AD FAA-2017-1122

We are superseding Airworthiness Directive (AD) 2013-02-04 for all Rolls-Royce plc (RR) RB211-Trent 970-84, RB211-Trent 970B-84, RB211-Trent 972-84, RB211-Trent 972B-84, RB211-Trent 977-84, RB211- Trent 977B-84, and RB211-Trent 980-84 turbofan engines. AD 2013-02-04 required on-wing inspections of low-pressure turbine (LPT) disk seal fins and interstage seals when post-flight review indicates Engine Health Monitoring (EHM) vibratory maintenance-alert limits were exceeded in flight. This AD requires additional criteria for the inspection of the stage 2, 3, and 4 LPT disk seal fins and interstage seals and removes the requirement to inspect the stage 5 LPT disk seal fins and interstage seal. This AD was prompted by a Trent 900 engine experiencing increased low-pressure rotor vibration while in flight resulting in an in-flight shutdown (IFSD) and air turnback. We are issuing this AD to address the unsafe condition on these products.