Airworthiness Directives; Airbus Helicopters (Previously Eurocopter France (Eurocopter) Helicopters)

概要

We propose to supersede airworthiness directive (AD) 2007-25- 08 for Eurocopter Model SA-365 N1, AS-365N2, AS 365 N3, SA-366G1, EC 155B, and EC155B1 helicopters. AD 2007-25-08 currently requires checking the tail rotor gearbox (TGB) oil level, inspecting the magnetic plug for chips and either replacing the TGB or further inspecting for axial play in the tail rotor hub pitch change control spider (spider), and if axial play is found in the spider, replacing the pitch control rod assembly double bearing (bearing). Since we issued the AD 2007-25-08, we have received reports of new occurrences of loss of yaw control due to failure of the control rod bearing. This proposed AD would retain some of the requirements of AD 2007-25-08, revise the inspections for play in the double bearing to improve the detection of play, require replacing the TGB control shaft guide bushes, clarify the criteria concerning particle detection, and change the inspection for play in the double bearing after the guide bushes have been replaced. The proposed actions are intended to prevent damage to the bearing resulting in end play, loss of tail rotor pitch control, and subsequent loss of control of the helicopt