What was found
ON FLIGHT 3335 THE CREW REPORTED, DURING CRUISE HAD A GRADUAL LOSS OF PRESSURE AND COULD NOT MAINTAIN CABIN ALTITUDE. THE CREW ELECTED TO DIVERT TO SGF. THE AIRCRAFT LANDED WITHOUT INCIDENT. THE AIRCRAFT WAS REMOVED FROM SERVICE. REMOVED AND REPLACED SLEEVE CLAMPS AT NR 1 HEAT EXCHANGER & DUAL TEMPERATURE CONTROL VALVE TUBE NR 1 IAW EMB AMM 21-60-01 & EMB AMM 21-51-02. THE PRESSURE CONTROL SYSTEM TESTS WERE GOOD IAW EMB AMM 21-31-00. THE AIRCRAFT WAS RETURNED TO SERVICE.