Airworthiness Directives; CFM International, S.A. Turbofan Engines

FAA / Federal Register · 2021-05600

The FAA is revising a notice of proposed rulemaking (NPRM) that applied to certain CFM International, S.A. (CFM) CFM56-5B, CFM56- 5C, and CFM56-7B model turbofan engines with a certain rotating air high-pressure turbine (HPT) front seal. This action revises the NPRM by requiring CFM56-5B or CFM56-7B model turbofan engines with an installed reconfigured rotating air HPT front seal, which was previously installed and operated in a CFM56-5C model turbofan engine, to follow the removal requirements for the CFM56-5C model turbofan engine. 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 agency is requesting comments on this SNPRM.