AN ATX CITATION III HAD A LOUD AIR LEAK SQUEAL IN THE CABIN RIGHT AFTER TKOF. THE FO WENT BACK TO CHK THE SOURCE OF THE SQUEAL AND POSSIBLY OPENED THE DOOR INFLT.

Narrative

HAD A NORMAL TKOF. SHORTLY AFTERWARDS; HEARD AN AIR NOISE COMING FROM CABIN AREA. THE FO WENT IN THE BACK TO INVESTIGATE (ANNUNCIATOR PANEL CLR). WHEN THE FO WAS IN THE CABIN AREA; THE CABIN DOOR OPENED. THE FO STAYED IN THE BACK; CALMED THE PAX. EXECUTED AN EMER LNDG. UPON REFLECTION; I THINK THE AIR NOISE WAS NOT A MAJOR PROB; POSSIBLY A LEAKY DOOR SEAL; OR A LEAK FROM THE OVERHEAD DUCT. THE FO STATED THAT HE HEARD THE NOISE FROM THE DOOR AREA; AND HE WANTED TO VERIFY THAT THE DOOR WAS LATCHED. HE SAID HE MOVED THE HANDLE; AND ABOUT THAT TIME; THE DOOR OPENED. I THINK THE FO OPENED THE DOOR INFLT! IT DISAPPOINTS ME THAT THE FO EVEN TOUCHED THE DOOR TO BEGIN WITH. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR FLIES A C650; CITATION III. THE FO DID NOT HAVE MUCH EXPERIENCE IN THE C650. THE RPTR BELIEVES THAT THE FO MOVED THE HANDLE IN THE WRONG DIRECTION; OPENING THE DOOR. THE RPTR BELIEVES THAT THE DOOR LOCKING PINS MAY HAVE BEEN OUT OF ALIGNMENT ALLOWING THE ANNUNCIATOR LIGHT TO BE OFF WHEN THE DOOR WAS NOT FULLY LOCKED. THE FO LOCKED THE DOOR BEFORE TKOF AND CHKED THE PINS BUT PROBABLY DID NOT USE A FLASHLIGHT AND PROBABLY DID NOT KNOW TO MOVE THE HANDLE HARD PAST 90 DEGS. THE DOOR HAD BEEN MODIFIED; COVERING UP ONE OF THE WINDOWS USED TO CHK THE LOCKING PINS. THE ACFT IS BACK AT THE FACTORY NOW GETTING REPAIRS TO THE DOOR AND ITS MECHANISM. THE DOOR OPENS DOWNWARD TO FORM A STEP AND DRAGGED ON THE RWY. THE RPTR NEVER SAW A DOOR WARNING LIGHT. HE HAS BEEN CRITICIZED FOR SENDING FO BACK TO CHK THE DOOR. THE ACFT IMMEDIATELY RETURNED TO LAND.