AD FAA-2012-0423

We are superseding two existing airworthiness directives (AD) for all Embraer S.A. Model ERJ 170 and ERJ 190 airplanes. Those ADs currently require revising the airplane flight manual (AFM) to introduce limitations for the use of auxiliary power unit (APU) bleed and to prohibit dispatch with a failed air management system (AMS) controller card. This new AD requires replacing the AMS controller processor module with one containing new software, and a new AFM revision. This AD was prompted by reports of the possible loss of automatic activation of the engine inlet ice protection system. We are issuing this AD to prevent the possibility of a right-hand (RH) engine compressor stall after the APU becomes the active bleed source for the left side, which may result in an engine failure; and to prevent the intermittent communication failure between the AMS controller cards and both secondary power distribution assemblies (SPDAs), which could lead to the loss of automatic activation of the engine inlet ice protection system when flying in icing conditions, which could result in ice accretion in the engine inlet and subsequent dual engine failure.