Airworthiness Directives; Rolls-Royce plc Turbofan Engines

We propose to adopt 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 proposed AD was prompted by RR updating the life limits for certain high-pressure turbine (HPT) disks. This proposed AD would require reducing the cyclic life limits for certain HPT disks, removing those disks that have exceeded the new life limit, and replacing them with serviceable parts. We are proposing 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.