AD FAA-2014-0169

We are adopting a new airworthiness directive (AD) for certain The Boeing Company Model 747-8 and 747-8F series airplanes powered by certain General Electric (GE) engines. This AD requires removing certain defective software and installing new, improved software. This AD was prompted by a determination that the existing electronic engine control (EEC) software logic can prevent stowage of the thrust reversers (TRs) during certain circumstances, which could cause the TRs to move back to the deployed position. We are issuing this AD to prevent in-flight deployment of one or more TRs due to loss of the TR auto restow function, which could result in inadequate climb performance at an altitude insufficient for recovery, and consequent uncontrolled flight into terrain.