Primarily for general aviation discussion, but other aviation topics are also welcome.
User avatar
By MichaelP
FLYER Club Member  FLYER Club Member
#1911120
Going slightly off topic, I set up and ran a flying school in Canada.
The core aeroplanes are Katanas fitted with Rotax 912S engines.
What is the correct fuel for these engines?
Mogas!
So we buy a Tidy tank, take it to the petrol station, and fill it with Shell V Power or Chevron 95 unleaded petrol.
Is there a problem?
Has there been a problem?
There be mountains, warm summers, has there been a problem?

If I followed the general population I would be fat! I am a little into the yellow BMI, so this has to be sorted. I am careful with what I put into my body, but deviate once in a while due to the presence of cake, biccies, and anything with custard.
I am careful with what fuel I personally use and that which I feed aeroplanes with.

In Holland I had to have a stuck valve attended to: lead!
Time and money spent that could be avoided if prior to Michael the owners had fed the engine with unleaded fuel.
100LL is occasionally acceptable, and 91UL used most of the time can dissolve some of the lead build up.
By Bathman
#1915713
UL91 is now cheaper than avgas at my local airfield. Yet the two based schools are still using avgas even though all their aircraft will run and run better on the unleaded alternative.

If this is happening all over the UK I cant see much of a future for UL91
User avatar
By russp
FLYER Club Member  FLYER Club Member
#1915720
BobM wrote:Quite a bit on Avweb about UL91 and unleaded,

https://www.avweb.com/insider/faa-conti ... on-g100ul/

https://www.avweb.com/air-shows-events/ ... -page-not/


I don't see any mention of UL91 in either of those articles ... and it's articles like these that perpetuate the myth that most airplanes need a 'new' unleaded alternative to 100LL rather than already being completely able to use the existing unleaded Avgas available today. UL100 is only needed to be developed and approved for a small proportion of the GA fleet - the rest can already, and would be better off using whats available today.. UL91
Gas Guzzler, Bathman liked this
User avatar
By T67M
FLYER Club Member  FLYER Club Member
#1915879
RisePilot wrote:Sorry MichaelP, Lycoming says no ...


If you look at the whole of SI1070 (https://www.lycoming.com/service-instruction-no-1070-AB) you'll see that Lycoming say "yes" a LOT more than they say "no". Almost all engines at or below -320, and the majority up to -360, are now approved for UL91 AVGAS - but do check carefully as there are a handful of exceptions.
User avatar
By T67M
FLYER Club Member  FLYER Club Member
#1915936
I think @riverrock is just discovering that Lycoming keep updating SI1070. When that article was written, "Revision S" was current. Since then (April 2013), they have produced revisions T, U, V, W, X, Y, Z, AA and now AB. Sadly they don't seem to keep the old versions available for reference, hence the dead link in the article.
riverrock liked this
By riverrock
FLYER Club Member  FLYER Club Member
#1915937
(its possible I've mixed up my dates - I'm guessing that AB comes after S, and that article is from 2013 and the current "AB" version that is listed is from 2020 :oops: )
By Forfoxake
FLYER Club Member  FLYER Club Member
#1915950
Sherburn-in-Elmet has UL91 at £2.30 pl (4/6/22). Free landing with purchases of 40 litres of fuel (private flights only).

Also from website; Fife (Glenrothes) £2.20 pl

Unsure of current price but Currock Hill also has UL91, priced in Imp Gallons!

Balado Park also planning to get UL 91 in autumn.