What was found
DURING CRUISE, CABIN ALT ALERT WARNING HORN SOUNDED, CABIN PRESS CLIMBED. CREW INITIATED AN EMERG DESCENT. AT LOWER ALT, WAS ABLE TO GAIN CONTROL OF CABIN ALT. NO EMERG DECLARED. FLT DIVERTED, LANDED W/O INCIDENT. MX ACCOMP A/C PRESS T/S CARD J321-30-00. R/R`D CABIN ALT DIFFERENTIAL PRESS IND, CABIN PRESS CONTROLLER, LEFT RAM AIR TEMP CONTROLLER, LEFT TURBOFAN VALVE AND REPAIRED A SKIN CRACK. HOWEVER, ON 5/4/06 A/C EXPERIENCED A REPEAT EVENT WHEREAS CABIN ALT ALERT WARNING HORN SOUNDED. CREW GAINED CONTROL OF CABIN AS SYS WORKED FINE IN STANDBY. FLT CONTINUED W/O FURTHER INCIDENT. MX R/R`D AFT OUTFLOW VLV AND FOUND BOTH SAFETY RELIEF VALVES BAD. REPLACED BOTH SAFETY RELIEF VLVS. OP CHK OF VLVS GOOD.