2019-SW-064-AD; Airbus Helicopters Model AS-365N2, AS 365 N3, EC 155B, EC155B1, and SA-365N1 Helicopters, to Require Inspecting the Tail Rotor Gearbox (TGB) Housing Recess, and Depending on the Inspection Results, Performing More In-depth Inspections and Removing Certain Parts from Service; and Prohibit Installing a TGB Unless it has Passed Certain Inspections and has a New TGB Control Rod Bearin