MU2B PLT HAS HATCH BLOW OFF IN FLT.

Narrative

I DEPARTED TULSA INTL IN WHICH I WAS FLYING A FREIGHT HAUL IN A MITSUBISHI MU2B. IN THESE AIRPLANES; THEY HAVE AN EMER HATCH WHICH IS A CONVERSION ON THE PLT SIDE WINDOW OR COPLT SIDE. THIS PARTICULAR CONVERSION WAS INSTALLED ON THE COPLT'S SIDE WINDOW. AFTER RUNNING ALL OF MY CHKLISTS AND CHKING THIS WINDOW SEVERAL TIMES; I LINED UP FOR TKOF. I DEPARTED ON RWY 36R IN WHICH I TURNED TO A HDG OF 060 DEGS AND 2500 FT. I SWITCHED TO DEP AND WAS CLRED ON COURSE TO 1FO AND UP TO 16000 FT. GOING THROUGH 6000-7000 FT THE EMER HATCH DEPARTED THE ACFT. I THEN DECLARED AN EMER AND RECEIVED VECTORS AND A DSCNT BACK TO TUL INTL. THE CEILING WAS AT 1600 FT; SO I WAS GIVEN AN ASR APCH. THIS WAS FILED WITH THE FAA AS AN ACFT INCIDENT. THE ONLY DAMAGE WAS A COM ANTENNA WHICH WAS SHATTERED ON TOP OF COCKPIT AND A PUNCTURE ON THE AFT R SIDE OF THE ACFT. I FEEL THAT THIS SPECIFIC CONVERSION HAD MANY FLAWS IN IT AND SHOULD HAVE RECEIVED AN AIRWORTHINESS DIRECTIVE TO CHK THE LATCHING MECHANISM AND PINS. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATES THAT ALL FAA RPTS AND INSPECTIONS WERE COMPLETED. THE ACFT HAS BEEN REPAIRED AND IS BACK IN SVC. CONVERSION IS OLD. THIS CONVERSION IS ONE OF THREE MADE AND THE NEWER CONVERSIONS ARE DIFFERENT. THEY HAVE 7 LOCKING PINS; THE OLD ONES HAD LESS. RPTR IS TRYING TO CONTACT THE MECH WHO DOES THESE CONVERSIONS FOR THE COMPANY BUT HAS BEEN UNABLE TO AND CANNOT OFFER FURTHER INFO. THE ANTENNA DAMAGE CAUSED A LOSS OF COM INITIALLY; THE HATCH THEN FLEW OFF THE ROOF AND CUT A HOLE IN THE R SIDE OF THE ACFT.