How do hydraulic systems provide both primary and backup power to gear actuators?

• A. Through multiple hydraulic circuits or reservoirs; cross-bleed and redundancy maintain motion if one source fails.
• B. By using a single circuit with no redundancy.
• C. By relying on electrical motors only.
• D. By using pneumatics exclusively.

Answer: (A)

Redundancy and multiple pressure sources are how hydraulic systems give gear actuators both normal and backup power. By using more than one hydraulic circuit or reservoir, the system can continue to supply motion if part of the system fails. Cross-bleed lines connect those circuits so a pump from one system can drive another, maintaining actuator pressure even during a fault. In addition, an accumulator or standby pump provides stored energy for emergency operation, ensuring the gears can still extend or retract when primary power is unavailable.

If there were only a single circuit with no backup, a failure in that path could stop gear movement. Relying on electrical motors alone wouldn’t provide hydraulic pressure, and using pneumatics exclusively wouldn’t deliver the same force and control needed for landing gear.