Airworthiness Directives; Airbus Model A320 Series Airplanes

[Federal Register Volume 63, Number 173 (Tuesday, September 8, 1998)]
[Rules and Regulations]
[Pages 47423-47425]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-23738]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-18-AD; Amendment 39-10742; AD 98-18-26]
RIN 2120-AA64


Airworthiness Directives; Airbus Model A320 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to certain Airbus Model A320 series airplanes, that requires 
repetitive inspections to detect fatigue cracking of the front spar 
vertical stringers on the wings; and repair, if necessary. This 
amendment also provides for an optional terminating action for the 
repetitive inspections. This amendment is prompted by issuance of 
mandatory continuing airworthiness information by a foreign civil 
airworthiness authority. The actions specified by this 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: Effective October 13, 1998.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of October 13, 1998.

ADDRESSES: The service information referenced in this AD may be 
obtained from Airbus Industrie, 1 Rond Point Maurice Bellonte, 31707 
Blagnac Cedex, France. This information may be examined at the Federal 
Aviation Administration (FAA), Transport Airplane Directorate, Rules 
Docket, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of 
the Federal Register, 800 North Capitol Street, NW., suite 700, 
Washington, DC.

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: 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 A320 series 
airplanes was published in the Federal Register on May 5, 1998 (63 FR 
24760). That action proposed to require repetitive inspections to 
detect fatigue cracking of the front spar vertical stringers on the 
wings; and repair, if necessary. That action also proposed to provide 
for an optional terminating action for the repetitive inspections.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received.

Request To Allow Flight With Known Cracks

    One commenter, the manufacturer, requests that the proposed AD be 
revised to allow operators to continue operation of an unrepaired 
airplane following detection of cracks, utilizing the follow-on 
inspections and conditions described in Airbus Service Bulletin A320-
57-1016, Revision 1, dated December 6, 1995. The commenter states that 
the follow-on inspection intervals are based on fatigue test results 
and calculations of the crack propagation rate, depending on the crack 
length. The commenter also states that the structure of the Airbus 
Model A320 series airplane is classified as damage tolerant. 
Additionally, the commenter notes that the inspection program specified 
in the service bulletin was developed in order to prevent the need for 
extensive repairs of the aircraft.
    The FAA does not concur. It is the FAA's policy to require repair 
of known cracks prior to further flight, except in certain cases of 
unusual need, as

[[Page 47424]]

discussed below. This policy is based on the fact that such damaged 
airplanes do not conform to the FAA certificated type design, and 
therefore, are not airworthy until a properly approved repair is 
incorporated. While recognizing that repair deferrals may be necessary 
at times, the FAA policy is intended to minimize adverse human factors 
relating to the lack of reliability of long-term repetitive 
inspections, which may reduce the safety of the type certificated 
design if such repair deferrals are practiced routinely.
    As noted above, the FAA's policy regarding flight with known cracks 
does allow deferral of repairs in certain cases, if there is an unusual 
need for a temporary deferral. Unusual needs include such circumstances 
as legitimate difficulty in acquiring parts to accomplish repairs. 
Under such conditions, the FAA may allow a temporary deferral of the 
repair, subject to a stringent inspection program acceptable to the 
FAA. The FAA acknowledges that the manufacturer has specified 
inspection intervals that are intended to allow continued operation 
with known cracks, and to prevent the need for extensive repairs. 
However, since the FAA is not aware of any unusual need for repair 
deferral in regard to this AD, the FAA has not evaluated these 
inspection intervals.
    Additionally, the FAA policy applies to airplanes certificated to 
damage tolerance evaluation regulations as well as those not so 
certificated. Therefore, the commenter's statement that ``the Airbus 
Model A320 airplane structure is classified as damage tolerant'' is not 
relevant to the application of the FAA's policy in this regard.
    The FAA considers the compliance times in this AD to be adequate to 
allow operators to acquire parts to have on hand in the event that a 
crack is detected during inspection. Therefore, the FAA has determined 
that, due to the safety implications and consequences associated with 
such cracking, any subject bottom flange or fastener hole that is found 
to be cracked must be repaired or modified prior to further flight. No 
change to the final rule is necessary.

Request To Revise Service Bulletin Dates

    One commenter supports the intent of the proposed AD, but requests 
that it be revised to reflect the correct issuance date for Revision 1 
of Airbus Service Bulletins A320-57-1016 and A320-57-1017. The 
commenter states that the correct issuance date for both of these 
service bulletins is September 3, 1991. The FAA does not concur. The 
original version of these service bulletins is dated September 3, 1991, 
rather than Revision 1. Therefore, the FAA finds that no change to the 
final rule is necessary.

Conclusion

    After careful review of the available data, including the comments 
noted above, the FAA has determined that air safety and the public 
interest require the adoption of the rule as proposed.

Cost Impact

    The FAA estimates that 16 airplanes of U.S. registry will be 
affected by this AD, that it will take approximately 2 work hours per 
airplane to accomplish the required inspection, and that the average 
labor rate is $60 per work hour. Based on these figures, the cost 
impact of the inspection required 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 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 provided by this AD on 
U.S. operators is estimated to be $1,060

Regulatory Impact

    The regulations adopted herein will 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 final 
rule does not have sufficient federalism implications to warrant the 
preparation of a Federalism Assessment.
    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.

List of 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.


Sec. 39.13  [Amended]

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

98-18-26  Airbus Industrie: Amendment 39-10742. Docket 98-NM-18-AD.

    Applicability: Model A320 series airplanes on which Airbus 
Modification 21290 (reference Airbus Service Bulletin A320-57-1017, 
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.

[[Page 47425]]

    (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.
    (e) The inspections shall be done in accordance with Airbus 
Service Bulletin A320-57-1016, Revision 1, dated December 6, 1995, 
which contains the following list of effective pages:

------------------------------------------------------------------------
                                   Revision level       Date shown  on
           Page No.                 shown on page            page
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1-4, 7........................  1...................  Dec. 6, 1995
5-6, 8-13.....................  Original............  Sept. 3, 1991
------------------------------------------------------------------------

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

    (f) This amendment becomes effective on October 13, 1998.

    Issued in Renton, Washington, on August 28, 1998.
Vi L. Lipski, Acting Manager,
Transport Airplane Directorate,Aircraft Certification Service.
[FR Doc. 98-23738 Filed 9-4-98; 8:45 am]
BILLING CODE 4910-13-P

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