B738 cabin differential pressure exceeding limits
Thread Starter
Joined: May 2018
Posts: 14
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From: Dhaka
B738 cabin differential pressure exceeding limits
Hello,
FCOM says two pressure relief valves limits cabin pressure difference from exceeding 9.1 psi. So when cabin pressure difference nears/exceeds 9.1, these relief valves open? What will be the position of outflow valve at the time?
FCOM says two pressure relief valves limits cabin pressure difference from exceeding 9.1 psi. So when cabin pressure difference nears/exceeds 9.1, these relief valves open? What will be the position of outflow valve at the time?
Joined: Jan 2018
Posts: 80
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From: Mexico
It doesnt matter. In theory for the diff px to get that high the outflow valve would be closed but it could be fully open and blocked by debris. The positive px relief valves are totally independent of the rest to the pressurization system so will respond irrespective of what is happening in the rest of the system.
Joined: Aug 2005
Posts: 1,693
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From: fairly close to the colonial capitol
Plenty of good information on the over-press and negative pressure valves in this recent Tech Log thread:
Diff between Outflow valves and Positive/Negative Pressure valves?
Diff between Outflow valves and Positive/Negative Pressure valves?
