What was found
PASSING FLIGHT LEVEL 290 CABIN ALTITUDE EICAS WARNING ILLUMINATED. EMERGENCY DECLARED AT ATB KMEM. FOUND RIGHT PACK CHECK VALVE ORANGE FLEX RUBBER CONNECTION DUCT OFF CK VALVE. RECONNECTED ORANGE DUCT WITH NEW CLAMPS. RAN THE APU ,PRESSURIZED A/C WITH RIGHT PACK ONLY TO 4.0 PSID. DIFFERENTIAL AND RATE INDICATOR NEEDLE WERE STEADY. PRESSURE DECAY TIMES WERE FROM 4 PSID TO 3 PSID 2:15 MINS, 4 TO 2 4:40, 4 TO 1 6:45, 4 TO 1 8 MINS. RIGHT OPS AND LEAK CHECKS SAT. REF AMM CHPT 21-51-00-5 & 05-51-24-2. A/C OK FOR SERVICE.