Summary
We propose to supersede two existing airworthiness directives (ADs) that apply to certain Airbus Model A330-200, A330-200 Freighter, A300-300, A340-200, A340-300, A340-500, and A340-600 series airplanes. One existing AD currently requires revising the airplane flight manual (AFM) to include appropriate operational procedures to prevent the air data inertial reference unit (ADIRU) from providing erroneous data to other airplane systems. The other existing AD currently requires revising the AFM to provide appropriate operational procedures to prevent the airplane flight directors (FDs), autopilot (AP), and auto- thrust re-engagement in the event of airspeed sources providing similar but erroneous data. Since we issued that AD, we have determined that new software standards for the flight control primary computers (FCPCs) are necessary to inhibit autopilot re-engagement under unreliable airspeed conditions. This proposed AD would require that operators modify or replace all threeFCPCs with new software standards. This proposed AD would also remove certain airplanes from the applicability. We are proposing this AD to prevent autopilot engagement under unreliable airspeed conditions, which could result in reduced controllability of the airplane.