4.) What causes the Standby Hydraulic System to automatically activate?
1) During critical phases of flight (flaps extended, and either in flight, or on the ground with wheel speed greater than 60 KIAS), it will activate if low pressure is detected in hydraulic systems A and/or B.
Note: Auto operation does not deactivate the flight control low pressure light.
Note: When airborne and the flaps are retracted, the standby pump shuts off and the Standby Rudder Shutoff valve closes (Standby Rudder ON light extinguishes).
2) Force Fight Monitor triggered.
Reference: FRM Chapters 9 & 13