BE90 DOOR OPENED DURING FLT TEST AT MAX DIFFERENTIAL CABIN ALT. ACFT NOISE. FLT TEST ACTIVITY.

Narrative

THE CAPT; 1 PAX AND MYSELF WERE ON A MAINT TEST FLT OF OUR KING AIR A90. A FEW MINOR SQUAWKS HAD BEEN WORKED ON BUT PRIMARILY WE WERE TESTING THE NOISE FOR THE CABIN DOOR. AN EARLIER FLT WAS EXTREMELY NOISY; SO WE HAD THE DOOR SEAL REPLACED. (TO CLARIFY; THE OWNER THOUGHT THE SEAL WAS NOISY AND IT WAS; SO WE HAD IT REPLACED.) THIS WAS THE FIRST AND ONLY TEST FLT FOR THE DOOR. I TOOK OFF AND CLBED UP TO 14500 FT WITH THE CAPT IN THE L SEAT. UPON REACHING 14500 FT AND IN RADAR CONTACT WITH WICHITA APCH; THE CAPT LEFT HIS SEAT AND WENT BACK TO SEE IF THE DOOR HAD SEALED OR IF IT WAS LOUD. FROM MY POS; THE DOOR SEEMED MUCH BETTER THAN IT HAD BEEN. I NOTICED NO ANNUNCIATOR LIGHTS 'ON' THAT WOULD SHOW IF THE DOOR HAD NOT BEEN LATCHED. THEN I HEARD A LOUD POP AND WAS MOMENTARILY PUSHED BACK IN MY SEAT. IMMEDIATELY I TURNED AROUND AND SAW THE DOOR WAS OPEN; SO I RETARDED THE PWR LEVERS. I SLOWED THE ACFT DOWN AND WAS IN A DSCNT WHEN I LOOKED BACK ONCE MORE TO SEE IF THE CAPT WAS STILL IN THE ACFT. ON MY FIRST LOOK BACK; I DID NOT SEE HIM BUT THIS TIME I DID. UPON REACHING APPROX 13000 FT THE CAPT WAS ABLE TO COME BACK TO THE COCKPIT AND HE TOOK CTL OF THE ACFT; HE DECLARED AN EMER WITH WICHITA APCH AND WE LANDED AT MID-CONTINENT WITHOUT MUCH PROB. MY ROLE IN THE INCIDENT WAS I WAS FLYING. I HAD NO PART OF CLOSING THE DOOR. I THINK IT WAS A MAINT PROB AND AM VERY HAPPY THE CAPT HAD A SEAT BELT ON IN THE BACK. THE PAX WAS OK. SUPPLEMENTAL INFO FROM ACN 320204: I LEFT THE COCKPIT TO GO TO THE CABIN TO MONITOR POSSIBLE AIR LEAKS. WHILE FEELING AROUND ON THE DOOR; THE DOOR EXPLOSIVELY OPENED WHILE AT 14500 MSL; WHICH WAS AT MAX DIFFERENTIAL ON THE PRESSURIZATION. THE FAA IS LOOKING AT THE DOOR TO TRY TO DETERMINE WHAT CAUSED IT TO OPEN IN FLT. I FEEL THAT THE DOOR HAS A PROB AND THAT IT IS POSSIBLY BOWING OUT IN FLT. I ALSO FEEL THAT I SHOULD NOT HAVE TOUCHED THE DOOR DURING FLT. I AM NOT SURE THAT I WAS A CONTRIBUTING FACTOR TO THE DOOR COMING OPEN; BUT I FEEL THAT IF I WAS THEN IT COULD HAVE OPENED IN FLT IF A PAX WAS NOT SEATED AND MOVING ABOUT IN THE CABIN; THEY COULD HAVE DONE THE SAME THING BY LOSING THEIR BALANCE AND PUTTING THEIR HAND ON THE DOOR TO CATCH THEMSELVES. 13000 HRS TOTAL TIME ON AIRFRAME.