CL65 CREW MADE A RAPID DSCNT TO 10000 FT AFTER THEY WERE DEFERRED WITH THE L PACK MEL'ED INOP AND THE R PACK TRIPPED OFF.

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DURING CLBOUT FROM FL180 TO FL190; RECEIVED A 'CABIN ALT' CAUTION MESSAGE. AFTER THIS OCCURRED; WE REQUESTED AN IMMEDIATE DSCNT TO 10000 FT FROM ATC. ATC ADVISED US THAT THIS WAS APPROVED AND CLRED US TO 10000 FT. WITHIN SECONDS OF BEGINNING DSCNT; WE RECEIVED A 'CABIN ALT' WARNING MESSAGE WITH A 'CABIN PRESSURE' AURAL MESSAGE. MY FO AND I EXECUTED MEMORY ITEMS AND APPROPRIATE QRH PROCS. AFTER STABILIZING AT 10000 FT AND COMPLETING ALL CHKLISTS; WE USED THIS TIME TO TALK TO THE FLT ATTENDANT. SHE NOTIFIED US THAT ALL PAX WERE FINE AND NEVER NOTICED ANYTHING UNUSUAL. SHE ALSO STATED THAT SHE WAS FINE AND NOTICED NOTHING UNUSUAL AS WELL. SINCE NO STRUCTURAL DAMAGE WAS SUSPECTED; WE OPTED NOT TO DECLARE AN EMER. WE WERE APPROX 20 MINS OUTSIDE CVG; WE OPTED TO CONTINUE TO CVG. SINCE ALL PAX RPTED NO PROBS; WE OPTED NOT TO DEPLOY MASKS IN ORDER NOT TO FRIGHTEN THE PAX. WE NEVER EXCEEDED 12000 FT CABIN ALT EVEN AT OUR HIGHEST ALT OF FL180. WHEN LEVEL AT 10000 FT; WE ATTEMPTED TO RESET OUR R PACK (ACM) WHICH HAD FALLEN OFF-LINE. OUR L PACK (ACM) WAS DEFERRED AT THE TIME PER MAINT CTL. THE R PACK WOULD NOT RESET. MAINT WAS NOTIFIED ENRTE. THE PAX WERE SPOKEN TO TWICE ABOUT OUR SIT. WE LANDED WITH NO FURTHER OCCURRENCE.