Airworthiness Directives; Eurocopter France Model SA-365N, SA-365N1, AS-365N2, and SA-366G1 Helicopters

This amendment supersedes an existing airworthiness directive (AD) that currently applies to Eurocopter France (ECF) Model SA 365N, N1, and AS 365N2 helicopters. That AD currently requires inspecting the main gearbox (MGB) suspension diagonal cross-member (diagonal cross-member) for cracks and replacing it with an airworthy part if any crack is found. This amendment requires more frequent inspections of the diagonal cross-member and adding the Model SA-366G1 helicopters to the applicability. This amendment is prompted by several reports of cracks in the diagonal cross-member. The actions specified by this AD are intended to prevent failure of the diagonal cross-member, pivoting of the MGB, severe vibrations, and a subsequent forced landing.