What was found
PAR/BOG - FLT 015 - AUTO INOP LIGHT ILLUMINATED. EICAS MESSAGE, CABIN AUTO INOP AND CABIN ALT AUTO 1 AND DISPLAYED. OPERATION IN MANUAL MODE WAS OK. CABIN ALTITUDE WARNING AND MESSAGE CAME ON. OXYGEN MASKS WERE DROPPED BY PILOTS. PERFORMED BITE PROCEDURE IAW FIM 21-30-00, PAGE 109. OUTFLOW VALVE CHANGED. CYCLES, 4,953. HOURS, 23,854.