Two Mechanics describe their involvement with the servicing of a B737-800 Crew Oxygen Bottle.
Synopsis
Two Mechanics describe their involvement with the servicing of a B737-800 Crew Oxygen Bottle.
Narrative
Outside air temperature was one hundred plus degrees. Carrying on an exchange with another technician while performing work; I was tasked with servicing the crew oxygen bottle since it was below the minimum value for the service check limit. Referencing M/M 12-15-21 for the servicing limits; I proceeded to the forward pit of the B737-800 to gain access to the O2 panel. As I have done for years; I removed the bottle from the airplane and brought it to the servicing station where it was filled to the specifications as outlined by the manual. After returning to the aircraft with the serviced O2 bottle; I began reinstalling the bottle. During the final steps of the crew O2 bottle installation; I had started a discussion with a fellow technician at the open (cargo) pit door. After fastening the blow-out line and regulator to the bottle; in my mind; I recall opening the valve to the full open position and then; back in a quarter turn; before installing the break-away wire. I don't recall removing my hand from the valve after beginning to open it. I performed the leak check after securing all connections and all checked out good. Our conversation had carried through to completion of the bottle install.As we were walking away from the aircraft; I asked my fellow technician to perform the functional test while I proceeded to the office to address the paperwork. He acknowledged that he would perform the test and I went to the office. I filled out the log page with the appropriate information about the crew O2 reading and the applicable servicing that was accomplished. The functional test was performed and signed by a separate technician and I finished the log page by signing-off the resolution box.
Second reporter narrative
The only external factors that may have impacted the event that I can think of; is maybe the temperatures. The temperatures here at that time of night in August are over 100 Fahrenheit. I was also carrying on a conversation with Mr. X about our furloughs as he was installing the bottle.We were tasked to do a Service Check on a B737-800 aircraft. The only task left was to service the Crew O2 as it was found to be out of service check limits. Mr. X volunteered to service it and I decided to give him a hand and perform the Operational Check. He removed power from the plane and proceeded to remove and service the bottle. As he installed the bottle back in the aircraft; I stood in the baggage door and talked to him. After he completed the installation; he gave me the OK to apply power and do the Operational Check. I then performed the Operational Check as outlined in M/M 12-15-21-601-801-001.The System Operation checked 'good' as described in the task. I was then sitting in the flight deck when Mr. Y walked onto the aircraft and we had a short conversation. After the conversation he asked me if I had performed the O2 Operational Check yet; as he had just passed Mr. X on the way in. I said I had completed it and it passed; but we proceeded to check it again as we talked about the O2 system. The System Operations checked 'good' once again and I went to the office to complete my part of the logbook signoff.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.