What are the roles of the two hydraulic systems, and how do they power flight controls and landing gear?

• A. Each system powers different hydraulic circuits; they support flight controls and landing gear with redundancy to maintain control if one system fails.
• B. Both systems power the same hydraulic circuits; redundancy is not necessary.
• C. They power only landing gear.
• D. They provide hydraulic power to pressurize the cabin.

Answer: (A)

Two independent hydraulic systems provide redundancy and power to different actuator circuits. Each system has its own pump, reservoir, lines, and actuators, and they split the work between flight controls and landing gear. Flight controls (like ailerons, elevators, rudder, and spoilers) rely on hydraulic actuators to move large control surfaces with precise authority, while landing gear uses hydraulic power for extending, retracting, and locking the gear and doors.

Because the systems are separate, a failure in one doesn’t leave the airplane without hydraulic power for essential controls or the gear—the other system can still operate those functions, preserving controllability and a safe landing. This is why redundancy matters.

The other options aren’t correct because one system does not power the same circuits as the other, redundancy is indeed necessary, and hydraulic power isn’t used to pressurize the cabin (that’s done by the environmental/bleed-air system).