What was found
UNABLE TO MAINTAIN CABIN PRESSURE. CAPTAIN DECLARED AN EMERGENCY WITH ATC, RAN QRH FOR EMERGENCY DESCENT. CHECKED THE OUTFLOW VALVE, CPC, NR 1 & 2 PACK CONTROLLERS, NR 1 & 2 AND ZONE CONTROLLER. NO DEFECTS NOTED. INSPECTED PACK BAYS. FOUND DISCONNECTED DUCT BETWEEN THE RT A/C PACK CONDENSER AND DUCTING TOWARD MIXER. SECURED THE DUCT & CLAMP IAW AMM 21. PRESSURIZED ACFT USING BOTH ENGINES AT IDLE AND APU BLEED. NO DEFECTS NOTED.