What was found
AFTER APPROXIMATELY 30MIN OF FLIGHT WE HEARD A LOUD EXCAPING OF AIR COMING FROM THE COURRIER SECTION. WE NOTICED THAT THE O2 SYSTEM READINGS ON SYSTEM 1 & 3 WERE DECREASING, #2 REMAINED @ 2000 PSI. NO AIR WAS AVAILABLE THROUGH THE OXYGEN MASKS IN THE COURRIER SECTION. SYSTEM READINGS: 1=0 PSI 2= 1700 PSI 3=0PSI. FACT 24SEP19 INSTALLED NEW FLEX LINE IN COURIER AREA ABOVE JUMP SEATS, R&R'D #1 AND #2 O2 BOTTLES AND LEAK CHECKED BOTTLES AND LINE IAW MM 35-11-01-4-0. LEAK CHECK GOOD.