tmo wrote:
Isn’t there a blanket approval for EASA planes (airframes) and Lycoming SL-1070 that would make using an EN228 fuel in a lot of engine / airframe combinations?
If there was, it should be in CS-STAN, but there are only Standard Changes for 91/96UL and UL91.
boscomantico wrote:
There is a standard change only for UL91.
Also for 91/96UL.
Sounds like perhaps adding EN228 is a good candidate for a future CS-STAN update then.
That won’t happen. The point with UL91 was that it is essentially 100LL without the lead in it. That is what allowed EASA to say
“Unleaded Avgas UL 91 (according to ASTM D7547 or Def Stan 91-90) may be used if approved for the particular engine types and the installation at aircraft level is already approved for operation with conventional Avgas or Motor Gasoline (Mogas)”
EN228 fuels are too different from Avgas (not only in terms of octane), which is what wouldn’t allow this.
That explains a lot, thank you!
According to AOPA Germany, at least three European Avgas suppliers seem to have lodged formal requests with the European Commission for the continued use (beyond 1st of May 2025) of TEL in their 100LL (the deadline for that was the 1st of November 2023).
AOPA says it will likely take “the next months” for the decisions.
One has to say: who is surprised?
We shall see, as they say… Last time I remember Brussels actually do a really seriously economically damaging move, where there is no scientifically demonstrable reason whatever, was the ROHS ban on lead in solder (which cost the electronics industry billions) but the chief victim of that was the Swiss watch industry, principally Swatch at the time, but CH was not the “associate EU member” which it is today 
It may be that more planes are capable of using fuels other than 100LL, but of the planes that use lots of fuel few can. So still many litres of fuel are needed in the form of 100*L (* may be U or L or anything)
It’s the planes that go to places or carry weight.
The biggest factors are economy of scale and fuel volume discounts by the fuel suppliers. Most airfields can stock just one fuel (plus maybe Jet-A1).
And yes as you say the non-100* stuff is much lower sales volume anyway – except possibly at locations that are dominated by an aeroclub with a UL-capable fleet.
Just got this from an IAOPA mailer:
Is the bold bit really true?
It is self evident that the fuel system must have compatible materials. AIUI EASA is approving just the engines so that doesn’t deal with that and I don’t know how to deal with it in practice (for non expert users who don’t know what an o-ring is). But the rest?
I know GAMI are pushing their STC but that is just a revenue facilitator; it doesn’t imply fuel system compatibility, does it?
And how will you obtain an updated TCDS for some old plane, no longer supported?
Also is this really true, if there is no mention in the POH?
The unleaded fuels 91UL and 94UL have a lower Motor Octane Number (MON), so that may (will) change the performance of the engine compared to 100LL.
