What was found
FLIGHT CREW WERE UNABLE TO CLOSE THE MAIN ENTRANCE DOOR FOLLOWING COMPLETION OF A FLIGHT. MAINTENANCE PERSONNEL INSPECTED AND DISCOVERED A CRACK IN THE MAIN ENTRANCE DOOR ACTUATOR UPPER ATTACHMENT CHANNEL. THE MAIN ENTRANCE DOOR ACTUATOR UPPER ATTACHMENT CHANNEL CRACKED, RESULTING IN STRESS ON THE ACTUATOR UPPER ATTACHMENT FITTING, PN 1159BM502-16, CHANNEL PN 159B10456-23, AND SUPPORT WEB, PN 159B10456-11B IAW SERVICE CENTER DWG 159B10456/ FOLLOWING REMOVAL OF PARTS, NDT WAS COMPLETED TO ENSURE STRUCTURAL INTEGRITY AND REPLACEMENT OF ALL PARTS WAS COMPLETED WITH A NEWLY DESIGNED FITTING THAT ADDED ADDITIONAL FASTENER FOR SUPPORT. A STRESS CRACK IS BELIEVED TO BE INITIATED AT THE MAIN ENTRANCE DOOR ACTUATOR UPPER ATTACH CHANNEL. THIS CHANNEL SUPPORTS THE ACTUATOR UPPER ATTACHMENT FITTING AND IS SUPPORTED BY A WEB FOR LOAD DDISTRIBUTION. ALL ASSOCIATED PARTS WERE ORIGINAL TO THE ACFT AND FAILURE OF THE CHANNEL OCCURRED AT 10,080.9 ACTT AND 4967 ACTL.