Airworthiness Directives; General Electric Company Turbofan Engines

We are adopting a new airworthiness directive (AD) for all General Electric Company (GE) GEnx turbofan engine models. This AD was prompted by reports of GEnx-1B and GEnx-2B engines experiencing power loss in ice crystal icing (ICI) conditions. This AD precludes the use of full authority digital engine control (FADEC) software, version B175 or earlier, in GEnx-1B engines, and the use of FADEC software, version C065 or earlier, in GEnx-2B engines. We are issuing this AD to prevent engine failure, loss of thrust control, and damage to the airplane.