When inspecting a fuel system, which state should the downstream valves of boost pumps be in?

The correct answer reflects the operational status that is essential during the inspection of a fuel system. When downstream valves of boost pumps are in an operating state, it allows for a proper flow of fuel and the verification of pump functionality. Boost pumps are designed to maintain fuel pressure and ensure that fuel reaches the engine under various conditions, even during startup or in situations where fuel demand is high.

Having the downstream valves in the operating state during inspection enables maintenance personnel to check for potential leaks, verify pump performance, and assess for any abnormal vibrations or noises that may indicate a malfunction. This state is also crucial for ensuring that the fuel system can reliably provide fuel as needed without interruptions, which is vital for the safe operation of the aircraft.

In contrast to this operational requirement, other states like dormant, idle, or disabled suggest a non-functional condition, which would not allow for adequate testing or evaluation of the fuel system's operational integrity. Thus, ensuring the downstream valves are operating is key to maintaining an effective and safe fuel system in aircraft.