Narrative:

Crew reported there was a water leak coming from the forward galley water shutoff valve. Mechanics contacted our maintenance control with ipc (illustrated parts catalog) references and part numbers for the shutoff valve. This created a time constraint and rushed atmosphere for me knowing that maintenance control was not going to issue a deferral for it and wanted it fixed as soon as possible! Upon inspecting the aircraft; I did find that the shutoff valve was leaking and required replacement. The exterior water service panel was opened and the pressure bled off so as to depressurize the system. I then removed the valve. While I had the valve out I was required to bring it to the shop area to remove the fitting and install them on the new valve. It was during this time that ground personnel serviced the lavatory and saw that the panel was open and thinking they were doing a good thing closed it.well at that point; the water system air compressor started and began to pressurize the system and with the valve being removed; it flooded the galley and parts of the flight deck floors. Prior to the start of my maintenance action I tried to find the aircraft maintenance manual reference for the removal and replacement of the valve and I could not find it! This added to the confusion and rushed feeling since I had never replaced one before.aircraft maintenance manual chapter xx should be revised to include the removal and replacement of this very important valve. This would have provided the lock out tag out procedures for the replacement.

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Original NASA ASRS Text

Title: B737 mechanic reported a failure to lock out and tag out the potable water air compressor during a valve replacement; causing the galley and cabin to flood.

Narrative: Crew reported there was a water leak coming from the forward galley water shutoff valve. Mechanics contacted our Maintenance Control with IPC (illustrated Parts Catalog) references and part numbers for the shutoff valve. This created a time constraint and rushed atmosphere for me knowing that Maintenance Control was not going to issue a deferral for it and wanted it fixed ASAP! Upon inspecting the aircraft; I did find that the shutoff valve was leaking and required replacement. The exterior water service panel was opened and the pressure bled off so as to depressurize the system. I then removed the valve. While I had the valve out I was required to bring it to the shop area to remove the fitting and install them on the new valve. It was during this time that ground personnel serviced the lavatory and saw that the panel was open and thinking they were doing a good thing closed it.Well at that point; the water system air compressor started and began to pressurize the system and with the valve being removed; it flooded the galley and parts of the flight deck floors. Prior to the start of my Maintenance action I tried to find the Aircraft Maintenance Manual reference for the removal and replacement of the valve and I could not find it! This added to the confusion and rushed feeling since I had never replaced one before.Aircraft Maintenance Manual chapter XX should be revised to include the removal and replacement of this very important valve. This would have provided the lock out tag out procedures for the replacement.

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.