LR45 SUFFERS LOSS OF CABIN PRESSURIZATION. MAKES EMERGENCY DESCENT AND DIVERTS.

Narrative

DURING CRUISE FLT; THE CREW WAS ALERTED BY THE MASTER CAUTION; CHIME; AND AMBER CABIN ALT CAS MESSAGE THAT INDICATED THAT THE ACFT HAD A PRESSURIZATION PROB. THIS WAS CONFIRMED BY OBSERVING AN INCREASE IN CABIN ALT ON THE PRESSURIZATION PANEL. AT THIS POINT THE PF ADVISED THE PNF TO ALSO DON HIS MASK. WHILE THE PF MONITORED CABIN PRESSURE; THE PNF BEGAN EXECUTING THE CABIN ALT CHKLIST. PF MONITORED CABIN PRESSURE ALT; WHICH CONTINUED TO CLB AND ADVISED PNF TO REQUEST LOWER ALT. AFTER INITIALLY EXECUTING A NORMAL DSCNT; THE CABIN PRESSURE BEGAN TO RAPIDLY INCREASE; AT WHICH TIME THE DECISION TO INITIATE AN EMER DSCNT WAS MADE. ATC WAS ADVISED THAT WE HAD INITIATED EMER DSCNT AND WE REQUESTED ALTERNATE LNDG INSTRUCTIONS. ATC ADVISED US THAT ZZZ WOULD BE A GOOD ALTERNATE FOR OUR CONDITION AND ALSO ADVISED US; IF ABLE; TO TURN 20 DEGS R FOR TFC; WHICH WE WERE ABLE TO COMPLY WITH. WE MADE A DECISION TO GO AHEAD AND DIVERT TO ZZZ AS ADVISED BY ATC. AFTER LEVELING AT 10000 FT; ATC GAVE US INSTRUCTION TO TURN TO A HDG OF 070 DEGS DIRECT TO ZZZ; WHICH WE COMPLIED WITH. DURING PREPARATION FOR LNDG; WE THEN RECEIVED A CAS MESSAGE INDICATING A CAB DUCT OVERHEAT; AT WHICH POINT THE PNF STARTED EXECUTING THE CAB DUCT OVERHEAT CHKLIST WHILE THE PF REQUESTED ATC TO DIRECT US TO THE NEAREST ARPT WITH A 6000+ FT RWY AND DECLARED AN EMER. AFTER COMPLETING THE CHKLIST; THE PNF ADVISED THE PF THAT THE PROB HAD BEEN RESOLVED; AT WHICH TIME WE REQUESTED CONTINUING ON TO ZZZ. AT THIS TIME; THE ENTIRE EMER CHKLIST HAD BEEN EXECUTED AND COMPLETED. WE THEN COMPLETED A NORMAL LNDG WITHOUT INCIDENT OR INJURY TO CREW AND PAX. WE EXITED THE ACTIVE AND REQUESTED TAXI INSTRUCTIONS TO THE NEAREST FBO. PNF REMOVED PAX FROM THE ACFT AND ESCORTED THEM TO THE FBO LOBBY WHILE THE PF SECURED THE ACFT. PNF ADVISED EMT PERSONNEL TO COME IN AND GIVE ASSISTANCE TO THE PAX IF IT BECAME NECESSARY.