Hello!
Is it here somebody , who use to fly in TB20 UL91 gasoline?
I read that IO540C has certification with UL91. Is it true?
Can this cause it any problem?
What is the experience?
Zoltan
Have a look at this. Lycoming Service Instruction 1070S local copy
I think that this is the latest version but am not sure. Search lycoming website.
What Ben said and then you use Standard Change CS-SC202b. That should be it more or less AFAIK.
https://www.easa.europa.eu/sites/default/files/dfu/CS-STAN%20Issue%203.pdf
Ben wrote:
think that this is the latest version but am not sure. Search lycoming website.
It is not nearly the latest version.
The IO540-C4 (the TB20 has this, a -C4D5D) is 91UL approved by Lycoming as of 2013.
I don’t know anybody who flies a TB20 on 91UL, but then very few airports sell that fuel, especially since TOTAL tried to corner the market and then raised their prices to 100LL levels 
What is involved in this “standard change”, given that the fuel is engine manufacturer approved?
The conditions are stated in the document but it seems like the owner can do it. Some placards needs to be visible.
This standard change involves adding a placard saying “UL 91” next to the filler cap(s) of the plane, and adding UL91 to the approved fuel list in your AFM/POH/whatever it is called in your plane.
Best thing is, it is explicitly eligible for release to service by the pilot-owner, so no extra costs involved.
CharlieRomeo wrote:
Best thing is, it is explicitly eligible for release to service by the pilot-owner, so no extra costs involved.
But you do need to have pilot-owner maintenance in the AMP to do it…
Peter wrote:
I don’t know anybody who flies a TB20 on 91UL, but then very few airports sell that fuel, especially since TOTAL tried to corner the market and then raised their prices to 100LL levels
We’re fortunate in Sweden to have Hjelmco which produces and sells its own 91/96UL fuel (Lycoming, Rotax, EASA etc. approved) which is about €0.20/litre cheaper than 100LL and can be used by almost all engines that can use UL9. BP is also selling UL91 in Sweden, but it’s only available in a few locations.
Airborne_Again wrote:
But you do need to have pilot-owner maintenance in the AMP to do it…
That’s of course true, I falsely assumed most people would have that. But even if they don’t, it shouldn’t take more than 45 min billable time. And even that would include checking the latest revision of the Lycoming SI against the aircraft’s papers.
I have one addition regarding the fuel grade stickers: Of course any label-printer will do, but if you want nice-looking red-and green ones, you should try to send an e-mail to the TOTAL aviation fuel customer service of your country. The German one send me placards for five planes free of charge. It’s worth a try.
Edited for typos.
