Narrative:

Therapeutic O2 was removed from aircraft seat. When mechanic removed bottle; we found the regulator turned down but the fill valve open and the O2 mask attached to bottle. Passenger had got off the airplane in ZZZ1 and so that bottle was on for 2.5 hours; dumping O2 into overhead bin!! Supplemental information from acn 667732: our aircraft was carrying a company-installed oxygen bottle for a passenger to use on the flight previous to ours. There is no company maintenance in the departure station; and the oxygen bottle was to remain aboard until removed by maintenance at our next stop. The departure station personnel un-taped the oxygen hose from the cabin sidewall; rolled it up; and secured it to the top of the oxygen bottle in the overhead. After we had parked and deplaned at the gate; the mechanic who removed the oxygen bottle advised us that he had found the valve on top of the bottle rotated to the full open ('on') position. There is no provision in the pilot operating procedures to examine a company-installed oxygen bottle to confirm that the flow valve and regulator are both selected full closed ('off') if the bottle is not used on that flight. I do not know what procedures are in the flight attendant's manual relating to this situation. Since free flowing pure oxygen entering the pressurized structure would support combustion in the presence of a source of ignition; and since we fly through many non-maintenance stations; perhaps we should institute such a safety check by either the pilots or flight attendants.

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Original NASA ASRS Text

Title: AN A320 HAD A PAX ON THERAPEUTIC O2. PAX DEPLANED AND ACFT DEPARTED FOR 2.5 HR FLT. O2 BOTTLE FILL VALVE WAS OPEN AND OXYGEN FILLED OVERHEAD BIN.

Narrative: THERAPEUTIC O2 WAS REMOVED FROM ACFT SEAT. WHEN MECHANIC REMOVED BOTTLE; WE FOUND THE REGULATOR TURNED DOWN BUT THE FILL VALVE OPEN AND THE O2 MASK ATTACHED TO BOTTLE. PAX HAD GOT OFF THE AIRPLANE IN ZZZ1 AND SO THAT BOTTLE WAS ON FOR 2.5 HRS; DUMPING O2 INTO OVERHEAD BIN!! SUPPLEMENTAL INFO FROM ACN 667732: OUR ACFT WAS CARRYING A COMPANY-INSTALLED OXYGEN BOTTLE FOR A PAX TO USE ON THE FLT PREVIOUS TO OURS. THERE IS NO COMPANY MAINT IN THE DEP STATION; AND THE OXYGEN BOTTLE WAS TO REMAIN ABOARD UNTIL REMOVED BY MAINT AT OUR NEXT STOP. THE DEP STATION PERSONNEL UN-TAPED THE OXYGEN HOSE FROM THE CABIN SIDEWALL; ROLLED IT UP; AND SECURED IT TO THE TOP OF THE OXYGEN BOTTLE IN THE OVERHEAD. AFTER WE HAD PARKED AND DEPLANED AT THE GATE; THE MECH WHO REMOVED THE OXYGEN BOTTLE ADVISED US THAT HE HAD FOUND THE VALVE ON TOP OF THE BOTTLE ROTATED TO THE FULL OPEN ('ON') POS. THERE IS NO PROVISION IN THE PLT OPERATING PROCS TO EXAMINE A COMPANY-INSTALLED OXYGEN BOTTLE TO CONFIRM THAT THE FLOW VALVE AND REGULATOR ARE BOTH SELECTED FULL CLOSED ('OFF') IF THE BOTTLE IS NOT USED ON THAT FLT. I DO NOT KNOW WHAT PROCS ARE IN THE FLT ATTENDANT'S MANUAL RELATING TO THIS SIT. SINCE FREE FLOWING PURE OXYGEN ENTERING THE PRESSURIZED STRUCTURE WOULD SUPPORT COMBUSTION IN THE PRESENCE OF A SOURCE OF IGNITION; AND SINCE WE FLY THROUGH MANY NON-MAINT STATIONS; PERHAPS WE SHOULD INSTITUTE SUCH A SAFETY CHK BY EITHER THE PLTS OR FLT ATTENDANTS.

Data retrieved from NASA's ASRS site as of January 2009 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.