What was found
AT CRUISE FL340, AIR PACK 1 AND 2 FAULT ECAM MESSAGE APPEARED. PROCEDURE TO TURN #1 PACK OFF, DID NOT DO THIS SINCE #2 PACK WAS INOPERABLE. DECLARED AN EMERGENCY AND EXECUTED RAPID DESCENT MANEUVER. DID NOT LOSE CABIN PRESSURE, LEVELED OFF AT 10,000 FEET. LANDED WITHOUT FURTHER ISSUES. MAINTENANCE REPLACED RIGHT HAND FLOW CONTROL VALVE PER AMM 21-51-51 AND ACCOMPLISHED SATISFACTORY OPERATIONAL CHECK PER AMM 21-51-00. AIRCRAFT WAS GROUNDED.