Summary
We propose to adopt a new airworthiness directive (AD) for Eurocopter France Model EC130B4 helicopters. This proposed AD results from mandatory continuing airworthiness information (MCAI) originated by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The aviation authority of France, with which we have a bilateral agreement, states in the MCAI:
This Airworthiness Directive (AD) is issued following the discovery of several cases of loosened rivets in the tube-to-flange attachment of the tail rotor drive center section shaft. In one case, this loosening of rivets was associated with a crack in the tube which started from a loosened-rivet hole. These occurrences can lead to failure of the tail rotor drive center section shaft.
The proposed AD would require actions that are intended to address the unsafe condition caused by cracks and loosened rivets in the tube- to-flange attachment of the tail rotor andthe unsafe condition caused by the out-of-perpendicularity of the No. 1 bearing.