Summary
The FAA proposes to adopt a new airworthiness directive (AD) for all Airbus Helicopters Model AS-365N2, AS 365 N3, EC 155B, EC155B1, and SA-365N1 helicopters. This proposed AD was prompted by a large amount of critical scale particles found on the tail rotor gearbox (TGB) chip detector magnetic plug during an unscheduled check of the TGB. The particles belonged to the double bearing (pitch control rod bearing) installed inside the TGB. This proposed AD would require repetitive inspections of the TGB chip detector for particles, analyzing any particles collected, performing a double bearing washing, repetitive replacements of certain part-numbered double bearings, and corrective actions if necessary, as specified in a European Union Aviation Safety Agency (EASA) AD, which is proposed for incorporation by reference (IBR). The FAA is proposing this AD to address the unsafe condition on these products.