AD FAA-2017-1036

The FAA is revising a notice of proposed rulemaking (NPRM) that applied to certain Airbus Helicopters Model AS-365N2, AS 365 N3, SA-365N, and SA-365N1 helicopters. The NPRM proposed to require either replacing the main gearbox (MGB) or as an alternative, replacing the epicyclic reduction gear module for certain serial numbered planet gear assemblies installed on the MGB. The NPRM also proposed to require inspecting the MGB magnetic plugs and oil filter for particles and, depending on the outcome of the inspection, further inspections and replacing certain parts. The NPRM was prompted by the failure of an MGB second stage planet gear. This action revises the NPRM by expanding the applicability to include all Airbus Helicopters Model AS-365N2, AS 365 N3, SA-365N, and SA-365N1 helicopters. Since these actions impose an additional burden over that proposed in the NPRM, the FAA is reopening the comment period to allow the public the chance to comment on these proposed changes.