Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to Eurocopter France Model SA-366G1 helicopters, with certain main rotor head frequency adapters (frequency adapters) installed. This proposal would require 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 proposal is prompted by one 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 the proposed 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.