On a 777 what would happen if the aft pressurization switch was accidentally left closed?

vas
  • On a 777 what would happen if the aft pressurization switch was accidentally left closed? vas

    The Boeing 777 has fore and aft pressurisation switches (see example here). If the aft switch was forgotten on takeoff, could this cause a loss of cabin pressurisation when the aircraft reaches altitude?

  • From my previous source in that incapacitation question:

    Two outflow valves are installed: one forward and one aft. Normally, most of the outflow is through the aft outflow valve. This improves ventilation and smoke removal. Cabin altitude and full ventilation rates can be maintained by either valve. Source

  • There is only one pressurization system for the whole aircraft. The two outflow valves regulate the airflow moving through the cockpit and cabin respectively, the intake air comes from engine bleed air, which is quite hot, and is mixed with outside ambient air to regulate the temperature through two or more heat exchangers, depending on the make and size of the aircraft. If there were two pressurization systems, one for the cockpit and one for the cabin, there would have to be a pressure bulkhead between the cockpit and the cabin, and there isn't.

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