UL91 is never going to work
…if it is 10% more expensive than avgas, as it is at Sleap airfield
Who would still prefer it over Avgas, and why?
No lead? There are a few engines who ould be likely to work better with UL91 than with 100LL, the O235 comes to mind. However, I don’t think the advantages outweigh the 10cents per liter.
It would if its cheaper.
At every airfield I’ve ever been associated with the flying school aircraft have been the nber 1 user of avgas. The majority of the training fleet can use ul91 and I feel its a better fuel for o200 and o235. So if it was cheaper they would use it.
But its not so its dead in the water.
Jan_Olieslagers wrote:
Who would still prefer it over Avgas, and why?
Because at my airfield 91/96UL is 10% cheaper than 100LL!
Yes but are talking the Hjelmco product, apparently, which has more attractive pricing.
Nothing to do with the Total offer. Indeed the title says UL91, not UL91/96.
Jan_Olieslagers wrote:
Nothing to do with the Total offer. Indeed the title says UL91, not UL91/96.
Is that not the same product, only from different companies?
They may be the same composition, so technically the same product, I am not into chemistry. But commercially they are obviously different. One can indeed regret that the Hjelmco product sees no wider distribution. If there’s a market for it locally, expanding upon it can only be beneficial. Commercially, that is.
The articles about UL 91 are posted some time ago,
Lycoming had released the unleaded Fuel UL91 for the Lycoming IO540 C-Series
( typical engine TB20), published on Lycomings website.
Does anybody has updated experience with it in a Lyco IO-540 C -series, esp in regards of flying > FL100 and in rgds of mixing it with Avgas?
Other differences in practical meaning ( except that its siginificant cheaper than avgas [smile])
I got UL91 offered yesterday for 1,75€/ Liter in EDVH, close to Hannover, it was 20€cents cheaper than Avgas, but finally I ve chosen Avgas due to zero experience with UL91 and I was in front of an IFR-flight in FL130.
That’s a really good Q.
Very few airports in the UK sell the stuff. I believe Gloucester EGBJ has it, though the manager has openly stated their 91UL sales are only about 10% of their 100LL sales, despite TOTAL offering totally free bowsers etc.
IMHO it should work OK in a TB20 because you are down to 75% power at FL080, and down to maybe 50% at FL130, so the chances of detonation (the real risk with unleaded) is just about zero.
91UL is just 100LL without the lead. It’s not MOGAS, or just car petrol which contains all kinds of rubbish nowadays.
Who will be the first to test it to FL200? 
For sure I won’t be doing it over water 
I have no experience with TOTAL AVGAS 91UL but this is what Hjelmco writes about their product which is very similar, the Hjemco AVGAS 91/96UL.
Hjelmco AVGAS 91/96 UL is transparent to AVGAS 100 LL with no changes to engine or airframe – just top the aircraft and fly, i.e. a drop in fuel. AVGAS 91/96 UL is approved to be mixed with AVGAS 100 LL and vice versa. It has been used for millions of flighthours in thousands of aircraft during almost every possible flight condition duirng more than 20 years. We have more than three decades of experience in producing unleaded AVGAS.
http://www.hjelmco.com/pages.asp?r_id=13395
I would have filled up with TOTAL AVGAS 91UL without any hesitation.
