Airworthiness Directives; General Electric Company GE90 Series Turbofan Engines

This amendment adopts a new airworthiness directive (AD), that is applicable to General Electric Company (GE) GE90 series turbofan engines. This amendment requires removing from service high pressure turbine (HPT) interstage seals, identified by GE as the pre-life- improved rotor (pre-LIR) configuration, and installing a new design, identified by GE as the life improved rotor (LIR) configuration seal. This amendment also requires a new lower life limit for the LIR configuration seal. This amendment is prompted by an uncontained engine failure which occured during a factory development engine ground test. The actions specified by this AD are intended to prevent failure of the HPT interstage seal that could result in an uncontained engine failure and damage to the airplane.