Airworthiness Directives; Eurocopter France Model SA-366G1 Helicopters

This amendment adopts a new airworthiness directive (AD), applicable to Eurocopter France Model SA-366G1 helicopters, with certain main rotor head frequency adapters (frequency adapters) installed. This proposal requires inspecting the frequency adapter to determine if a certain frequency adapter is installed, and if so, removing and discarding the frequency adapter and replacing it with an airworthy frequency adapter before further flight. This amendment is prompted by a report of disbonding of the metal center section of a frequency adapter from the elastomer, caused by a lack of adherence during the production process. The actions specified by this AD are intended to prevent vibrations caused by disbonding of the center section of a frequency adapter from the elastomer, that could result in loss of control of the helicopter.