Airworthiness Directives; Rolls-Royce plc Turbofan Engines

We are adopting a new airworthiness directive (AD) for all Rolls-Royce plc (RR) RB211-535E4-37, RB211-535E4-B-37, and RB211-535E4- C-37 turbofan engines. This AD requires reducing the cyclic life limits for certain high-pressure turbine (HPT) disks, removing those disks that have exceeded the new life limit, and replacing them with serviceable parts. This AD was prompted by RR updating the life limits for certain HPT disks. We are issuing this AD to prevent failure of the HPT disk, which could result in uncontained disk release, damage to the engine, and damage to the airplane.