What is the purpose of this small square door opening on the bottom of the fuselage during flight?"
What is the purpose of the door?
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Is that not an outflow valve, for pressurisation?
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Jet-Pack (IPACS)
June 29, 2026 at 11:40 AM Changed the title of the thread from “Why?” to “What is the purpose of the door?”. -
- Official Post
That is the pressurization outflow valve. There are two of them on larger aircraft. It opens and closes as needed to adjust the cabin pressure.
