C421 PLT REJECTED TKOF WHEN A CARGO DOOR OPENED DURING TKOF ROLL.

Narrative

I HAD COMPLETED A CHARTER FLT; AND STOPPED IN FRONT OF THE LANAI TERMINAL BUILDING TO DEPLANE MY 2 PAX. I WAS UNLOADING THE LUGGAGE FROM FRONT BAGGAGE COMPARTMENT; WHEN A GUARD APCHED ME AND TOLD ME TO MOVE MY AIRPLANE TO TRANSIENT PARKING IMMEDIATELY. HE ALLOWED ME TO ESCORT MY PAX WITH LUGGAGE TO RAMP GATE. I DECIDED I SHOULD QUICKLY REPOS THE ACFT TO THE S RAMP AND HURRIED BACK TO THE AIRPLANE. THE GAS CARTRIDGE WHICH HOLDS THE CARGO DOOR IN THE UPRIGHT/OPEN POS DID NOT SUCCEED IN THE WIND; AND THE DOOR APPEARED SHUT AS I RETURNED TO THE AIRPLANE. I FORGOT THAT I HAD NOT LATCHED THE DOOR AND LOCKED IT WITH THE KEY. TYPICALLY; THE DOOR WOULD BE UPRIGHT (OPEN) AND WOULD PRESENT ITSELF AS AN OBVIOUS CLUE THAT THE DOOR WAS NOT SECURE. I MOVED THE ACFT; AND THEN DECIDED TO GET MY IFR CLRNC WHILE THE ENGS WERE RUNNING. UPON RECEIVING THE CLRNC FROM HFC APCH; I RECEIVED A VOID TIME OF 10 MINS LATER. AT THIS POINT; I FORGOT MY RESOLVE TO DO A PERFUNCTORY WALKAROUND PRIOR TO TKOF. I TAXIED TO THE DEP END OF THE RWY; THINKING ALL WAS WELL. MY BEFORE TKOF CHKLIST COMPLETE; I COMMENCED THE TKOF ROLL FROM THE UNCTLED AIRFIELD. THE RWY IS PAVED; 5000 FT LONG. IT IS A GOOD ARPT RWY. AT APPROX 65 KTS; THE CARGO DOOR POPPED OPEN TO THE FULLY EXTENDED POS. I ABORTED THE TKOF IMMEDIATELY; AND BRAKED TO AN UNEVENTFUL STOP. I CLRED THE ACTIVE RWY; AND ADVISED CTR THAT MY DEP WOULD BE DELAYED. I SHUT THE ENGS DOWN; AND DID A CAREFUL INSPECTION OF THE WHEELS/BRAKES. THE BRAKES WERE HOT; BUT NOT SMOKING. THERE WAS NO SIGN OF ABNORMAL CONDITIONS I ELECTED TO ALLOW THE BRAKES TO COOL FOR 20 MINS; TO PRECLUDE ANY PROBS IN STOPPING THE ACFT IF I HAD TO ABORT FOR ANY REASON ON THE SECOND TKOF ATTEMPT. I HAD A PERSONAL TALK WITH MYSELF AS I WAITED. I THEN OBTAINED MY TKOF CLRNC FROM CTR; AND DEPARTED. I KNOW IT IS ESSENTIAL TO CHK ALL DOORS PRIOR TO TKOF. THE FAULTY DOOR STRUT AND THE PARKING HASSLE SET UP AN ERROR CHAIN; AND I FELL VICTIM TO COMPROMISING MY HIGH STANDARDS. LUCKILY; NO BAGGAGE WAS IN THE NOSE; AND THE EVENT LED TO NO MISHAP. PLTS MUST BE VIGILANT TO DO A GOOD PREFLT!