There is no possibility of any 115VAC with engs windmilling.
Well, I hate to burst the bubble....
A 744 pilot was telling me recently that he lost an engine in cruise. However, at cruise speeds, his dead engine was windmilling fast enough to produce 115Vac. He even said it took them a while to realise that they had actually lost an engine, because everything was working "normally" (he said).
I believe this was one of the interesting discoveries when BA's 747 engines flamed out with volcanic ash... They were getting a lot more electricity than was reproduced in their company's
simulators... which told them they should only be getting Standby Power.
To the gentleman/men who were asking earlier, yes, I was referring to the so-called "optional" electric pumps on #2 and #3 systems on the 744, not the 747 which has only air-driven pumps available in the air.
Some 744 electrical bus control units have logic which allows the APU generators to come online even in the air
if all four engine generators have died. However, the APU needs to be running prior to takeoff.
(Sidenote) I believe the start logic can be fooled by pulling a certain air-ground system circuit breaker (not all), but this is well outside the realm of standard operating procedures.
IF you could get the APU started and providing power, AND you had electrics pumps fitted to #2 & #3 hydraulic systems, then you could conceivably power any of the electric pumps, perhaps even the AUX pump/s (as the aircraft thinks it is on the ground).... BUT, what is the point, when you should have sufficient hydraulics for flight control from windmilling engines.
Rgds.
NSEU