Summary
The FAA is revising an earlier proposal for certain Rolls- Royce plc (RR) RB211 Trent 768-60, 772-60, and 772B-60 model turbofan engines. This action revises the notice of proposed rulemaking (NPRM) by modifying the inspection threshold for ultrasonic inspections (UIs) of the affected low-pressure (LP) compressor blades for both standard operations and non-standard operations (NSO). This action also revises the service information references. The FAA is proposing this airworthiness directive (AD) to address the unsafe condition on these products. Since these actions would impose an additional burden over those in the NPRM, the FAA is reopening the comment period to allow the public the chance to comment on these changes.
DATES: The comment period for the NPRM published in the Federal Register on August 14, 2018 (83 FR 40161), is reopened. The FAA must receive comments on this SNPRM by December 30, 2019.