Fine, borjaracing.
Put yourself in IMC and have an engine failure. I know that I'm personally very happy that I've got a second engine which, hopefully, means that the original failure won't be critical.
It doesn't even have to be an engine. If you've only got one generator or one invertor, a failure of either of these isn't going to be very nice whilst in the gloop. Once again, it's nice to be carrying 'spares' of both.
In an ideal world, I'm sure that it would be great if we had complete redundancy throughout the aircraft ie extra gearboxes, drivetrains, tailrotors etc. It might even be technologically possible. But you're not going to be left with much effective payload left, are you? The designers have got to draw the line somewhere and two engines (and their related systems) is where that line is at the moment.
Anyway, these are concepts that manfromuncle doesn't seem to grasp when he keeps on moaning and whinging about twins. Which, by the way, was the reason for my original post.
