How are primary flight control surfaces typically moved?

The movement of primary flight control surfaces in modern aircraft is primarily achieved through hydraulically powered control units. This system utilizes hydraulic fluid to transmit force from the pilot's inputs, through the control columns, to the control surfaces themselves, such as ailerons, elevators, and rudders. The use of hydraulics allows for more efficient movement of larger and heavier control surfaces, ensuring that the necessary forces can be generated for effective aircraft control, particularly during high-speed flight.

In many aircraft systems, while pilot input is critical for control, the actual movement of the surfaces relies on these hydraulic systems, which can be more responsive and require less physical effort from the pilot compared to purely mechanical systems. Hydraulic systems also provide enhanced reliability and can incorporate redundancy features to ensure control surfaces continue to function effectively even in the event of system failures.

In contrast, while mechanical linkages exist in some older aircraft, modern designs favor hydraulic systems for their advantages in weight and performance. Similarly, electric actuators are more common in fly-by-wire systems and are often used in secondary controls or flight envelope protection systems rather than primary flight control surfaces. Thus, hydraulically powered control units are integral to the operation of primary flight control surfaces in modern aviation.