Originally Posted by
applecrumble
Hi there,
I was flying an A320 the other day and on approach at roughly 2-3,000ft there was a fairly significant change in airflow sound. I was wondering what was likely to have caused this.
Hi applecrumble,
You probably heard the fuselage
drain valves opening. See page 3.
”Cabin fuselage drain valves :
A number (approximately 15) of piston-type drain valves are fitted along the bottom line of the fuselage, to drain condensation water or other fluid leaks. They close when ∆P between the cabin pressure and the outside ambient air pressure exceeds a certain value (between 1 and 2 PSI, i.e. 70 to 140 hPa). But their effective section is small (about 50 mm2 each).”