A WDB ACR CREW HAD A BLOWN AIR CONDITIONING DUCT. THEY LANDED AT AN ENRTE ARPT.

Narrative

ON THE CLBOUT PASSING THROUGH FL280 A THUMP WAS HEARD FOLLOWED BY AN EICAS MESSAGE 'CABIN AUTO INOP.' SHORTLY THEREAFTER; #1 FLT ATTENDANT RPTED THAT A DOOR IN THE REAR WAS LOOSE. CAPT REQUESTED FROM THE CTR A VECTOR AND DSCNT FOR DFW. SEVERAL SECONDS LATER; #1 FLT ATTENDANT RPTED SMOKE IN THE REAR OF THE CABIN AND EICAS MESSAGE 'BODY DUCT LEAK' APPEARED. THE CAPT INSTRUCTED ME TO GO THROUGH THE CHKLIST AND TOLD CTR THAT WE MUST DSND NOW AND LAND AT ABI. A LNDG WAS ACCOMPLISHED AT ABI WITHOUT FURTHER INCIDENT. CLOSING THE CTR DUCT ISOLATION VALVE AS REQUIRED BY THE EMER CHKLIST STOPPED THE HEAT/SMOKE IN THE REAR OF THE CABIN. THE DOOR WAS SECURED; SMOKE AND HOT AIR IN THE REAR OF THE CABIN MUST HAVE GIVEN THE ILLUSION OF THE DOOR MOVING. MAINT INSPECTION REVEALED THAT THE CTR BLEED DUCT LOCATED AFT OF THE REAR BULK CARGO BIN NEAR STATION 1500 HAD SEVERED. ON DEBRIEFING THE EVENTS OF THE FLT WITH THE CAPT; WE WERE NOT CERTAIN THAT WE HAD A CLRNC FROM CTR TO LEAVE OUR ALT. WE AGREED THAT WE SHOULD HAVE DECLARED AN EMER AND HAD CTR CLR US DOWN.