A DC10-10 IMMEDIATELY AFTER TKOF AT 3000 FT DECLARED AN EMER; DUMPED FUEL AND RETURNED TO THE FIELD DUE TO UNABLE TO PRESSURIZE THE ACFT CAUSED BY A FAILED CABIN DOOR SEAL. ACFT LANDED OVERWT.

Narrative

SHORTLY AFTER TKOF WE EXPERIENCED PRESSURIZATION PROBS AND FOUND THE ACFT WAS NOT PRESSURIZING. AT ABOUT 1000 FT THE FLT ATTENDANTS CALLED AND SAID ONE OF THE CABIN DOORS WAS NOT CLOSED TIGHT; THAT IT WAS NOISY; BREEZY AND YOU COULD SEE DAYLIGHT AROUND IT. I INFORMED THE CAPT WE WERE HAVING A PRESSURIZATION PROB AND I NEED SOME TIME TO SEE WHAT I COULD DO. WE LEVELED OFF AND I TRIED DIFFERENT PROCS AND GOT OUT THE CHKLISTS THAT PERTAINED TO OUR PROB. I WAS ALSO CHKING DOOR LIGHTS; ALL THE CIRCUIT BREAKERS AND MANUALLY TRYING TO GET THE OUTFLOW VALVE TO CLOSE; SO THAT THE ACFT WOULD PRESSURIZE. THE CAPT SAID WE WERE RETURNING TO THE ARPT AND TO DUMP FUEL. I SAID ABOUT 1 MIN OF DUMP SHOULD DO AND DUMPED FOR APPROX 1 MIN 40 SECONDS. I TERMINATED DUMPING; COMPLETED THE DSCNT CHKLIST AND THEN THE BEFORE LNDG CHKLIST AS WE WERE ON FINAL APCH. TWICE DURING THE APCH I ADDED UP THE FUEL REMAINING TO MAKE SURE WE WERE AT OR BELOW MAX LNDG WT. WE APPEARED TO BE ALL RIGHT. WE LANDED NICELY AND PROCEEDED TO THE GATE. WE WERE LATER NOTIFIED BY OUR DISPATCH THAT WE HAD LANDED APPROX 3000 LBS OVERWT; ABOUT 366000 LBS. OUR MAX LNDG WT IS 363;500 LBS. I FEEL IF WE HAD JUST HELD OUT THERE AT LEVEL ALT A LITTLE LONGER; AND HAD MORE TIME; WE WOULDN'T HAVE LANDED OVERWT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE CAUSE OF THE PRESSURIZATION FAILURE WAS AN ACFT CABIN ENTRANCE DOOR SEAL THAT WAS DAMAGED AND WOULD NOT SEAL. THE RPTR SAID THE MAINT PEOPLE ADJUSTED OR REPLACED THE SEAL AND THEN REPLACED THE AUTO AND STANDBY PRESSURE CTLRS PRECAUTIONARY.