It was my understanding that was the main focus for EAGLE. But people forget there has been a certified D910 unleaded avgas on the market and flying since the early 90s from an oil company in Sweden. However, while it enjoyed EASA and Lycoming approval it never got out of the EU as I remember. As I've stated when it comes to standards and specifications it gets a bit complex for reasons I've never fully understood.
Its technically a 91/96 UL but its compatible with and replaces 100LL per the available lists. They also have a 100 UL but while its meets D910 standards its short on something else so it hasn't made it to market yet as I recall. There's additional links within the link below and point to the D910 compliance on the 91/96 UL.
Never said it was a 100 UL. Just that there was a D910 UL fuel flying for 20+ years. Regardless they have had a true 100UL since about 2006 however it causes increased fuel consumption and hasnt been released publically.
Is that the fuel (91UL) that is the topic of the original post in this thread? Or is there another 91UL?
No. The 91/96UL I'm referring to has been available, approved, and flying in the EU since 1991 I believe. I think there is a 3rd 91UL (91/98) out there for the same length of time. Neither of which ever made it to the US and other markets.
From what I've read 94UL does meet D910 but they dont market that point and went with the ASTM standard for UL avgas D7xxx. But it is harder on the high octane side. As I recall Hjelmco went with an ethanol replacement additive route to meet D910 for their 100UL however it still had performance issues the last I followed it about 10 years ago. Maybe their closer now?
FYI: if you use unleaded avgas Lycoming allows 100hr oil changes as the majority of contaminants is from the combustion bypass, ie, lead.
I believe 100LL was added for the later variants.
More than 2.
My Lycoming IO-390 215 HP can only use 100LL or the G100UL STC...
Sounds like a red pill or blue pill moment.
It’s not that they can’t use mogas, it’s that their engines haven’t been tested and approved to use it. I believe Peterson wouldn’t test and approve engines that had such small numbers made because there was no way he would ever break even doing every engine in every plane. My Cherokee 235 with a O-540 has a Peterson STC which he must of thought he would sell enough STC to make money by testing and approving it…..
My Cherokee Six wasn't approved....it got the vapor lock.
I do. No Navion is approved for autofuel, and the IO-550 in mine isn't approved on ANY airframe.
Octane and Vapor Pressure (which drives vapor lock) are not related issues. I'm sure (but don't *know*) that the folks behind 91UL are smart enough to blend it so the vapor pressure is up to 100LL standards.
No....but that wouldn't "fix" the perceived problem.....since 80% of the leaded fuel is consumed by high performance commercial aircraft.
Sorry....I was referring to the Peterson STC for Unleaded fuel. The engine is fine....but the airframe is no bueno.
Gotcha. I assume your engine has an 8.5:1 compression ratio? If that's the case, 91 UL should work for you...
It has nothing to do with the octane rating but everything to do with the vaporization pressure of the fuel. The fuel works for the engine….but not the airframe. 91UL and the G100UL would probably work fine.
