Airworthiness Directives; McDonnell Douglas Helicopter Systems MD900 Helicopters

This amendment supersedes an existing priority letter airworthiness directive (AD), applicable to McDonnell Douglas Helicopter Systems (MDHS) Model MD900 helicopters, which prohibits flight or ground operations of helicopters with a certain adjustable collective drive link assembly (link assembly) installed. This amendment requires installation of a redesigned airworthy link assembly after which further operations are permitted. This amendment is prompted by recent incidents in which the link assembly failed during flight. The actions specified by this AD are intended to prevent failure of the link assembly, which could result in loss of control of the helicopter.