Airworthiness Directives; CFM International CFM56-5B and -7B Series Turbofan Engines

This amendment adopts a new airworthiness directive (AD), that is applicable to CFM International (CFMI) CFM56-5B and -7B series turbofan engines. This amendment requires retirement of stage 2 low pressure turbine (LPT) nozzle segments and stage 3 LPT nozzle segments, listed in Table 1 of this AD, from service before accumulating 25,000 cycles-since-new (CSN) or at the next LPT module shop visit when either stage 2 LPT nozzle segments or stage 3 LPT nozzle segments are exposed, whichever occurs first. This amendment also requires installation of new design (either new or reworked) nozzle segments, that will aid in containment of the LPT rotor in the event of LPT shaft failure. This amendment is prompted by a report of an LPT shaft failure caused by a hydromechanical unit (HMU) malfunction that induced a higher than anticipated LPT rotor overspeed. The actions specified by this AD are intended to aid in containment of the LPT rotor in the event of LPT shaft failure, which could result in uncontained engine failure and damage to the airplane.