Airworthiness Directives; Rolls-Royce Deutschland Ltd & Co KG Dart 528, 529, 529D, 531, 532, 535, 542, and 552 Series Turboprop Engines

The FAA is adopting a new airworthiness directive (AD) for Rolls-Royce Deutschland Ltd & Co KG (RRD) (formerly Rolls-Royce plc) Dart 528-7E, 529-7H, -7E, -8E, -8H, -8X, -8Y, -8Z, 529D-7E, -7H, -8E, - 8H, -8X, -8Y, -8Z, 531, 532-2L, -7, -7N, -7P, -7L, -7R, 535-2, -7R, 542-4, -4K, -10, -10J, -10K, 552-2, 552-7, and -7R turboprop engines. This AD requires removal of any Sermetel coating (Omat 7/46) from certain high pressure (HP) turbine discs and intermediate pressure (IP) turbine discs, and inspection of discs after coating removal. This AD is prompted by reports of Sermetel coating (Omat 7/46) applied to certain turbine discs which, if allowed to remain on the discs would react adversely with the disc dry film lubricant, and could result in uncontained HP or IP turbine disc failure, resulting in possible damage to the airplane. We are issuing this AD to prevent uncontained HP or IP turbine disc failure, which could result in damage to the airplane.