What is the function of hydraulic systems in aircraft?

• A. They provide electrical power for avionics.
• B. They power actuators for flight controls, landing gear, and other systems.
• C. They generate thrust through hydraulic engines.
• D. They control fuel flow to engines.

Answer: (B)

Hydraulic systems are designed to convert fluid pressure into mechanical work, providing the force needed to move large and fast aircraft components. Because the fluid is nearly incompressible, a small pump can generate a large force at compact actuators, delivering precise, high-load motion where it’s needed. This capability is essential for powering flight-control surfaces (like ailerons, elevators, and rudders), extending and retracting the landing gear, and operating other systems such as brakes, flaps, and spoilers. In short, hydraulics give the aircraft the muscle to move critical parts reliably and efficiently.

Electrical power, thrust generation, and fuel flow control are handled by other systems, so those roles aren’t what hydraulic systems are for.