What was found
CREW OXYGEN LOW ADVISORY CREW OXYGEN PRESSURE IS LOW. POSSIBLE CAUSES ARE; CREW OXYGEN US AGE, LEAKAGE IN TUBING, OR CYLINDER SHUTOFF VALVE IS CLOSED. O2 IN COCKPIT READS 0. INSPECTED CREW O2 BOTTLE, #1 BOTTLE INDICATED ZERO PSI. #2 BOTTLE WAS AT 1500 PSI. OVERBOARD DISCHARGE DISK APPEARS TO REMAIN INTACT. INSPECTED #1 CREW O2 BOTTLE, ALL LINES ARE TIGHT. REMOVED AND REPLACED #1 CREW O2 BOTTLE REF. DMC-B787-A-12-15-08-00B-200A-A. LEAK CHECKED ALL LINES, FOUND NO LEAKS. TESTED O2 IN FLIGHT DECK FROM ALL MASKS, O2 FLOWS FREELY AND DOESNT DROP. ENSURED PSI DIDNT CHANGE FOR 2 HRS. OK FOR CONTINUED USE.