PLT OF AN EMS SMT TWIN ENG ACFT LOST MAIN CABIN DOOR INFLT AND RETURNED TO LAND.

Narrative

DURING AN AIR AMBULANCE FLT FROM HNL TO KOA ON AUG/SAT/93 AT XA30 LCL AND CLBING THROUGH 8000 FT MSL; THE CABIN 'DOOR WARN' LIGHT CAME ON. AFTER LEVELING OFF AT 9000 FT MSL; I INSTRUCTED THE MEDIC ON BOARD TO GO TO THE BACK OF THE ACFT AND PUT HIS SEAT BELT ON AND THEN CHK TO SEE IF THE DOOR WAS PROPERLY CLOSED. IT WAS APPARENTLY NOT FULLY CLOSED. AS HE GRABBED THE HANDLE TO SECURE IT; THE DOOR BLEW OPEN AND SEPARATED FROM THE ACFT. UPON SEPARATION; THE DOOR HIT THE VERT STABILIZER APPROX 1 FT FROM THE TOP. THE ONLY DAMAGE TO THE TAIL WAS APPROX 3 SQUARE INCHES OF PAINT MISSING FROM THE L FRONT PORTION OF THE TAIL. WHEN THE DOOR BLEW OFF; THERE WAS AN EXPLOSIVE DECOMPRESSION IN THE CABIN AND AN ACCOMPANYING LOUD RUSH OF AIR. I INSTRUCTED THE 2 MEDICS ABOARD TO REMAIN CALM WITH THEIR SEAT BELTS ON AND THAT WE WOULD BE RETURNING TO LAND IN HNL. DURING THE DSCNT AND RETURN TO HNL; I KEPT THE ACFT BELOW 160 KTS BECAUSE I WAS UNSURE IF THE ACFT WAS STRUCTURALLY DAMAGED. HOWEVER; I DID NOT FEEL ANY UNUSUAL VIBRATIONS OR EXPERIENCE ANY PROBS WITH THE FLT CTLS. THE DSCNT AND RETURN FOR LNDG IN HNL WERE UNEVENTFUL. I BELIEVE THE PROB ORIGINATED WITH THE MEDIC NOT PROPERLY SECURING THE DOOR PRIOR TO TKOF. ALTHOUGH I WATCHED HIM CLOSE THE DOOR AND CHKED THE ANNUNCIATOR PANEL TO ENSURE THE 'DOOR WARN' LIGHT WAS OUT PRIOR TO TKOF; I BELIEVE THE LATCH IN THE UPPER PORTION OF THE DOOR WAS NOT FULLY LATCHED TO THE BOTTOM DOOR. I DID NOT DEPRESSURIZE THE CABIN PRIOR TO ASKING THE MEDIC TO CHK THE LATCH; AS I THOUGHT CHANGING THE PRESSURE FORCES ON THE DOOR MAY HAVE CAUSED IT TO OPEN ANYWAY. TO PREVENT ANY FUTURE OCCURRENCE OF THIS; I WILL PERSONALLY CLOSE AND INSPECT THE DOOR LATCH AND PINS PRIOR TO ENG STARTUP. I WILL NO LONGER TRUST THE MEDICS TO SHUT THE DOOR EVEN THOUGH THEY HAVE BEEN TRAINED HOW TO CLOSE AND INSPECT THE DOOR TO ENSURE IT IS PROPERLY CLOSED. WHILE I FEEL THE 2 MEDICS ON BOARD WITH ME DURING THIS FLT NOW UNDERSTAND THE IMPORTANCE OF ENSURING THAT THE LATCH AND PINS ARE SECURE; I DO NOT BELIEVE THAT THE OTHER MEDICS THAT WORK FOR THE COMPANY DO. I WILL ALSO ADVISE THE CHIEF PLT AND DIRECTOR OF OPS THAT I BELIEVE THE COMPANY SHOULD SET A PROC THAT ONLY THE PLTS SHOULD SHUT THE DOOR OF THE ACFT.