Which aircraft system does NOT receive hydraulic pressure in the T-54?

In the T-54 aircraft, the yaw damper system operates independently of hydraulic pressure. This system is primarily responsible for improving the aircraft's directional stability during flight by automatically making adjustments to the control surfaces. Typically, yaw dampers use electrical signals to manipulate the control surfaces instead of relying on hydraulic systems.

On the other hand, wing flaps and prop deice systems are depending on hydraulic pressure for their operations. Wing flaps utilize hydraulic pressure to extend or retract, which alters the lift characteristics of the aircraft during various phases of flight. The prop deice system also relies on hydraulic mechanisms to effectively remove ice buildup on the propeller blades.

Thus, the correct identification of the yaw damper as the system that does not receive hydraulic pressure highlights the distinction between different aircraft systems and their operational dependencies.