Airworthiness Directives; Bell Helicopter Textron Canada Limited Model 407 Helicopters

This amendment supersedes an existing airworthiness directive (AD) for Bell Helicopter Textron Canada Limited (BHTCL) Model 407 helicopters that requires visually inspecting the brackets that attach the horizontal stabilizer slat (slat) to the stabilizer for a crack. If a crack is found, that AD also requires replacing the slat assembly before further flight. Also, that AD requires installing airworthy, segmented slat assemblies by a specified date. Installing segmented slat assemblies was considered terminating action for the requirements of that AD. This amendment requires, initially and at certain time intervals, checking each slat assembly for a cracked bracket and, if a crack is found, replacing any unairworthy slat assembly with an improved, airworthy slat assembly. This amendment also requires replacing, modifying, and installing identification plates on slats on certain helicopters at specified time intervals. This amendment is prompted by two additional reports of cracked brackets. The actions specified by this AD are intended to prevent a slat from separating, contacting a rotor blade, and resulting in subsequent loss of control of the helicopter.