Airworthiness Directives; Eurocopter France Model EC 120B Helicopters

This amendment supersedes an existing airworthiness directive (AD), applicable to Eurocopter France Model EC 120B helicopters, that currently requires, at specified time intervals, inspecting the engine coupling tube for cracks and replacing any cracked engine coupling tube with an airworthy engine coupling tube. This amendment requires, at specified time intervals, visually inspecting and dye-penetrant inspecting the coupling tube for any crack and replacing any cracked coupling tube with a reinforced, airworthy coupling tube. Replacing all coupling tubes and certain engine support fitting components is required on or before March 31, 2000. This amendment is prompted by the discovery of cracks in several coupling tubes. The actions specified by this AD are intended to prevent coupling failure, loss of engine drive, and a subsequent forced landing.