Airworthiness Directives; Rolls-Royce plc Turbofan Engines

We are superseding an existing airworthiness directive (AD) for all Rolls-Royce plc (RR) RB211-Trent 875-17, RB211-Trent 877-17, RB211-Trent 884-17, RB211-Trent 884B-17, RB211-Trent 892-17, RB211- Trent 892B-17, and RB211-Trent 895-17 turbofan engines. That AD currently requires initial and repetitive ultrasonic inspections (UIs) of certain low-pressure (LP) compressor blades identified by serial number (S/N). This new AD requires the same actions but expands the population of blades. This AD was prompted by the need to add the inspections of the LP compressor blades listed by S/N in Appendices 3H through 3L of RR plc Alert Service Bulletin (ASB) No. RB.211-72-AG244, Revision 4, dated December 22, 2011. We are issuing this AD to prevent multiple LP compressor blades from failing due to blade root cracks, which could lead to uncontained engine failure and damage to the airplane.