Airworthiness Directives; Empresa Brasileira de Aeronautica S.A. (EMBRAER) Model ERJ 170 Series Airplanes

The FAA is adopting a new airworthiness directive (AD) for all EMBRAER Model ERJ 170 series airplanes. This AD requires revising the airplane flight manual (AFM) to include certain operational instructions and prohibit dispatch of any flight with the integrated electronic standby system (IESS) inoperative, even though it is allowed by the current version of the Master Minimum Equipment List; and performing a test to determine proper operation of the network interface card (NIC) communications and repairing if necessary. This AD also requires installing a certain software version of the PRIMUS EPIC system, after which the AFM revision must be removed from the AFM. This AD is prompted by reports of temporary loss of all cockpit display units (DU). We are issuing this AD to prevent temporary or possible sustained loss of all modular avionics units (MAU), which triggers a cascade of failures in systems dependent on MAUs functionalities. Such failures could reduce the flightcrew's situational awareness and increase workload and consequently reduce the ability of the flightcrew to maintain the safe flight and landing of the airplane.