Airworthiness Directive · Amendment 39-15650 · Airbus Model A318, A319, A320, and A321 Series Airplanes Equipped With Certain Northrop Grumman (Formerly Litton) Air Data Inertial Reference Units
Airbus Model A318, A319, A320, and A321 Series Airplanes Equipped With Certain Northrop Grumman (Formerly Litton) Air Data Inertial Reference Units
This AD applies to Airbus Model A318, A319, A320, and A321 series airplanes, certificated in any category; equipped with at least one Northrop Grumman (formerly Litton) air data inertial reference unit (ADIRU), part number (P/N) 465020-0303-0307, -0308, -0309, -0312, -0314, -0315, or -0316; except airplanes equipped with three ADIRUs having P/N 465020-0303-0316 and on which Airbus Modification 30650 or 30872 has been incorporated in production, or on which Airbus Service Bulletin A320-25-1248 has been applied in service.
The FAA is superseding an existing airworthiness directive (AD), which applies to certain Airbus Model A319, A320, and A321 series airplanes equipped with certain Litton air data inertial reference units (ADIRUs). That AD currently requires modifying the shelf (floor panel) above ADIRU 3, modifying the polycarbonate guard that covers the ADIRUs for certain airplanes, and modifying the ladder located in the avionics compartment for certain airplanes. This new AD requires those modifications on additional airplanes. This new AD also requires replacing all three ADIRUs with improved ADIRUs. This new AD also adds Model A318 series airplanes to the applicability. This AD results from reports that "NAV IR FAULT" messages have occurred during takeoff due to failure of an ADIRU and subsequent analysis showing that the shelf modification has not sufficiently addressed failure of an ADIRU. We are issuing this AD to prevent failure of an ADIRU during flight, which could result in loss of one source of critical attitude and airspeed data and reduce the ability of the flightcrew to control the airplane.
You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.
For Model A319, A320, and A321 series airplanes, equipped with any Litton ADIRU installed in accordance with Airbus Modification 24852, 25108, 25336, 26002, or 28218: Within 2 years after January 27, 2004 (the effective date of AD 2003-26-03), do the modifications specified in paragraphs (f)(1), (f)(2), and (f)(3) of this AD, as applicable, in accordance with paragraphs A. through D. of the Accomplishment Instructions of Airbus Service Bulletin A320-25-1248, dated February 16, 2001; or Airbus Service Bulletin A320-25-1248, Revision 01, dated April 16, 2003; as applicable.
(1) For all airplanes: Modify the shelf (floor panel) above ADIRU 3 by installing shims between the shelf and the webs of the shelf support structure.
(2) For airplanes with Airbus Modification 25900P3941 or Airbus Service Bulletin A320-25-1200 accomplished as of January 27, 2004: Modify the polycarbonate guard (umbrella) protecting the ADIRUs by installing shims between the guard and the shelf support structure.
(3) For airplanes with Airbus Modification 23027P2852 or Airbus Service Bulletin A320-52-1038 accomplished as of January 27, 2004: Modify the ladder located in the avionics compartment by machining the slot at the foot of the ladder to increase the depth by 0.236 inch.
For all airplanes equipped with any ADIRU installed in accordance with Airbus Modification 31070, 31742, or 35517, except airplanes on which Airbus Modification 30650 or 30872 has been accomplished in production: Within 46 months after the effective date of this AD, modify the ADIRU shelf supports by accomplishing all of the applicable actions specified in the Accomplishment Instructions of Airbus Service Bulletin A320-25-1248, Revision 01, dated April 16, 2003.
For all airplanes except those on which Airbus Modification 35517 has been incorporated in production: Within 46 months after the effective date of this AD, replace all three ADIRUs with improved ADIRUs having P/N 465020-0303-0316 in accordance with the Accomplishment Instructions of Airbus Service Bulletin A320-34-1350, dated March 20, 2006; or Airbus Service Bulletin A320-34-1350, Revision 01, dated December 12, 2007.
