Ok, I was thinking about this for a night and I'am stuck, maybe anybody can help on the subject.
The A330 FCOM says regarding Max Cabin Altitude:
- Max norm cabin ALT for flights shorter than 2.5 hours = 8000ft.
8000ft (752hPa/11PSI)-41000ft (179hPa/2.6PSI)=573hPa/8.4PSI
- Max norm cabin ALT for flights longer than 2.5 hours = 7350ft.
7350ft (772hPa/11.1PSI)-41000ft (179hPa/2.6PSI)=593hPa/8.5PSI
So my question is: Why is the greater differential pressure allowed on flights longer than 2.5 hours. My first thougt was as the structure gets stressed with higher Δp this should only be on short flights, but this is obviously wrong.
Any hints/clues? Thanks in advance for your help.
