Airworthiness Directives; Rolls-Royce plc RB211 Series Turbofan Engines

The FAA is superseding an existing airworthiness directive (AD) for Rolls-Royce plc (RR) models RB211-535E4-37, RB211-535E4-B-37, RB211-535C-37, RB211-535E4-B-75, and RB211-22B-02 turbofan engines. That AD currently requires inspecting certain high pressure (HP) turbine discs, manufactured between 1989 and 1999, for cracks in the rim cooling air holes, and, if necessary, replacing the disc's serviceable parts. This AD requires the same actions but at reduced compliance schedules and adds the RR model RB211-535E4-C turbofan engine to the applicability. This AD results from a report of cracks in a model RB211-524 HP turbine disc that had propagated further than expected. We are issuing this AD to prevent possible disc failure, which could result in an uncontained engine failure and damage to the airplane.