Centaurus, I am not familiar with the 737, however on the 747 the FCU condition motor will run automatically to the flight idle position when the aircraft is in the landing configuration (flaps extended to 25deg. or more). The extra fuel supplied in this position will ensure that RPM will not fall below that required to assure proper engine acceleration capability. After touchdown the ground safety relay will signal the motor to run to ground idle with a six second delay. On a flapless landing approach, the throttles should not be retarded below 55% N1 until touchdown. For interests sake, Vref30+40 has to be bugged up and the landing run required at max ldg. wt. for the 747-200 is 10,000ft.