A question please, about the engine controls.
Is the mechanism for matching thrust demand to engine fuel flow open loop or closed loop. What I mean is, in the event that engine EPR/N1 is not what is being commanded by the thrust levers, does the fuel control unit keep trying to increase fuel flow until it is, or does the fuel metering unit simply set a fixed fuel flow and expect the engine to accelerate to an EPR setting concomitant with it?