Which component controls cabin pressure by controlling airflow in and out of the cabin?

Which component controls cabin pressure by controlling airflow in and out of the cabin?

• A. Ram air inlet
• B. Outflow valve
• C. Pressurization relief valve
• D. Vent door

Answer: (B)

Controlling cabin pressure comes down to regulating how much air leaves the cabin. The outflow valve is the component that opens or closes to adjust the exhaust flow from the cabin, which in turn sets the cabin pressure by balancing the air coming from the environmental control system with what’s leaving. The cabin pressure controller commands the outflow valve to maintain the desired cabin altitude. The ram air inlet is mainly for cooling and providing ambient air to the packs, not for regulating cabin pressure. The pressurization relief valve acts as a safety device that opens if the pressure gets too high, not for normal control. The vent door handles venting in some configurations but does not regulate pressure in the normal system.

Controlling cabin pressure comes down to regulating how much air leaves the cabin. The outflow valve is the component that opens or closes to adjust the exhaust flow from the cabin, which in turn sets the cabin pressure by balancing the air coming from the environmental control system with what’s leaving. The cabin pressure controller commands the outflow valve to maintain the desired cabin altitude.

The ram air inlet is mainly for cooling and providing ambient air to the packs, not for regulating cabin pressure. The pressurization relief valve acts as a safety device that opens if the pressure gets too high, not for normal control. The vent door handles venting in some configurations but does not regulate pressure in the normal system.