Airworthiness Directives; Pratt & Whitney PW4164 and PW4168 Series Turbofan Engines

This amendment adopts a new airworthiness directive (AD) that is applicable to certain Pratt & Whitney PW4164 and PW4168 series turbofan engines. This action requires initial and repetitive visual inspections of the fan blades for surface damage and cracks, initial and repetitive lubrication of the fan blade part span shrouds, a one time ultrasonic inspection (UI) of the fan blade root attachment area for cracks, and a one time fan blade root attachment front corner radii inspection for proper dimension. Also, this AD requires visual inspection of the fan blades and removal of fan blades damaged by a bird strike as well as removal of blades immediately adjacent to damaged blades. In addition, this AD requires installation of an improved fan blade assembly as terminating action to the inspection requirements of this AD. This amendment is prompted by a report of a high N1 rotor imbalance and liberation of the fan containment system causing loss of structural support of the engine inlet cowl, following loss of a fan blade during a test. The actions specified in this AD are intended to prevent fan blade failure and separation at the root section, which could result in high N1 rotor imbalance, and liberation of the fan containment system, which can hazard the aircraft.