Summary
We propose to supersede two existing airworthiness directives (ADs) that apply to General Electric Company (GE) CF6-45 and CF6-50 series turbofan engines with certain low-pressure turbine (LPT) rotor stage 3 disks installed. The existing ADs currently require inspections of high pressure turbine (HPT) and LPT rotors, engine checks, and surveys. Since we issued those ADs, GE has determined that the low- cycle fatigue (LCF) lives of the LPT rotor stage 3 disks affected by those ADs are below the current published engine manual life limits and has introduced a new LPT rotor stage 3 disk part number. This proposed AD would establish a new lower life limit for the LPT rotor stage 3 disks. We are proposing this AD to prevent critical life-limited rotating engine part failure, which could result in an uncontained engine failure and damage to the airplane.