Airworthiness Directives; Sikorsky Aircraft Corporation Model S- 61A, D, E, L, N, NM, R, and V Helicopters

Résumé

This amendment supersedes an existing priority letter airworthiness directive (AD), applicable to Sikorsky Aircraft Corporation Model S-61A, D, E, L, N, NM, R, and V helicopters, that currently requires inspecting certain main rotor blade assemblies (blades) to determine if a blade has a blade trailing edge pocket assembly (pocket assembly) that was anodized by Poly-Metal Company during a specified time period, and if so, replacing it with an airworthy blade. This amendment requires the same actions as the existing AD, but corrects two serial numbers in the list of the applicable blades. This amendment is prompted by the manufacturer's issuance of a service bulletin with a revised list of blade serial numbers. The actions specified by this AD are intended to prevent disbonding and separation of portions of the blade, subsequent excessive vibrations, and loss of control of the helicopter.