Airworthiness Directives; Eurocopter France Model AS350B, AS350B1, AS350B2, AS350B3, AS350BA, AS350C, AS350D, AS350D1, AS355E, AS355F, AS355F1, AS355F2, and AS355N Helicopters

This amendment supersedes an existing airworthiness directive (AD) for Societe Nationale Industrielle Aerospatiale (currently Eurocopter France) Model AS350 and AS355 series helicopters that currently requires inspecting the fuselage frame (frame) for a crack at the fuselage-to-tailboom interface and replacing or repairing, as necessary. That AD also requires a fastener torque check and retorquing, as necessary. This amendment retains the requirements of the existing AD but would increase the inspection interval from 1,200 hours time-in-service (TIS) to 2,500 hours or 6 years TIS, whichever occurs first. This amendment revises the time interval for inspecting the frame at the fuselage-to-tailboom interface to coincide with the inspection interval specified in the maintenance manual. The actions specified by this AD are intended to eliminate confusion and unnecessary costs and to prevent a cracked frame, tailboom failure, and subsequent loss of control of the helicopter.