What was found
(CAN) IT WAS REPORTED TO BELL: THAT THE UPPER LATCH PIN OF THE LEFT CREW DOOR DISENGAGED AT THE SPEED OF 90 KT IN CRUISE FLIGHT. THE CREW DOOR DIDN`T OPEN. CREW ENGAGED THE UPPER LATCH PULLING A BELT ATTACHED ON THE DOOR. AFTER A WHILE, THE SAME UPPER LATCH PIN DISENGAGED AGAIN. (GROUND CREW CONFIRMED THAT ALL LATCH PINS ARE ENGAGED BEFORE TAKEOFF.) THE DOOR SEAL IS PRE TB 505-19-17. (TC# 20190521009)