Airworthiness Directives; Bell Helicopter Textron Canada Model 407 Helicopters

This amendment supersedes an existing emergency airworthiness directive (EAD), which was sent previously to all known U.S. owners and operators of Bell Helicopter Textron Canada (Bell) helicopters by individual letters. That EAD requires a visual check to ensure that the two swashplate drive link cup washers (cup washers) are installed correctly. If a cup washer is installed incorrectly, removing and replacing the swashplate outer ring, each cup washer, bearing and liner, and drive link where the cup washer was installed incorrectly are also required. This amendment requires the same actions as the existing EAD, but clarifies that only the visual check may be performed by the owner/operator. This amendment is prompted by two reported failures of the stud portion of the swashplate drive link. The actions specified by this AD are intended to detect an incorrectly installed cup washer, which could limit the travel of the swashplate outer ring and lead to failure of the stud portion of the swashplate drive link, and subsequent loss of control of the helicopter.