What is the operation relation between the bleed selector and ISOL valve?

The operation of the ISOL valve in relation to the bleed selector is most accurately described by stating that the ISOL valve only works when the bleed selector is in MANUAL. This is because the ISOL (Isolation) valve is specifically designed to isolate bleed air sources based on the different operational modes, and it requires a manual adjustment to permit the valve to function.

When the bleed selector is set to MANUAL, it signals the system to engage or disengage the ISOL valve depending on the aircraft's operational requirements at that moment. This ensures that the crew has direct control over the bleed air system for situations such as maintenance or abnormal conditions where isolation of systems may be necessary for safety and operational efficiency.

In contrast, the other options depict scenarios that do not align with the functional relationship between the bleed selector and the ISOL valve. For instance, stating that the ISOL valve operates in AUTO mode does not capture the essence of its dependency on manual control for operation. Similarly, the notion that the ISOL valve operates independently of the bleed selector does not accurately reflect the interdependent nature of these systems in adjusting bleed air configurations. Lastly, while the ISOL valve can indeed be overridden during emergencies, this is a separate operational consideration rather than a primary