The Federal Aviation Administration (FAA) has proposed for Airbus A320neo family aircraft operators, which have opted for certain CFM International LEAP-1A engines, to replace potentially unsafe high-pressure turbine (HPT) rotor interstage seals with serviceable parts. The FAA issued the notice of proposed rulemaking (NPRM) after the engine manufacturer notified the regulator about sub-surface anomalies that developed during the manufacturing process of the HPT’s billets.