Originally Posted by
piratepete
I'm told if its say a 747 then systems loss due to engine number 1 causes problems, ?....
Not quite.
I've not flown the 744 for a while so am open to correction but as I recall it performance aside a straight forward run down/ failure of number 1 ( or any one of the 4 for that matter ) shouldn't cause major problems on the 747 (400 anyway) since you shouldn't lose any major systems. I certainly wouldn't think of it as a "critical engine" in the context of this thread.
What you might have heard is that it gets a bit more interesting if for some reason you lose the #1 engine
and the associated hydraulic system ( and to emphasise on a straight forward engine failure you shouldn't) since amongst other things the #1 hydraulic system is needed to raise the nose and body gear.
HTH