Narrative:

Aircraft had an MEL 35-02A placard which pertains to the flight deck crew oxygen indicator being inoperative. It requires a maintenance inspection every flight to ensure that the oxygen bottle has enough oxygen for the number of pilots on the flight deck for the flight. What this MEL does not cover is a serious question as to whether the oxygen valve on the bottle is fully open. Those of you that were 737 pilots will recall a period where we had discovered airplanes with the valve not fully open and will understand the magnitude of this oversight.when performing preflight duties the pilots are required to check for a pressure drop on the oxygen indicator. If the needle stays steady you were confident the valve was open. With the oxygen gage being inoperative this safety feature is removed. MEL 35-02A does not address this at all; it only addresses the bottle being full. Therefore I am requesting that along with the bottle quantity being confirmed that we add the oxygen bottle valve be checked to confirm in the full open position to the MEL. This is an essential item of safety.

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Original NASA ASRS Text

Title: B737 Captain reported they are unable to confirm if the O2 system is operating properly if the gauge is inoperative.

Narrative: Aircraft had an MEL 35-02A placard which pertains to the flight deck crew oxygen indicator being inoperative. It requires a Maintenance inspection every flight to ensure that the oxygen bottle has enough oxygen for the number of pilots on the flight deck for the flight. What this MEL does not cover is a serious question as to whether the oxygen valve on the bottle is fully open. Those of you that were 737 pilots will recall a period where we had discovered airplanes with the valve not fully open and will understand the magnitude of this oversight.When performing preflight duties the pilots are required to check for a pressure drop on the oxygen indicator. If the needle stays steady you were confident the valve was open. With the oxygen gage being inoperative this safety feature is removed. MEL 35-02A does not address this at all; it only addresses the bottle being full. Therefore I am requesting that along with the bottle quantity being confirmed that we add the oxygen bottle valve be checked to confirm in the full open position to the MEL. This is an essential item of safety.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.