With a B hydraulic pump in AUTO position, what will cause the pump to operate?

• A. Movements of the flaps from the 0 position
• B. Engine start sequence
• C. Landing gear extension
• D. Cabin altitude change

Answer: (A)

In AUTO, the B hydraulic pump is a demand-driven source that starts to supply pressure whenever there is hydraulic demand from the flap system. When the flaps move away from the 0 (stowed) position, the actuators need hydraulic power to extend, so sensors and the control logic sense this change and energize the B pump to meet that demand. If the flaps stay at 0, there’s no hydraulic demand, and the pump stays off, conserving power. The engine start sequence or gear extension don’t automatically trigger the B pump in this mode unless the flap system is demanding movement, so the primary trigger here is the flap movement from the 0 position.