Summary
The FAA proposes to supersede airworthiness directive (AD) 2021-05-05, which applies to all Airbus Helicopters Model SA-365N1, AS- 365N2, AS 365 N3, SA-366G1, EC 155B, and EC155B1 helicopters. AD 2021- 05-05 requires modifying the helicopter by replacing the tail rotor gearbox (TGB) control shaft guide bushes; repetitive inspections (checks) of the oil level of the TGB and, if necessary, filling the oil to the maximum level; repetitive inspections of the TGB magnetic plug and corrective actions if necessary; repetitive replacements of a certain control rod double bearing (bearing); and modifying the helicopter by replacing the TGB. Since the FAA issued AD 2021-05-05, the FAA determined that the magnetic plug inspection interval must be reduced and the compliance time for replacement of the affected part must be reduced. This proposed AD would continue to require certain actions in AD 2021-05-05; and would also reduce the intervals of the magnetic plug inspection, revise the corrective actions if particles are detected, and revise the compliance time for replacement of the affected part, 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.