What is the purpose of the Isolation Valve?

• A. Allows air from any source to supply both sides of the manifold
• B. Isolates air from the cabin
• C. Controls bleed air temperature
• D. Regulates cabin pressure

Answer: (A)

The isolation valve is about routing bleed air from available sources to the environmental control system. Its job is to allow air from any bleed source to supply both sides of the air manifold, giving the packs the needed airflow even if one source isn’t available. This crossfeed capability provides redundancy and ensures continuous operation of the ECS.

This isn’t about isolating cabin air, controlling bleed air temperature, or regulating cabin pressure. Those functions are handled by other valves and components: temperature is managed by the temperature control/mixing valves, and cabin pressure is regulated by the outflow/pressure controller.