What was found
PDIS 997 21-30 0265 01APR23 TLH OPEN U CABIN ALTITUDE WARNING ALERT AT FL280 CABIN ALT AUTO 1 AN 2 FAILED COULD NOT GET CONTROL OF PRESSURIZATION . ***EMERGENCY DECLARED*** INFO 01APR23 04:12 MEM U ********************MOCC UPDATE******************** PLEASE WORK IN CONJUNCTION WITH TSI: 21-30/0264 *************THANKS MOCC TECH SERVICES************* 01APR23 05:00 MEM R OLD DISCREPANCY : 997 / 36-11 / 0000263 REPLACED #2 AUTOMATIC PRESSURE CONTROL UNIT REPLACED CABIN PRESSURE CONTROL PANEL REPLACED #1 AUTOMATIC PRESSURE CONTROL UNIT REPLACED CABIN PRESSURE OUTFLOW VALVE ACTUATOR