What was found
AT FL70 CABIN ALT WARNING HORN SOUNDED, CHECKED CABIN ALT GOING ABOVE 10,000. DID AN EMERGENCY DESCENT AND RAN CHECKLIST WAS NOT ABLE TO CONTROL CABIN IN MANUAL UNTIL BELOW 10,000 T/S PER AMM 21-31-25 FAULT CODE 030. PERFORMED HEALTH CHECK REF AMM 21-30-00/601, TEST PASSED. REMOVED AND REPLACED O/H CONTROL MODULE PRECAUTIONARY PER AMM 21-31-25, CHECK OK. BITE & PRESS CHECKED AGAIN PRECAUTIONARY CHECK OK. PANEL, PRESS, C OFF 24-2131-9-0001 2845 ON 24-2131-9-0001 2019.