Originally Posted by IFLY_INDIGO
...he guessed it is the summer season in India that is the culprit. In summers we have lot of dust in the air that settles down on this valve over a period of time and spoils its spring function. ...
The valve works with muscle pressure and have problems with muscle pressure filter pollution, BUT then it stays in the closed position. (see TFU 21.63.00.021)
Let this
AME change the valve.
BTW: "There are many other such valves in this aircraft."
