ACFT EQUIP PROB DEPRESSURIZATION.

Narrative

WHILE IN CRUISE AT FL330; CABIN ALT HORN AND CABIN ALT WARNING LIGHT CAME ON. THE CABIN HAD CLBED RAPIDLY TO 13000 FT AND WE DECLARED AN EMER AND INITIATED AN EMER DSCNT. CTR CLRED US TO 10000 FT AS WE ACCOMPLISHED THE LOSS OF PRESSURIZATION CHKLIST. THE OUTFLOW VALVE WAS OPEN; SO MANUAL PRESSURIZATION WAS SELECTED AND THE OUTFLOW VALVE SLOWLY STARTED TO CLOSE. WHEN WE LEVELED OFF AT 10000 FT; THE CABIN PRESSURE STABILIZED AT 9000 FT AND WAS CTLED IN THE MANUAL MODE UNTIL LNDG. OTHER THAN THE RAPID DSCNT; NO OTHER PRIORITY HANDLING WAS NECESSARY AND WE CONTINUED ON TO BOSTON WITH NO OTHER PROBS. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: ACFT WAS DISPATCHED WITH 1 AIR CONDITIONING/PRESSURIZATION PACK INOP AND 1 CABIN PRESS CTLR INOP. APPARENTLY; EITHER THE 1 PACK COULDN'T SUPPLY THE PRESSURE DEMAND AT THE ALT OR; A COMBINATION OF THAT; AND THE 1 PRESSURE CTLR MALFUNCTIONED. ACFT BEGAN SLOWLY DEPRESSURIZING UNBEKNOWNST TO THE FLC UNTIL THE CABIN ALT HORN AND WARNING LIGHT CAME ON AT 10000 FT CABIN ALT. THE OUTFLOW VALVE THEN WENT TO FULL OPEN; FLC DONNED OXYGEN MASKS; DECLARED AN EMER AND COMMENCED EMER DSCNT. FO SELECTED MANUAL PRESSURIZATION AND WAS ABLE TO REESTABLISH CTL OF PRESSURIZATION. PAX OXYGEN MASKS DID NOT DEPLOY AND; IN FACT; THE ENTIRE CABIN WAS UNAWARE OF THE PROB. A FLT ATTENDANT CAME TO THE COCKPIT AND SEEING THE FLC WITH DONNED OXYGEN MASKS ASKED; 'IS THERE A PROB?'