Airworthiness Directives; General Electric Company CF6-6 Series Turbofan Engines

This amendment adopts a new airworthiness directive (AD), that is applicable to General Electric (GE) CF6-6 series turbofan engines. This amendment requires a reduction of the cyclic life limit for certain high pressure turbine rotor (HPTR) rear shafts, and requires removing certain HPTR rear shafts from service before exceeding the new, lower cyclic life limit. In addition, this amendment requires removing from service certain HPTR rear shafts that currently exceed, or will exceed, the new, lower cyclic life limit according to the compliance schedule described in this AD. This amendment is prompted by an updated low-cycle-fatigue (LCF) analysis performed by the manufacturer that resulted in a lower cyclic life limit for certain HPTR rear shaft part numbers (PNs) installed in CF6-6 engines. The actions specified by this AD are intended to prevent cracks in HPTR rear shafts that could result in uncontained engine failure and damage to the airplane.