With one engine off, wouldn’t the other be driving both rotors? I can’t imagine that would be very fuel efficient if the engine is doing a lot more work than it was designed for.
No, only one engine would be pushing. Pillows compensate by adjusting the surface controls.
Yes, with one engine out, power still goes to both rotors. There is enough power to maintain level flight at about 80 knots. Of course the one engine is using a little more fuel on one engine, less what the other engine no longer is drawing, then when both engines were online.
I would bet the USMC has figured this out with the 3 engine CH-53E. Shut one down and watch the range go up. The theory is those gas turbines use about the same amount of fuel no matter if you are pulling lots of torque or not. And one less engine
Just really curious what Boeing knew about their flight.
Gee - if that last engine goes out, we might be up here all day, lol