FAQ. Whats that hole at the back of the aircraft?

It’s the outflow valve,

It contols the cabin presurization by modulating the rate at wich the pressurized cabin air is released from the aircraft. It is controlled by two pressurization controlers.

This is selected from the pressurization control panel in the flight deck

Hear is the outflow valve from the inside, it’s behind the rear freight bay wall

And hear it is removed.

(Three electrical plugs, one bonding lead and twenty two bolts)
Now that’s what I did at the weekend!

Rgds Cking