Narrative:

Level flight at 17000 ft. Crew only on board. Heard a loud 'kapow' then the aircraft depressurized. As I grabbed for my oxygen mask; the captain began an emergency descent. I called ATC; declared an emergency; told them of our situation and that we were descending to 10000 ft. I'm not sure if the captain descended before the emergency was declared. There was no traffic noted on our traffic avoidance equipment. The cabin door was unlocked (evidenced by yellow caution light). We landed at ZZZ without incident. After landing; we discovered that the door was locked; but the aft upper side latch pin had broken at the threads from the actuating rod. Any unauthorized altitude excursion would have occurred from the captain disengaging the autoplt and descending before the emergency was declared. We are a new crew. More training and better coordination will help prevent any situations like this in the future.

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Original NASA ASRS Text

Title: BE200 FLT CREW EXPERIENCES RAPID DECOMPRESSION AT 17000 FEET AND EXECUTES EMERGENCY DESCENT TO 10000 FEET.

Narrative: LEVEL FLT AT 17000 FT. CREW ONLY ON BOARD. HEARD A LOUD 'KAPOW' THEN THE ACFT DEPRESSURIZED. AS I GRABBED FOR MY OXYGEN MASK; THE CAPT BEGAN AN EMER DSCNT. I CALLED ATC; DECLARED AN EMER; TOLD THEM OF OUR SITUATION AND THAT WE WERE DSNDING TO 10000 FT. I'M NOT SURE IF THE CAPT DSNDED BEFORE THE EMER WAS DECLARED. THERE WAS NO TFC NOTED ON OUR TFC AVOIDANCE EQUIP. THE CABIN DOOR WAS UNLOCKED (EVIDENCED BY YELLOW CAUTION LIGHT). WE LANDED AT ZZZ WITHOUT INCIDENT. AFTER LNDG; WE DISCOVERED THAT THE DOOR WAS LOCKED; BUT THE AFT UPPER SIDE LATCH PIN HAD BROKEN AT THE THREADS FROM THE ACTUATING ROD. ANY UNAUTH ALT EXCURSION WOULD HAVE OCCURRED FROM THE CAPT DISENGAGING THE AUTOPLT AND DSNDING BEFORE THE EMER WAS DECLARED. WE ARE A NEW CREW. MORE TRAINING AND BETTER COORD WILL HELP PREVENT ANY SITUATIONS LIKE THIS IN THE FUTURE.

Data retrieved from NASA's ASRS site as of January 2009 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.