In an aircraft system, what role do actuating units play?

Actuating units are crucial components within an aircraft's hydraulic system because they convert hydraulic pressure into mechanical motion. This conversion is essential for the functioning of various aircraft systems, such as landing gear deployment, control surface movement, and flight control operations. Essentially, when hydraulic fluid is pressurized, the actuating units utilize this pressure to perform work and move mechanical parts, thereby enabling the aircraft to operate effectively.

Understanding the role of actuating units highlights their importance in flight operations, where precise and reliable movements are critical for safety and performance. The other options focus on different functions within the hydraulic system—like temperature control, fluid filtering, and performance monitoring—but they do not pertain to the specific function of converting hydraulic energy into mechanical motion, which is the primary purpose of actuating units.