AD 2003-26-03

This amendment adopts a new airworthiness directive (AD), applicable to certain Airbus Model A319, A320, and A321 series airplanes equipped with certain Litton air data inertial reference units (ADIRU). This AD requires modifying the shelf (floor panel) above ADIRU 3, and, for certain airplanes, modifying the polycarbonate guard that covers the ADIRUs, and the ladder located in the avionics compartment, as applicable. This action is necessary to prevent failure of ADIRU 3 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. This action is intended to address the identified unsafe condition.

Final rule.

2003-26-03 Airbus: Amendment 39-13399. Docket 2002-NM-92-AD.

Applicability: Model A319, A320, and A321 series airplanes; certificated in any category; equipped with Litton air data inertial reference units (ADIRU) installed per Airbus Modification 24852, 25108, 25336, 26002, or 28218; except those airplanes on which Airbus Modification 30650 or 30872 has been accomplished.

Compliance: Required as indicated, unless accomplished previously.

To prevent failure of ADIRU 3 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, accomplish the following:

Modification

(a) Within 2 years after the effective date of this AD: Do the modifications specified in paragraphs (a)(1), (a)(2), and (a)(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;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 the effective date of this AD: 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 the effective date of this AD: 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.

Alternative Methods of Compliance

(b) In accordance with 14 CFR 39.19, the Manager, International Branch, ANM-116, FAA, Transport Airplane Directorate, is authorized to approve alternative methods of compliance for this AD.

Incorporation by Reference

(c) The actions shall be done in accordance with Airbus Service Bulletin A320-25-1248, dated February 16, 2001. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from Airbus, 1 Rond Point Maurice Bellonte, 31707 Blagnac Cedex, France. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

Note 1: The subject of this AD is addressed in French airworthiness directive 2002-125(B), dated March 6, 2002.

Effective Date

(d) This amendment becomes effective on January 27, 2004.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to certain Airbus Model A319, A320, and A321 series airplanes equipped with certain Litton air data inertial reference units (ADIRU) that was published in the Federal Register on October 8, 2003 (68 FR 58050). That action proposed to require modifying the shelf (floor panel) above ADIRU 3, and, for certain airplanes, modifying the polycarbonate guard which covers the ADIRUs, and the ladder located in the avionics compartment, as applicable.

Comments

Interested persons have been afforded an opportunity to participate in the making of this amendment. No comments were submitted in response to the proposal or the FAA's determination of the cost to the public.

Conclusion

The FAA has determined that air safety and the public interest require the adoption of the rule as proposed.

Cost Impact

The FAAestimates that 200 airplanes of U.S. registry will be affected by this AD, that it will take approximately 4 work hours per airplane to accomplish the required actions, and that the average labor rate is $65 per work hour. Required parts will cost approximately $300 per airplane. Based on these figures, the cost impact of the AD on U.S. operators is estimated to be $112,000, or $560 per airplane.

The cost impact figure discussed above is based on assumptions that no operator has yet accomplished any of the requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted. The cost impact figures discussed in AD rulemaking actions represent only the time necessary to perform the specific actions actually required by the AD. These figures typically do not include incidental costs, such as the time required to gain access and close up, planning time, or time necessitated by other administrative actions.

Regulatory Impact

The regulations adopted herein will not have a substantial direct effect on the States, on the relationship between the national Government and the States, or on the distribution of power and responsibilities among the various levels of government. Therefore, it is determined that this final rule does not have federalism implications under Executive Order 13132.

For the reasons discussed above, I certify that this action (1) is not a "significant regulatory action" under Executive Order 12866; (2) is not a "significant rule" under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act. A final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it may be obtained from the Rules Docket at the location provided under the caption ADDRESSES.

Listof Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.

Adoption of the Amendment

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows:

PART 39--AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701.

39.13 [Amended]

2. Section 39.13 is amended by adding the following new airworthiness directive: