2018-SW-045-AD; Leonardo S.p.A. Model AB139 and AW139 Helicopters, to Require Various Inspections of the Main Rotor (M/R) Damper, and Depending on the Inspection Results, Removing from Service or Replacing Certain Parts; also to Require Reducing the Torque of the M/R Damper Hub Attachment Bolts, Marking Parts, Installing a Special Washer, and Installing a Certain Part-Numbered M/R Damper