What was found
DURING FLIGHT 3667/3409 WHILE DESCENDING FROM 11,000 FT TO 10,000 FT ALL 02 MASKS DROPPED OUT, PRESSURIZATION WAS WORKING NORMAL INDICATING A LANDING OF ABOUT 1,400 FT. OVERRIDE SWITCHES WERE NOT ACTIVATED, NO CABIN HI ALT ANNUNCIATOR WAS INDICATED. MAINTENANCE REMOVED AND REPLACED O2 GENERATOR AND SWITCH, REMOVED AND REPLACED ANEROID SWITCH P/N 101809-02 9824176A, S/N OFF 09218, IAW 35-20-35 AND 02 GENERATOR P/N 9903976, S/N OFF 00616, S/N ON 117028-03, IAW JC 0501, REMOVED FROM DMR MXC NOTIFIED.