Action
Final rule.
Summary
The FAA is superseding Airworthiness Directive (AD) 2012-02-07 for certain General Electric Company (GE) CF6-45 and CF6-50 series model turbofan engines with a specified low-pressure turbine (LPT) rotor stage 3 disk installed. AD 2012-02-07 required inspections of high-pressure turbine (HPT) and LPT rotors, engine checks, vibration surveys, an optional LPT rotor stage 3 disk removal after a failed HPT blade borescope inspection (BSI) or a failed engine core vibration survey, established a lower life limit for the affected LPT rotor stage 3 disks, and required removing these disks from service at times determined by a drawdown plan. This AD was prompted by the occurrence of four events of separation of the LPT rotor assembly, which resulted in the LPT rotor assembly departing the rear of the engine. This AD requires inspections of HPT and LPT rotor stage 1 and stage 2 blades, vibration surveys, and use of a lower life limit for the affected LPT rotor stage 3 disks and, as terminating action to the inspections, engine checks, and vibration surveys, this AD requires removal and replacement of the LPT rotor stage 3 disk with a redesigned LPT rotor stage 3 disk. This AD also requires revising the compliance time of the drawdown plan for the removal and replacement of the LPT rotor stage 3 disk and prohibits the installation or reinstallation of certain LPT rotor stage 3 disks. The FAA is issuing this AD to address the unsafe condition on these products.