Narrative:

Oxygen pressure in cockpit below dispatch limit on overnight inspection. Removed crew oxygen bottle from forward cargo bin and returned to hangar facility to service bottle from 1290 psi to 1825 psi. During bottle removal; noticed valve was extremely tight in the 'open' position. During servicing; thought valve took a greater amount of rotation to start the flow of oxygen; which flowed fine. Valve seemed to work fine with the exception of these observations. Completed servicing; returned to aircraft for reinstallation [of O2 bottle] and operational check; and leak check; restored access. The B737-800 departed ZZZ and during next pre-flight an abnormal needle deflection was noted. Maintenance reported the valve on the crew O2 bottle was 'not open.' to the best of my knowledge; this is what I know. I did open the valve; test the first officer's mask and verified the gauge in the cockpit read what the gauge on the bottle [showed]. There were no leaks at any removed connections by way of leak-tec [solution]. Also verified pressure prior to flight when dropping off the logbook before departure. Gauge indicated 1825 psi. I was notified of this situation four hours after shift was over. Four hours after start of shift; the aircraft was on the gate; the temperature was 25 degrees fahrenheit and windy; not a factor in my opinion; with exception to the time of day. Prior to work on this aircraft; changed a main tire and wheel assembly on another aircraft; taxied an aircraft; replaced a recline button on an aircraft; serviced engine oils on aircraft; cleaned the struts on an aircraft; checked tires on an aircraft and performed a walk-around on an aircraft. The oxygen bottle was the last work accomplished before lunch and then on to the preparation for the morning departures and aircraft deliveries. There were no other mechanics involved except for a radio call and someone stopping by to see how I was doing; and give me a ride back to the hangar. I do know for a fact the O2 bottle valve was 'not closed.' the indication in the cockpit was 1825 psi and the first officer's mask tested. I do not know if the valve was fully 'open' or malfunctioned. I do know the valve is supposed to be fully opened. I do know the valve should not be over torqued in the 'open' or 'closed' position. If the valve was not open fully; the only determination I have is this; I did have two interruptions to answer general questions and the other is the time of day. If the valve did not malfunction; I may have not opened it fully. I did check the plumbing for debris prior to reconnecting. In my 26 years of aviation; I have always believed that mistakes; errors; and oversights due to any circumstances can not happen in aircraft maintenance; that is my own opinion or goal that I try to achieve each day on the job.

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Original NASA ASRS Text

Title: A Mechanic reports removing; servicing; reinstalling a Cockpit Crew Oxygen bottle and opening the Shutoff valve on a B737-800. The aircraft then departed. During the next pre-flight; an abnormal needle deflection was noted and downline Maintenance reported the valve on the Crew Oxygen (O2) bottle was 'not Open.'

Narrative: Oxygen pressure in cockpit below Dispatch limit on overnight Inspection. Removed Crew Oxygen bottle from forward Cargo bin and returned to Hangar facility to service bottle from 1290 PSI to 1825 PSI. During bottle removal; noticed valve was extremely tight in the 'Open' position. During servicing; thought valve took a greater amount of rotation to start the flow of oxygen; which flowed fine. Valve seemed to work fine with the exception of these observations. Completed servicing; returned to aircraft for reinstallation [of O2 bottle] and Operational check; and Leak check; restored access. The B737-800 departed ZZZ and during next pre-flight an abnormal needle deflection was noted. Maintenance reported the valve on the Crew O2 bottle was 'not Open.' To the best of my knowledge; this is what I know. I did open the valve; test the First Officer's mask and verified the gauge in the cockpit read what the gauge on the bottle [showed]. There were no leaks at any removed connections by way of Leak-Tec [solution]. Also verified pressure prior to flight when dropping off the Logbook before departure. Gauge indicated 1825 PSI. I was notified of this situation four hours after shift was over. Four hours after start of shift; the aircraft was on the gate; the temperature was 25 degrees Fahrenheit and windy; not a factor in my opinion; with exception to the time of day. Prior to work on this aircraft; changed a Main tire and wheel assembly on another aircraft; taxied an aircraft; replaced a recline button on an aircraft; serviced engine oils on aircraft; cleaned the struts on an aircraft; checked tires on an aircraft and performed a Walk-Around on an aircraft. The Oxygen bottle was the last work accomplished before lunch and then on to the preparation for the morning departures and aircraft deliveries. There were no other Mechanics involved except for a radio call and someone stopping by to see how I was doing; and give me a ride back to the Hangar. I do know for a fact the O2 bottle valve was 'not Closed.' The Indication in the cockpit was 1825 PSI and the First Officer's mask tested. I do not know if the valve was fully 'Open' or malfunctioned. I do know the valve is supposed to be fully opened. I do know the valve should not be over torqued in the 'Open' or 'Closed' position. If the valve was not open fully; the only determination I have is this; I did have two interruptions to answer general questions and the other is the time of day. If the valve did not malfunction; I may have not opened it fully. I did check the plumbing for debris prior to reconnecting. In my 26 years of aviation; I have always believed that mistakes; errors; and oversights due to any circumstances can not happen in aircraft Maintenance; that is my own opinion or goal that I try to achieve each day on the job.

Data retrieved from NASA's ASRS site as of April 2012 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.