What was found
(CAN) IT WAS NOTICED DURING ROUTINE MAINTENANCE THAT THE LT UPLOCK ACTUATOR SUPPORT BRACKETS WERE MISSING THE ATTACH HI-LITES (QTY 6) THRU AFT FRAME (THIS HAS INITIATED A FLEET WIDE INSPECTION AS DIRECTED BY DASH-8-400 AOM 050) AC SN 4033 HAS SUFFERED A STRUCTURAL DAMAGE DUE TO MISSING FASTENERS IN AFT END OF THE BRACKETS FOR THE LT MAIN LANDING GEAR. UPLOCK. MAINTENANCE WILL CHANGE THE ENTIRE SHEAR DIAPHRAGM , THE SUPPORT BRACKET DOUBLER , SUPPORT BRACKET SHIM , ATTACHMENT CLEATS AND REMOVE AND REPLACE BOTH UPLOCK BRACKETS.