ATX SMT ACFT BAGGAGE DOOR OPENED DURING THE TKOF.

Narrative

SHORTLY AFTER BECOMING AIRBORNE ON TKOF FROM RWY 18 AT CHICAGO MEIGS; THE NOSE COMPARTMENT BAGGAGE DOOR CAME OPEN. FLT WAS CONTINUED AROUND THE TFC PATTERN TO A LNDG BACK ON RWY 18. IT IS SUSPECTED THAT THE LATCHES (THERE ARE 2) WERE SECURED; BUT THE BAGGAGE DOOR HAD NOT BEEN LOCKED. A MORE THOROUGH PREFLT INCLUDING THE LOCKING OF THE BAGGAGE DOOR WOULD HAVE PREVENTED THE OCCURRENCE. IT SHOULD BE NOTED THAT THE POH DOES NOT SPECIFY TO LOCK THE BAGGAGE DOOR TO SECURE IT; ALTHOUGH MOST OPERATORS OF THE TWINS RECOMMEND TO DO SO. SUPPLEMENTAL INFO FROM ACN 206859: AFTER PERFORMING THE WALK AROUND INSPECTION MYSELF; WE LOADED OUR PAX AND TAXIED TO RWY 18 AT CGX. IT WAS MY LEG TO FLY AND 2 SECONDS AFTER LIFTOFF THE L NOSE BAGGAGE DOOR POPPED OPEN AND REMAINED WITH THE ACFT. AFTER DETERMINING THAT THERE WAS NOT SUFFICIENT RWY REMAINING TO LAND ON; WE RETRACTED THE GEAR AND PERFORMED THE AFTER TKOF CHKLIST; THEN REQUESTED IMMEDIATE RETURN FOR LNDG AND WAS GRANTED SUCH. THE CAPT THEN TOOK OVER THE ACFT AND PERFORMED A L TFC PATTERN FOR RWY 18 AT CGX. THE BEFORE LNDG CHKLIST WAS CALLED FOR AND ACCOMPLISHED PRIOR TO TURNING FINAL. AFTER LNDG THE DOOR WAS RE- SECURED AFTER BEING INSPECTED BY MYSELF AND THE CAPT; AND FOUND TO HAVE NO DAMAGE; AND THE FLT WAS CONTINUED TO GRR WITHOUT INCIDENT.