Airworthiness Directives; Rolls-Royce plc Turbofan Engines

We are revising an earlier proposed airworthiness directive (AD) for all Rolls-Royce plc (RR) RB211 Trent 768-60, 772-60, and 772B- 60 turbofan engines. The NPRM proposed to require inspection of the fan case low-pressure (LP) fuel tubes and clips and the fuel oil heat exchanger (FOHE) mounts and hardware. The NPRM was prompted by fuel leaks caused by damage to the fan case LP fuel tube. This supplemental action revises the NPRM by expanding inspections and corrective actions, correcting a part number (P/N) and the costs of compliance, reducing the applicability, providing another method to comply with certain requirements, and giving credit for certain previous actions. We are proposing this SNPRM to prevent failure of the fan case LP fuel tube, which could lead to an in-flight engine shutdown, loss of thrust control, and damage to the airplane.