Airworthiness Directives; Eurocopter France (ECF) Model AS350B, B1, B2, B3, BA, and D; and AS355E, F, F1, F2, and N Helicopters

We are superseding an existing airworthiness directive (AD) for the specified ECF model helicopters. This AD results from a mandatory continuing airworthiness information (MCAI) AD issued by the European Aviation Safety Agency (EASA), which is the Technical Agent for the Member States of the European Union. The MCAI AD states that some cracks have been discovered in the spar of the upper fin on Model AS355N helicopters. Due to the fin design similarity between AS350 and AS355 helicopters, this AD action applies to both helicopter models. Modifying the upper and lower fin attachment is intended to prevent failure of a spar, loss of a fin, a separated fin hitting a rotor, and subsequent loss of control of a helicopter.