[Federal Register Volume 63, Number 86 (Tuesday, May 5, 1998)]
[Proposed Rules]
[Pages 24760-24762]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-11889]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-18-AD]
RIN 2120-AA64


Airworthiness Directives; Airbus Model A320 Series Airplanes

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 A320 series 
airplanes. This proposal would require repetitive inspections to detect 
fatigue cracking of the front spar vertical stringers on the wings; and 
repair, if necessary. This proposal also provides for an optional 
terminating action for the repetitive inspections. This proposal is 
prompted by issuance of mandatory continuing airworthiness information 
by a foreign civil airworthiness authority. The actions specified by 
the proposed AD are intended to detect and correct fatigue cracking of 
the front spar vertical stringers on the wings, which could result in 
reduced structural integrity of the airframe.

DATES: Comments must be received by June 4, 1998.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 98-NM-18-AD, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056. Comments may be inspected at this location 
between 9:00 a.m. and 3:00 p.m., Monday through Friday, except Federal 
holidays.
    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: Norman B. Martenson, Manager, 
International Branch, ANM-116, FAA, Transport Airplane Directorate, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 
227-2110; 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 notice may be changed in 
light of the comments received.
    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 notice must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 98-NM-18-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. 98-NM-18-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 A320 series airplanes. The 
DGAC advises that, during full-scale fatigue testing on a Model A320 
test article, fatigue cracking occurred at 116,151 simulated flights on 
the front vertical stringer on the wing at frame 36. Such fatigue 
cracking, if not detected and corrected in a timely manner, could 
result in reduced structural integrity of the airframe.

Explanation of Relevant Service Information

    Airbus has issued Service Bulletin A320-57-1016, Revision 1, dated 
December 6, 1995, which describes procedures for repetitive eddy 
current

[[Page 24761]]

inspections to detect fatigue cracking of the front spar vertical 
stringers on the wings.
    In addition, Airbus has issued Service Bulletin A320-57-1017, 
Revision 01, dated March 17, 1997, which describes procedures for 
modification of the front spar vertical stringers on the wings. The 
modification includes the installation of new shims and new fasteners 
on the front spar vertical stringers on the wings. Accomplishment of 
this modification would eliminate the need for the repetitive 
inspections described in Airbus Service Bulletin A320-57-1016, Revision 
1.
    Accomplishment of the actions specified in these service bulletins 
is intended to adequately address the identified unsafe condition. The 
DGAC classified Airbus Service Bulletin A320-57-1016, Revision 1, dated 
December 6, 1995, as mandatory and issued French airworthiness 
directive 97-311-105(B), dated October 22, 1997, in order to assure the 
continued airworthiness of these airplanes in France.

FAA's Conclusions

    This airplane model is manufactured in France and is 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 inspections specified in Airbus Service Bulletin A320-57-1016, 
Revision 1, dated December 6, 1995, except as discussed below. This 
proposed AD also would provide for optional terminating action for the 
repetitive inspections.
    Operators should note that, in consonance with the findings of the 
DGAC, the FAA has determined that the repetitive inspections proposed 
by this AD can be allowed to continue in lieu of accomplishment of a 
terminating action. In making this determination, the FAA considers 
that, in this case, long-term continued operational safety will be 
adequately assured by accomplishing the repetitive inspections to 
detect fatigue cracking before it represents a hazard to the airplane.

Differences Between Proposed Rule and Service Bulletin

    Operators should note that, although Airbus Service Bulletin A320-
57-1016, Revision 1, dated December 6, 1995, specifies that the 
manufacturer may be contacted for disposition of certain repair 
conditions, this proposal would require the repair of those conditions 
to be accomplished in accordance with a method approved by either the 
FAA or the DGAC (or its delegated agent). In light of the type of 
repair that would be required to address the identified unsafe 
condition, and in consonance with existing bilateral airworthiness 
agreements, the FAA has determined that, for this proposed AD, a repair 
approved by either the FAA or the DGAC would be acceptable for 
compliance with this proposed AD.

