SMT CREW DOOR OPENED INFLT.

Narrative

I DEPARTED CLT RWY 36R DURING A RAIN SHOWER. TWR TOLD ME TO FLY 090 DEG HDG AFTER TKOF. AT ABOUT 200 FT AGL THE CABIN DOOR POPPED OPEN (WAS LATER DETERMINED TO BE BROKEN). I ENTERED THE CLOUDS AT ABOUT THE SAME TIME. THE PERFORMANCE OF THE AIRPLANE WAS SEVERELY DEGRADED. I WAS AT VYSE CLBING AT ONLY A COUPLE HUNDRED FPM. I WAS NOT IN A POS (SAFE SPD AND ALT) TO MANEUVER THE AIRPLANE; SO I INTENDED TO JUST KEEP WINGS LEVEL; APPROX 360 DEGS. THE PERFORMANCE OF THE AIRPLANE WAS SO POOR THAT I THOUGHT I HAD ANOTHER PROB BESIDES THE OPEN DOOR. I HAD A DOOR OPEN INFLT ONCE BEFORE; BUT ON THAT OCCASION I DID NOT EXPERIENCE THE SAME LOSS OF PERFORMANCE. I BEGAN TROUBLE- SHOOTING TO TRY TO FIND ANOTHER PROB THAT WAS CAUSING THE POOR PERFORMANCE. WHILE DOING THIS THE AIRPLANE'S HDG MOMENTARILY STRAYED TO ABOUT 340 DEGS. AT THIS TIME TWR ASKED ME FOR MY HDG. I REPLIED '340 DEGS' (NOT THE HDG I WAS INTENDING TO FLY; JUST A BRIEF; ACCIDENTAL LAPSE IN HDG). TWR SAID THAT THIS HDG WAS A POTENTIAL CONFLICT WITH TFC DEPARTING RWY 36L. TWR THEN GAVE ME A BLIND 'GUT MANEUVER' (THEIR WORDS) TO EVADE THE CONFLICT (I WAS NOT IN RADAR CONTACT YET). THE TWR'S MANEUVER ACTUALLY TOOK ME OVER THE TOP OF RWY 36L. IN RETROSPECT; THAT MANEUVER CONCERNS ME SINCE IT WAS NOT BASED ON ACTUAL DATA. WITH YAWING FORCES PRESENT; I SHOULD HAVE PAID MORE ATTN TO THE AIRPLANE'S ACTUAL HDG; RATHER THAN JUST MAINTAINING WINGS LEVEL. FOR A LACK OF ANY OTHER EXPLANATION; IT APPEARS THAT DOWNDRAFTS FROM THE RAINSHOWER MUST HAVE CONTRIBUTED TO THE AIRPLANE'S INITIAL POOR PERFORMANCE (I WAS FLYING THROUGH MODERATE RAIN; WHICH WAS SOAKING ME AND THE AIRPLANE'S INTERIOR; AND OCCASIONALLY MODERATE TURB). THE ENTIRE EVENT OCCURRED IN THE CLOUDS; CEILING WAS A FEW HUNDRED FT. NO ATTEMPT WAS MADE TO TRY TO CLOSE THE DOOR. RESULTING WIND NOISE MADE COM DIFFICULT. WITH MAX VOLUME I COULD BARELY HEAR ATC'S XMISSIONS. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR FLIES THE BEECHCRAFT BARON FOR A PART 135 NON SCHEDULED AIR FREIGHT ACR. THE 'CTLR PANICKED' AND HAD THE RPTR CROSS THE L RWY (HE WAS HDG THAT WAY) AND HAD ANOTHER ACFT OFF OF THE L RWY CROSS OVER TO THE R. THE ACFT WERE XING IN THE CLOUDS AT A VERY LOW ALT AND MINIMUM SEPARATION. THE RPTR TRIED TO GET THE DOOR CLOSED BY YAWING THE ACFT BUT TO NO AVAIL. THE RPTR BROUGHT THE ACFT BACK AND LATER TALKED TO THE TWR ON THE PHONE. A MECH FOUND THAT THERE WAS A PROB WITH ONE OF THE PINS IN THE DOOR LOCKING MECHANISM. THE RPTR DID NOT DECLARE AN EMER.