[fish314]

For the KC-135 there was a defined "critical engine failure speed" and a "non-critical engine failure speed" but there wasn't any defined "critical engine". CEFS was the speed at which a decision to continue the takeoff would take exactly the same distance as the decision to stop. Non-critical engine failure speed was just a poor name for something that was really just an adjusted refusal speed.

Of course for VMCg the worst case scenario was if you lost a downwind outboard engine (4 engine airplane), so that was the situation that was assumed for any of the engine failure stuff-- the engine lost was the downwind outboard engine. I think it was the same for VMCa, the downwind engine was the bad one to lose, not the upwind.

The reason for the downwind engine being the bad one was because the numbers assumed that you'd be able to maintain directional control on the runway and deviate a maximum distance from centerline... I haven't flown that airplane in 2 years, but I think the distance was 50 feet. So if you have a wind from the left pushing you towards the right side of the runway and then you lose a right engine you'll drift FURTHER right. If you lost a Left engine, it would counteract the wind.

I think that the long story short on this one is sometimes the manufacturer of the aircraft may use some non-standard terminology, so when in doubt reference your own aircraft's Operating regulations (whatever they are, a POH, an owner's manual, or a Dash 1).