Summary
We propose to adopt a new airworthiness directive (AD) for Eurocopter France (Eurocopter) Model EC 155B and EC155B1 helicopters. This proposed AD would require repetitively inspecting the lower and upper front and rear fittings (fittings) that attach the upper fin to the fenestron for a crack. If there is a crack, this AD would require removing all four fittings from service. This proposed AD would also require, within a specified time, removing all fittings from service, and the fittings would not be eligible to be installed on any helicopter. This AD is prompted by the loss of an upper fin in flight. The proposed actions are intended to detect a crack in the fittings to prevent loss of the upper fin and subsequent loss of control of the helicopter.