When the power package slide valve closes, what component remains operational?

When the power package slide valve closes, the nosewheel steering actuator remains operational because this system is typically designed to function independently of the primary hydraulic systems that control the flaps, elevator control surfaces, and main gear actuator. The nosewheel steering actuator is often prioritized to ensure that the aircraft remains maneuverable and controllable on the ground, especially during taxiing and landing.

In contrast, the other components—flaps, elevator control surfaces, and main gear actuator—are usually dependent on the hydraulic power supplied by the package. When the slide valve closes, it typically cuts off hydraulic flow to these systems, rendering them inoperative. This design choice ensures that, even in hydraulic failure scenarios, the aircraft maintains ground control to some extent, which is crucial for safety and operational effectiveness during critical phases of flight.