What was found
LT WING, IB AND AFT OF SPEEDBRAKE, INSTALLATION FORMED A CRACK AT THE WING T/E AND AT THE FORWARD STIFFENER ATTACHMENT POINT. WING SKIN EXPERIENCES BUFFETING IN AND OUT OF PLANE WITH SPEEDBRAKES DEPLOYED AS A RESULT OF TURBULENCE. THE WING PANEL SKIN IS LARGE AND OILCANS IN AND OUT OF PLANE GENERATING SIGNIFICANT TENSILE FORCE ON THE RIVETS AT THE PERIMETER OF THE PANEL. THE ADDED WING STIFFENER LIMITS THE OILCAN MOVEMENT AND STRESS. CRACK INITIATED AT FORWARD RIVET HOLE FOR ADDED STIFFENER.