Airworthiness Directives; Eurocopter France Model AS-350B, BA, B1, B2, B3, C, D, and D1, and AS-355E, F, F1, F2 and N Helicopters

This amendment supersedes an existing airworthiness directive (AD) for Eurocopter France Model AS-350B, BA, B1, B2, C, D, and D1, and AS-355E, F, F1, and F2 helicopters. That AD currently requires inspections of the main rotor head components, the main gearbox (MGB) suspension bars, and the ground resonance prevention system components. This amendment requires those same inspections, but would also apply to Model AS-350B3 and AS-355N helicopters. This amendment is prompted by the inadvertent omission of those model helicopters from the previous AD. The actions specified by this AD are intended to prevent ground resonance due to reduced structural stiffness, which could lead to failure of a main rotor head or MGB suspension component and subsequent loss of control of the helicopter.