Summary
The FAA proposes to supersede Airworthiness Directive (AD) 2016-23-05, which applies to certain Airbus Helicopters Model SA-365N1, AS-365N2, AS 365 N3, SA-366G1, EC 155B, and EC155B1 helicopters. AD 2016-23-05 requires repetitive checks of the oil level of the tail rotor gearbox and, if necessary, filling the oil to the
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maximum level; and replacement of a certain control rod double bearing (bearing) with a new bearing. Since issuing AD 2016-23-05, the FAA has determined additional inspections, replacements, and modifications are necessary to address the unsafe condition. This proposed AD would retain the requirements of AD 2016-23-05 and would add helicopters to the applicability. This proposed AD would also require modifying the helicopter by replacing the tail gearbox (TGB) control shaft guide bushes; repetitive inspections of the TGB magnetic plug and corrective actions if necessary; repetitive replacements of the bearing; and modifying the helicopterby replacing the TGB; as specified in a European Union Aviation Safety Agency (EASA) AD, which will be incorporated by reference. The FAA is proposing this AD to address the unsafe condition on these products.