What was found
LEFT PACK UNABLE TO MAINTAIN CABIN ALTITUDE BELOW 10000FT AT FL330 LOCKED DUE TO CREW DECLARED EMERGENCY. DURING PRESSURIZATION CHECKS NOTICED THAT THE CABIN AIR SUPPLY CHECK VALVE AFT BOOT HAD MISSING BAND CLAMP. INSTALLED NEW BAND CLAMP AND PERFORMED LEAK CHECKS. NO LEAKS FOUND. REF AMM 21-51-15-404-011. PERFORMED EXCESSIVE CABIN PRESSURE LEAKAGE TEST WITH LH PACK REFERENCING AMM 05-51-24-702-001. ABLE TO MAINTAIN CABIN PRESSURE FOR SEVERAL MINUTES.