[Federal Register Volume 68, Number 195 (Wednesday, October 8, 2003)]
[Proposed Rules]
[Pages 58050-58051]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-25494]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2002-NM-92-AD]
RIN 2120-AA64


Airworthiness Directives; Airbus Model A319, A320, and A321 
Series Airplanes Equipped with Certain Litton Air Data Inertial 
Reference Units

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new 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). This proposal would 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. 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.

DATES: Comments must be received by November 7, 2003.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2002-NM-92-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056. Comments may be inspected at this 
location between 9 a.m. and 3 p.m., Monday through Friday, except 
Federal holidays. Comments may be submitted via fax to (425) 227-1232. 
Comments may also be sent via the Internet using the following address: 
[email protected]. Comments sent via fax or the Internet must 
contain ``Docket No. 2002-NM-92-AD'' in the subject line and need not 
be submitted in triplicate. Comments sent via the Internet as attached 
electronic files must be formatted in Microsoft Word 97 or 2000 or 
ASCII text.
    The service information referenced in the proposed rule may be 
obtained from Airbus Industrie, 1 Rond Point Maurice Bellonte, 31707 
Blagnac Cedex, France. This information may be examined at the FAA, 
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington.

FOR FURTHER INFORMATION CONTACT: Tim Dulin, Aerospace Engineer, 
International Branch, ANM-116, FAA, Transport Airplane Directorate, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 
227-2141; fax (425) 227-1149.

SUPPLEMENTARY INFORMATION:

Comments Invited

    Interested persons are invited to participate in the making of the 
proposed rule by submitting such written data, views, or arguments as 
they may desire. Communications shall identify the Rules Docket number 
and be submitted in triplicate to the address specified above. All 
communications received on or before the closing date for comments, 
specified above, will be considered before taking action on the 
proposed rule. The proposals contained in this action may be changed in 
light of the comments received.
    Submit comments using the following format:
    [sbull] Organize comments issue-by-issue. For example, discuss a 
request to change the compliance time and a request to change the 
service bulletin reference as two separate issues.
    [sbull] For each issue, state what specific change to the proposed 
AD is being requested.
    [sbull] Include justification (e.g., reasons or data) for each 
request.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the proposed rule. All 
comments submitted will be available, both before and after the closing 
date for comments, in the Rules Docket for examination by interested 
persons. A report summarizing each FAA-public contact concerned with 
the substance of this proposal will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this action must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 2002-NM-92-AD.'' The postcard will be date stamped and 
returned to the commenter.

Availability of NPRMs

    Any person may obtain a copy of this NPRM by submitting a request 
to the FAA, Transport Airplane Directorate, ANM-114, Attention: Rules 
Docket No. 2002-NM-92-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The Direction Generale de l'Aviation Civile (DGAC), which is the 
airworthiness authority for France, notified the FAA that an unsafe 
condition may exist on certain Airbus Model A319, A320, and A321 series 
airplanes equipped with certain Litton air data inertial reference 
units (ADIRU). The DGAC advises that operators have reported that ``NAV 
IR FAULT'' messages have occurred during takeoff on several of these 
airplanes due to failure of ADIRU 3. Investigation revealed that 
vibrations during takeoff may cause contact between ADIRU 3 and the 
shelf (floor panel) above it, due to minimal clearance between the 
shelf and the ADIRU. Such contact may cause excessive vertical 
acceleration, which could result in failure of ADIRU 3. Due to its 
location on the shelf, ADIRU 3 is more sensitive to vibration than the 
other two ADIRUs. Failure of ADIRU 3 during flight could result in loss 
of one source of critical attitude and airspeed data and reduce the 
ability of the flightcrew to control the airplane.

Explanation of Relevant Service Information

    Airbus has issued Service Bulletin A320-25-1248, dated February 16, 
2001, which describes procedures for modifying the shelf (floor panel) 
above the Litton ADIRUs by installing shims on the webs of the shelf 
support structure in the avionics rack. In addition, for certain 
airplanes, the service bulletin includes procedures for modifying the 
polycarbonate guard

[[Page 58051]]

which covers the ADIRUs, and machining the ladder located in the 
avionics compartment to increase the depth of the slot at the foot of 
the ladder, as applicable. Accomplishment of the actions specified in 
the service bulletin is intended to adequately address the identified 
unsafe condition. The DGAC classified this service bulletin as 
mandatory and issued French airworthiness directive 2002-125(B), dated 
March 6, 2002, to ensure the continued airworthiness of these airplanes 
in France.

FAA's Conclusions

    These airplane models are manufactured in France and are type 
certificated for operation in the United States under the provisions of 
section 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and 
the applicable bilateral airworthiness agreement. Pursuant to this 
bilateral airworthiness agreement, the DGAC has kept the FAA informed 
of the situation described above. The FAA has examined the findings of 
the DGAC reviewed all available information, and determined that AD 
action is necessary for products of this type design that are 
certificated for operation in the United States.

Explanation of Requirements of Proposed Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on other airplanes of the same type design registered 
in the United States, the proposed AD would require accomplishment of 
the actions specified in the service bulletin described previously, 
except as discussed below.

Differences Between the Proposed Rule and the French Airworthiness 
Directive

    Operators should note that, although the French airworthiness 
directive contains operational dispatch restrictions for airplanes with 
one ADIRU inoperative, this proposed AD does not include these 
restrictions because the FAA-approved Master Minimum Equipment List 
already restricts operations accordingly.

Cost Impact

    The FAA estimates that 200 airplanes of U.S. registry would be 
affected by this proposed AD, that it would take approximately 4 work 
hours per airplane to accomplish the proposed modification of the 
shelf, and that the average labor rate is $65 per work hour. Required 
parts would cost approximately $300 per airplane. Based on these 
figures, the cost impact of the proposed 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 proposed 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 proposed herein would 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 proposal would not have federalism implications 
under Executive Order 13132.
    For the reasons discussed above, I certify that this proposed 
regulation (1) is not a ``significant regulatory action'' under 
Executive Order 12866; (2) is not a ``significant rule'' under the DOT 
Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); 
and (3) if promulgated, 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 copy of the draft 
regulatory evaluation prepared for this action is contained in the 
Rules Docket. A copy of it may be obtained by contacting the Rules 
Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration proposes to amend 
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.


Sec.  39.13  [Amended]

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

Airbus: 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 loss 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, FAA, Transport Airplane Directorate, is authorized to 
approve alternative methods of compliance for this AD.

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


    Issued in Renton, Washington, on October 2, 2003.
Vi L. Lipski,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 03-25494 Filed 10-7-03; 8:45 am]
BILLING CODE 4910-13-P