Primarily for general aviation discussion, but other aviation topics are also welcome.
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By russp
FLYER Club Member  FLYER Club Member
#1910684
Was part of a very similar discussion on FB a week or so ago - the two people who confidently stated their aircraft couldn't use UL91 unleaded AvGas were pointed to the lists showing that they in fact could and that it was almost certainly better for their aircraft. The problem seems to be the huge numbers of GA lycosauraus fliers that mistakenly believe they can only use 100LL. We need to get to the point where UL91 is the default fuel and 100LL is the second choice where airfields have the ability to stock 2 for those small numbers of aircraft who can only use 100LL.
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By GrahamB
FLYER Club Member  FLYER Club Member
#1910687
russp wrote:
> Was part of a very similar discussion on FB a week or so ago - the two
> people who confidently stated their aircraft couldn't use UL91 unleaded
> AvGas were pointed to the lists showing that they in fact could and that it
> was almost certainly better for their aircraft. The problem seems to be the
> huge numbers of GA lycosauraus fliers that mistakenly believe they can only
> use 100LL. We need to get to the point where UL91 is the default fuel and
> 100LL is the second choice where airfields have the ability to stock 2 for
> those small numbers of aircraft who can only use 100LL.

Actually we need to get to a place where GAMI’s 100UL gets approved by the FAA, and subsequently other regulators, and is distributed worldwide. Then everyone’s engine needs are satisfied.
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By Paul_Sengupta
FLYER Club Member  FLYER Club Member
#1910695
This is quite an apposite thread as I spoke to someone quite close to Flyer yesterday (I won't say who it was!) who spent a bit of time cleaning the lead out of his plugs. I suggested he may be able to use UL91 but he said he didn't know where to obtain it.

Maybe people could update this thread if there's any missing information:

viewtopic.php?f=33&t=94790
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By Sooty25
#1910786
MichaelP wrote:
> Why when 91UL is available are we putting 100LL in aeroplanes designed to
> use unleaded 71 or 80 octane in their engines?
>
>

Simple really,

60nm round trip to closest source, and they won't allow microlights in. 80nm round trip to next closest source.

2 sources of 100LL, both within 10nm round trips.
By Bathman
#1910994
And do the local flying schools use it?

My local airfield has both 100LL and UL91. Both based schools could use the unleaded fuel for all of their fleets.

But they dont because the maintenance company they both use have told them they are better running AVGAS.

A view which is shared by nearly everyone in the clubhouse.

I have even been told by the fuelers that I'm putting the wrong fuel in my low compression 1940's ditch pump.
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By MichaelP
FLYER Club Member  FLYER Club Member
#1911008
Mechanics sometimes give bad advice based on prejudice.
They are equally able to be influenced by ‘popular opinion’.
In my life I have learned that following ‘popular opinion’ is hazardous. Rather I’d prefer to operate an engine in accordance with the manual.
You have to have a very good reason for deviating from the manufacturer’s instructions.

Mechanics used to tell me that using the mixture control “will not save money”, it’s dangerous, well why was the engine fitted with it?
From my point of view, revving an engine on the ground and leaning to clear unnecessary lead through using the wrong fuel is much more damaging to an engine.

If you use 100LL then using the mixture control is essential.

We have Avgas 91UL, it is a certified AVGAS that is an alternative to using Mogas, which is itself suffering from alcoholism, which is an alternative to using leaded fuel to avoid fouled plugs, and sticking valves.
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By Paul_Sengupta
FLYER Club Member  FLYER Club Member
#1911019
Bathman wrote:
> My local airfield has both 100LL and UL91. Both based schools could use the
> unleaded fuel for all of their fleets.
>
> But they don't because the maintenance company they both use have told them
> they are better running AVGAS.

UL91 is AVGAS so no contradiction there.

Someone's probably confusing it with mogas.
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By russp
FLYER Club Member  FLYER Club Member
#1911106
Bathman wrote:
> And do the local flying schools use it?
>
> My local airfield has both 100LL and UL91. Both based schools could use the
> unleaded fuel for all of their fleets.
>
> But they dont because the maintenance company they both use have told them
> they are better running AVGAS.
>

Of course the maintenance company told them that - more work for the maintenance company !!
By Rjk983
FLYER Club Member  FLYER Club Member
#1911115
russp wrote:
> Bathman wrote:
> > And do the local flying schools use it?
> >
> > My local airfield has both 100LL and UL91. Both based schools could use the
> > unleaded fuel for all of their fleets.
> >
> > But they dont because the maintenance company they both use have told them
> > they are better running AVGAS.
> >
>
> Of course the maintenance company told them that - more work for the maintenance
> company !!


I’d have hoped that the flying school instructor’s would have taken the trouble to learn about the aircraft they fly and understand the technical aspects and manufacturers instructions.

If only there were part of the flying training syllabus dedicated to Aircraft General Knowledge…
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