What was found
(CAN) AIRCRAFT AT 28,000 FT HAD LOSS OF CABIN PRESSURE CONTROL. AIRCRAFT EXECUTED EMERGENCY DESCENT TO 10,000 FT PROCEEDING TO DESTINATION WITHOUT FURTHER INCIDENT. MAINTENANCE INVESTIGATION REVEALED ACM FLEX DUCT HAD UNCOUPLED FROM MATING TUBE, SUSPECTED CAUSE OF THE DECOUPLING WAS A LOOSE GEAR CLAMP.