Hi David,
Which Lycoming engines specifically are you considering? I suppose you have checked SI1070? Also take a look at EASA CS-STAN 202b and FAQ 19380.
I have contacted Lycoming in the past regarding the use of UL fuel and this was their answer (edited):
"Lycoming ran a test with a flight school operator for 4 years on a factory rebuilt O-235 using only UL91.
In general, we see the elimination of lead from fuel as a positive for many reasons. The spark plugs stay cleaner and fouling and other types of build-up is greatly reduced or eliminated. No modification to the engine is required nor are there any operational differences. Service Letter 270 and Service Instruction 1070AA are both excellent reference documents and can be found on our website. UL91 is a suitable alternative to 100LL for many engines (see SI1070AA) as we await the roll out of UL100."
Hi David,
No experience with UL 91 but years of nice operation on my Lycoming O-360 using Mogas (unleaded automotive RON 98). I have installed in my aircraft the Pertersen Autofuel STC to use Mogas, accepted by EASA. Petersen recommends once every 75 hours the use of a full 100LL tank to replace lead on the valve seats of the engine (lead acts as a cushion). Hope it helps.
The fleet of my flying club has been running on UL91 for some 10 years without any issue. The moment I got my own plane I did the paperwork to go for UL91 as well. Not all engines are eligible, see Lycoming SI1070 for that. Two remarks:
- when running in new/overhauled engines, the flying club still uses 100LL for the first 50 hours
- there aren't that many places yet that offer UL91, but as UL91 can be mixed with 100LL this is not an operational issue
Have been using UL91 in an IO360 very happily for the last few years (5+). No issues, less plug fouling. Kids at the local infants school are getting better IQ scores....
Also agree with Tom Vekemans above
My club has run Lycoming (I)O-360 engines in three aircraft on Hjelmco 91/96UL for about 5000 hours. Our experience is only positive.
Salut David Beckett,je souhaiterais faire partenariat avec vous ?
Hi David,
Which Lycoming engines specifically are you considering? I suppose you have checked SI1070? Also take a look at EASA CS-STAN 202b and FAQ 19380.
I have contacted Lycoming in the past regarding the use of UL fuel and this was their answer (edited):
"Lycoming ran a test with a flight school operator for 4 years on a factory rebuilt O-235 using only UL91.
In general, we see the elimination of lead from fuel as a positive for many reasons. The spark plugs stay cleaner and fouling and other types of build-up is greatly reduced or eliminated. No modification to the engine is required nor are there any operational differences. Service Letter 270 and Service Instruction 1070AA are both excellent reference documents and can be found on our website. UL91 is a suitable alternative to 100LL for many engines (see SI1070AA) as we await the roll out of UL100."
Hi David,
No experience with UL 91 but years of nice operation on my Lycoming O-360 using Mogas (unleaded automotive RON 98). I have installed in my aircraft the Pertersen Autofuel STC to use Mogas, accepted by EASA. Petersen recommends once every 75 hours the use of a full 100LL tank to replace lead on the valve seats of the engine (lead acts as a cushion). Hope it helps.
The fleet of my flying club has been running on UL91 for some 10 years without any issue. The moment I got my own plane I did the paperwork to go for UL91 as well. Not all engines are eligible, see Lycoming SI1070 for that. Two remarks:
- when running in new/overhauled engines, the flying club still uses 100LL for the first 50 hours
- there aren't that many places yet that offer UL91, but as UL91 can be mixed with 100LL this is not an operational issue
Have been using UL91 in an IO360 very happily for the last few years (5+). No issues, less plug fouling. Kids at the local infants school are getting better IQ scores....
Also agree with Tom Vekemans above
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