What is the role of the Outflow Valve in cabin pressurization?

• A. Regulates how much air leaks out to control pressurization
• B. Regulates how much air is pumped into the cabin
• C. Adjusts the cabin temperature directly
• D. Controls external air intake

Answer: (A)

The outflow valve is the mechanism that sets how much cabin air leaves the aircraft to the outside, and that controls cabin pressurization. The pressurization system supplies conditioned air to the cabin, and the outflow valve acts as the controlled exhaust. By opening more, it vents more air, allowing cabin pressure to drop and the differential pressure to decrease; by closing, it vents less, allowing pressure to build up. The valve is guided by the cabin pressure controller to keep the cabin at the commanded pressure and altitude. It does not pump air into the cabin, directly set cabin temperature, or control external air intake—those functions are handled by the supply side and the environmental control system.