What was found
FLIGHT CREW REPORTS THEY ARE SUSPECT OF AN OXYGEN LEAK AFTER O2 QUANTITY DROPPED TO 76% AFTER BEING SERVICED. THE MAINTENANCE TEAM TROUBLESHOT AND DETERMINED THAT THE PILOTS SIDE AND 3RD CREW MEMBER EMERGENCY OXYGEN MASKS WERE LEAKING. THE PILOTS SIDE MASK P/N MC10-12-151 S/N 5232 WAS OVERHAULED DEC2019 AND THE 3RD CREW MEMBER MASK P/N MC10-12-151 S/N 87101 WAS OVERHAULED FEB2019. BOTH MASKS HAVE A 6 YEAR OVERHAUL PERIOD. BOTH MASKS WERE REPLACED WITH OVERHAULED UNITS AND THE AIRCRAFT WAS RETURN TO SERVICE.