light in the future, I do know that Rotax already approves the 912 to use it but I don't yet know about the position of Europa with regards to ethanol.
This is a link to the announcement that the LAA made following the CAA announcement; I'm not aware of any further progress on it from the LAA yet. ... mogas.html

I apologise if any of the above is wrong, misleading or out of date - it's just how I think the situation is from what I've read over the months!
 #8854  by howell
 Sun Jan 18, 2015 12:07 pm
And this received from Brian Hope Editor of the LAA Magazine.

by Brian Hope » Mon Jan 12, 2015 5:09 pm

Jonathan is correct, this notice from CAA does not mean we can start using mogas with ethanol in aircraft cleared for plain old, common or garden but sadly no longer easy to obtain unleaded mogas. I have asked Francis about it and he has been doing some work on the criteria for aircraft to use mogas with 5% ethanol. I hope we might be able to put something in the next magazine that better explains the situation.
 #8868  by howell
 Fri Feb 06, 2015 9:49 am
by Pete Bush » Wed Dec 17, 2008 11:22 pm

Hi Tom,
I have heard a rumour that the LAA are not giving out any more Mogas exemptions at the moment as they are worried about future ethenol content.
If you did want to convert your Luscombe for Mogas use and assuming you have a Stromberg carb, probably the most important part to replace is the float needle valve as the originals have a neoprene tip that can swell in mogas and cause engine failure. Aircraft Spruce/LAS do a stainless needle and seat kit (Pt No 07-14222).
This needle is a relatively straight forward job but the seat can be more difficult, the carb float level has to be set up pretty precisely and obviously a new gasket (07-0220) fitted on completion. The disadvantage with a steel needle is that they don't seal as well as the neoprene item and can let fuel through, this is not a problem when the engine is running or if you are in the habit of turning your fuel off after flight but if you have old and leaky fuel taps then you may have a leaky carb.
You then have to consider every rubber item that the fuel contacts in your aircraft including Gascolator seal, tank caps, rubber hoses ect. Mogas tends to attack the standard aviation AN grade hoses and O rings so a mogas proof alternative has to be fitted. Viton is a relatively new kind of rubber that is mogas and avgas proof, LAS do a Viton seal replacement for the ACS type gascolator, I also replaced the O ring primer seals on G-BROO with Viton items.

The LAA used to do a check list for mogas use that your inspector signs off, I suggest you contact your inspector and/or the LAA before starting work. There is plenty to read on the LAA forum regarding fuel.

Realy good to see your Luscombe in the air again, you have both done a fantastic job.

Pete (G-BROO)
 #8869  by howell
 Fri Feb 06, 2015 9:51 am
Please find above the very helpful resume by Pete Bush from a few years back and very relevant to the current LAA reviews.
Chris G-SAGE
 #8870  by Nige
 Fri Feb 06, 2015 9:55 am
Great, thanks Chris! :salut:
 #9034  by Jeff Smith
 Sat Nov 21, 2015 11:41 am
Aside from the Ethenol issue, there is also the problem of exhaust valve seat errosion, de to the absence of lead in the mogas. I always ran my Luscome on mogas (Continental a65), without any apparent problems. However, I have just taken my Bolkow junior for its annual, and the engineer has found low compression in one of the cylinders, which he feels sure will turn out to be an exhaust valve. The engine is a Continental 0200, with only 175 hours from new. The engineer asked if I had run the engine on Mogas. In truth, I have only done 11 hours in the aircraft, but I know the previous owner did sometimes use mogas, and had even obtained appropriate certification to use it. The engineer feels sure the problem will turn out to bee exhaust valve, valve seat errosion due to the lack of lead in the mogas. This reminds me of the problems some classic car owners had when leaded fuel was phased out. E-type Jaguars were effected particularly badly, as they really did need the old 5-star fuel. The only cure for the E-type was a cylinder head rebuild with new hardened valve seats, lowered compression via a new head gasket, and a change to the ignition timing. All this allowed the engine to run smoothly, but certainly took the edge off the performance of the 3.8 litre engine (the best one!). I will not be using mogas in my 0200 any more.

I also note that someone has commented on organic growths in fuel due to the bio fuel being added during the refining process. During my career as a Transport Manager, operating large fleets of commercial vehicles, I experienced this problem first hand, particularly when we had bunkered fuel in our own tanks. Although I had filters in the tanks to prevent these growths reaching the fuel systems of the vehicles, the growths were so bad that the quickly blocked the filters. In the end i was changing the tank filters every week, and paying thousands to a specialist company to clean out the tanks every three months or so. One of the engineers from the company that cleaned the tanks told me that he had heard of an instance where a company did not have the tank filters and the organic growths reached the fuel systems of their fleet of vehicles. The end result was that two virtually new commercial vehicle diesel engines were written off, at a cost of £15,000 each. Incidentaly, he also advised me that these organic growths seem to thrive in diesel much more than petrol. So much for bio-fuel!