Airworthiness Directives; Airbus Helicopters

FAA / Federal Register · 2021-25703

The FAA is adopting a new airworthiness directive (AD) for Airbus Helicopters Model EC 155B and EC155B1 helicopters. This AD was prompted by the failure of a main gearbox (MGB) second stage planet gear. This AD requires replacing the MGB, or as an alternative, replacing the epicyclic reduction gear module for certain serial numbered planet gear assemblies installed on the MGB. This AD also requires inspecting the MGB magnetic plugs and MGB filter for particles, and for certain serial-numbered planet gear assemblies, inspecting the oil sump for particles. Depending on the outcome of these inspections, this AD requires further inspections and replacing certain parts. This AD also prohibits installing certain parts. The FAA is issuing this AD to address the unsafe condition on these products.