Narrative:

During our preflight check we discovered that when the captain or first officer mask was tested the crew oxygen pressure went to zero. The crew oxygen bottle had been replaced the night before. Maintenance was called and the crew oxygen valve was discovered to be not fully open. Maintenance opened the valve fully; safety wired it; and signed it off in the logbook.

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Original NASA ASRS Text

Title: A B737-800 Captain and First Officer discovered their oxygen mask pressures at 0 PSI during the preflight mask test and maintenance discovered the oxygen bottle valve not fully open after the bottle had been replaced the previous night.

Narrative: During our preflight check we discovered that when the Captain or First Officer mask was tested the crew oxygen pressure went to zero. The crew oxygen bottle had been replaced the night before. Maintenance was called and the crew oxygen valve was discovered to be not fully open. Maintenance opened the valve fully; safety wired it; and signed it off in the logbook.

Data retrieved from NASA's ASRS site as of July 2013 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.