As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT CREW REPORTED THE FIRST OFFICERS OXYGEN MASK IS LEAKING. MAINTENANCE REMOVED AND REPLACED THE FIRST OFFICERS OXYGEN MASK IAW T/C R1B35301, OPERATIONAL CHECK WAS GOOD. VENDOR LEAK TEST OF OXYGEN MASK S/N 23208 FOUND NO LEAKS, REASON FOR REMOVAL WAS NOT CONFIRMED. A FULL INSPECTION OF MASK WAS ACCOMPLISHED IN WHICH NUMEROUS DEFECTIVE PARTS WERE REPLACED. THESE ITEMS INCLUDE A FRAYED PNEUMATIC HARNESS (P/N MXH30), 10 EACH O-RINGS (P/N R03460X240A20B6), GASKET SEAL (P/N 553008), AND VISOR (P/N 446268).