Airworthiness Directives; Honeywell International Inc., Primus EPIC and Primus APEX Flight Management Systems, Installed on, but not Limited to, Empresa Brasileira de Aeronautica S.A. (EMBRAER) Model ERJ 170 and ERJ 190 Airplanes, and Pilatus Aircraft Ltd. Model PC-12/47E Airplanes

We are adopting a new airworthiness directive (AD) for certain Honeywell International Inc., Primus EPIC and Primus APEX flight management systems (FMS), as installed on the airplanes described above. This AD requires revising the Limitations section of the airplane flight manual to incorporate the procedures necessary to recover from or work around a software anomaly in the FMS. This AD results from discovery of software anomalies which, in certain situations, can cause the FMS to generate misleading navigational guidance to the pilots and to the autopilot system of various airplanes having this same system software. We are issuing this AD to provide the flightcrew with procedures to recover from or work around these software anomalies during flight, which could lead to an airplane departing from its scheduled flight path, and result in possible collision with other aircraft or terrain.