PLT OF C208 RETURNS TO DEP ARPT AFTER LEARNING CARGO POD DOOR HAD OPENED PRIOR TO TKOF.

Narrative

I PICKED UP THE ACFT AT THE MAINT HANGAR FOR THE FERRY FLT. WHILE WAITING FOR THE ACFT PAPERWORK TO BE COMPLETED; I PREFLTED THE ACFT; PHYSICALLY CHKING THE SECURITY OF THE CARGO AND POD DOORS AS PART OF MY INSPECTION. AFTER FUELING ON THE RAMP AND PRIOR TO ENG START; I VISUALLY CHKED THE ACFT OVER; VERIFYING CARGO AND POD DOORS CLOSED; TAIL STAND REMOVED AND CHOCKS REMOVED AND STOWED. AFTER RECEIVING CLRNC; I TAXIED TO THE RAMP BOUNDARY; DID MY PRE-TKOF CHKS AND RUN-UP; THEN TAXIED TO AND DEPARTED. UPON CHKING IN WITH DEP; I WAS INFORMED BY ATC THE COMPANY MAINT PERSONNEL HAD RPTED THAT A POD DOOR MIGHT HAVE OPENED DURING MY RUN-UP. I ARRANGED WITH ATC FOR A FLY-BY SO THAT THE TWR CTLR COULD VISUALLY VERIFY AN OPEN POD DOOR. THE TWR CONFIRMED THAT A POD DOOR APPEARED TO BE OPEN AND CLRED ME FOR A LNDG. THE LNDG WAS UNEVENTFUL AND AFTER REACHING THE RAMP I SHUT DOWN AND SECURED THE ACFT FOR INSPECTION. I FOUND POD DOOR 'C' OPEN AND UNDAMAGED. I CLOSED THE DOOR AGAIN; NOTING ONLY THAT THE DOOR LATCHES APPEARED TO BE STIFFER IN OP THAN NORMAL. AFTER RECEIVING CLRNC AGAIN; I STARTED THE ACFT'S ENG AND PROCEEDED TO RWY FOR AN UNEVENTFUL TKOF AND FLT TO THE DEST ARPT. UPON LNDG AT THE DEST; I NOTED THAT ALL POD DOORS WERE STILL CLOSED AND SECURE. DURING THE INCIDENT NO EMER WAS DECLARED AND THE ACFT DID NOT PRESENT ANY HAZARD TO ANY OTHER ACFT OR THE ARPT FACILITIES. POSTFLT DISCUSSION WITH MAINT REVEALED THAT A MECH HAD OBSERVED THE POD DOOR OPEN DURING MY PRE-TAXI RUN-UP AND SYS CHK. USING A COMPANY VEHICLE HE HAD BEEN UNABLE TO ALERT ME PRIOR TO MY ENTERING THE TXWY FOR RWY AND HAD CALLED THE TWR AS A LAST RESORT IN ORDER TO NOTIFY OF THE OPEN POD DOOR. MY ONLY CONCLUSION IS THAT THE POD DOOR WAS EITHER NOT FULLY CLOSED OR THE LATCHES WERE NOT COMPLETELY ENGAGED AND THAT THE VIBRATION FROM MY TAXI AND RUN-UP CAUSED THE LATCHES TO RELEASE AND THE POD DOOR TO OPEN. I PLAN TO BE EVEN MORE CAREFUL CHKING THEM FROM NOW ON.