Airworthiness Directives; Rolls-Royce plc RB211-524 Series Turbofan Engines

This amendment adopts a new airworthiness directive (AD) that is applicable to certain Rolls-Royce plc RB211-524 series turbofan engines. This action requires initial and repetitive ultrasonic inspections for cracks in fan blade dovetail roots, and, if necessary, replacement with serviceable parts. This action also provides the options of installing improved design fan blades or reworking current fan blades to the improved configuration as terminating action for the inspections. This amendment is prompted by reports of fan blade failures due to dovetail root cracks. The actions specified in this AD are intended to prevent possible multiple fan blade failures, which could result in an uncontained engine failure and damage to the aircraft.