This is my first post here, so please forgive me if I have missed something.
I am confused as to where the approval for running Total UL91 in Lycoming engines is stated.
I have read the thread on the Flyer forum and both the EASA SIB 2011-01R1 and Lycoming's Service Instruction 1070Q relating to the use of unleaded fuels.
In the EASA SIB it states:
"Unleaded Avgas UL 91 may be used, if approved for the particular engine types. No additional approval is required for the aeroplane, provided the aeroplane is already approved for operation with Avgas (according to ASTM D910, Def Stan 91-90, Mil-G-5572, GOST1012-72 or equivalent)
or Mogas and the engine is already approved to use unleaded Avgas UL 91".
Clearly Total UL91 meets ASTM D910, which is the required standard for Lycoming engines, but the Lycoming SI does not seem to approve Avgas UL 91. By my reading it only refers to Hjelmco 91/96UL as an alternative unleaded fuel to 100LL in some engines and does not specifically mention unleaded Avgas UL 91, as stated in the EASA SIB.
Am I missing something, is there another Lycoming document that specifically mentions Avgas UL 91 as produced by Total? The EASA SIB states that there are differences in the properties of Hjelmco 91/96UL and Avgas UL 91 and SI 1070Q does not appear to me to read as a blanket approval of all alternative unleaded fuels that conform to ASTM D910.