Differences Between Proposed Rule and Foreign AD

    Operators should note that, unlike the procedures described in 
French airworthiness directive 97-311-105(B), dated October 22, 1997, 
this proposed AD would not permit further flight if fatigue cracks are 
detected on the front spar vertical stringers of the wings. The FAA has 
determined that, because of the safety implications and consequences 
associated with such fatigue cracking, any subject front spar vertical 
stringer that is found to be cracked must be repaired prior to further 
flight in accordance with a method approved by the FAA or the DGAC (or 
its delegated agent).

Cost Impact

    The FAA estimates that 16 airplanes of U.S. registry would be 
affected by this proposed AD. It would take approximately 2 work hours 
per airplane to accomplish the proposed inspection, at an average labor 
rate of $60 per work hour. Based on these figures, the cost impact of 
the inspection proposed by this AD on U.S. operators is estimated to be 
$1,920, or $120 per airplane, per inspection cycle.
    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.
    Should an operator elect to accomplish the optional terminating 
modification, rather than continue the repetitive inspections, it would 
require approximately 6 work hours to accomplish it, at an average 
labor rate of $60 per work hour. Required parts would cost 
approximately $700 per airplane. Based on these figures, the cost 
impact of the optional terminating modification proposed by this AD on 
U.S. operators is estimated to be $1,060 per airplane.

Regulatory Impact

    The regulations proposed herein would not have substantial direct 
effects 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, in 
accordance with Executive Order 12612, it is determined that this 
proposal would not have sufficient federalism implications to warrant 
the preparation of a Federalism Assessment.
    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 Industrie: Docket 98-NM-18-AD.

    Applicability: Model A320 series airplanes on which Airbus 
Modification 21290 (reference Airbus Service Bulletin A320-57-

[[Page 24762]]

1017, Revision 01, dated March 17, 1997) has not been installed, 
certificated in any category.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
otherwise modified, altered, or repaired in the area subject to the 
requirements of this AD. For airplanes that have been modified, 
altered, or repaired so that the performance of the requirements of 
this AD is affected, the owner/operator must request approval for an 
alternative method of compliance in accordance with paragraph (c) of 
this AD. The request should include an assessment of the effect of 
the modification, alteration, or repair on the unsafe condition 
addressed by this AD; and, if the unsafe condition has not been 
eliminated, the request should include specific proposed actions to 
address it.

    Compliance: Required as indicated, unless accomplished 
previously.
    To detect and correct fatigue cracking of the front spar 
vertical stringers on the wings, which could result in reduced 
structural integrity of the airframe, accomplish the following:
    (a) Prior to the accumulation of 24,000 total flight cycles, or 
within 60 days after the effective date of this AD, whichever occurs 
later: Perform an eddy current inspection to detect fatigue cracking 
of the front spar vertical stringers on the wings, in accordance 
with Airbus Service Bulletin A320-57-1016, Revision 1, dated 
December 6, 1995.
    (1) If no crack is detected, repeat the eddy current inspection 
thereafter at intervals not to exceed 14,000 flight cycles.
    (2) If any crack is detected, prior to further flight, repair in 
accordance with a method approved by the Manager, International 
Branch, ANM-116, FAA, Transport Airplane Directorate; or the 
Direction Generale de l'Aviation Civile (or its delegated agent). 
Thereafter, repeat the eddy current inspection at intervals not to 
exceed 14,000 flight cycles.
    (b) Modification of the front spar vertical stringers on the 
wings, in accordance with Airbus Service Bulletin A320-57-1017, 
Revision 01, dated March 17, 1997, constitutes terminating action 
for the repetitive inspection requirements of this AD.
    (c) An alternative method of compliance or adjustment of the 
compliance time that provides an acceptable level of safety may be 
used if approved by the Manager, International Branch, ANM-116. 
Operators shall submit their requests through an appropriate FAA 
Principal Maintenance Inspector, who may add comments and then send 
it to the Manager, International Branch, ANM-116.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the International Branch, ANM-116.

    (d) Special flight permits may be issued in accordance with 
sections 21.197 and 21.199 of the Federal Aviation Regulations (14 
CFR 21.197 and 21.199) to operate the airplane to a location where 
the requirements of this AD can be accomplished.

    Note 3: The subject of this AD is addressed in French 
airworthiness directive 97-311-105(B), dated October 22, 1997.

    Issued in Renton, Washington, on April 29, 1998.
John J. Hickey,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 98-11889 Filed 5-4-98; 8:45 am]
BILLING CODE 4910-13-U