Summary
The FAA proposes to adopt a new airworthiness directive (AD) for all Airbus SAS Model A320-251N and -271N airplanes, and Model A321- 251N, -253N, -271N, and -272N airplanes. This proposed AD was prompted by reports that the regulated bleed temperature was measured above the design target with a temperature regulation shift phenomenon, and investigation results show that incorrect temperature regulation can degrade pneumatic system components located downstream of the pre- cooler. This proposed AD would require uploading improved bleed monitoring computer (BMC) software (SW), as specified in a European Aviation Safety Agency (EASA) AD, which will be incorporated by reference. The FAA is proposing this AD to address the unsafe condition on these products.