[Federal Register Volume 62, Number 84 (Thursday, May 1, 1997)]
[Proposed Rules]
[Pages 23697-23699]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-11332]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 96-NM-170-AD]
RIN 2120-AA64


Airworthiness Directives; Airbus Model A300-600 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 A300-600 
series airplanes. This proposal would require repetitive inspections to 
detect fatigue cracking in the left and right wings in the area where 
the top skin attaches to the center spar; and repair or modification of 
this area, if necessary. This proposal is prompted by a report from the 
manufacturer indicating that, during full-scale fatigue testing of the 
airframe, fatigue cracking was detected in this area. The actions 
specified by the proposed AD are intended to detect and correct this 
cracking, which could reduce the residual strength of the top skin of 
the wings, and consequently affect the structural integrity of the 
airframe.

DATES: Comments must be received by June 12, 1997.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 96-NM-170-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: Charles Huber, Aerospace Engineer, 
Standardization Branch, ANM-113, FAA, Transport Airplane Directorate, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206) 
227-2589; fax (206) 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 96-NM-170-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-103, Attention: Rules 
Docket No. 96-NM-170-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, has notified the FAA that an unsafe 
condition may exist on certain Airbus Model A300-600 series airplanes. 
The DGAC advises that it has received a report from the manufacturer 
indicating that, during full-scale fatigue testing of the airframe, 
fatigue cracking was detected in an area of the wing where the top skin 
attaches to the center spar between ribs 1 and 7. This cracking 
originated in clearance fit fastener holes of joints between the skin 
and the center

[[Page 23698]]

spar, and was detected between 33,000 and 49,000 simulated flights.
    Initially, it was thought that this cracking was limited to a few 
airplanes. The manufacturer, however, has found that cracking is more 
widespread, and is apparently caused by shear stresses resulting from 
loads on the landing gear.
    This fatigue cracking, if not detected and corrected, could reduce 
the residual strength of the top skin of the wings, and consequently 
affect the structural integrity of the airframe.

Explanation of Relevant Service Information

    Airbus has issued Service Bulletin A300-57-6044, Revision 2, dated 
September 6, 1995, which describes procedures for conducting repetitive 
inspections to detect fatigue cracking in the left and right wings in 
the area where the top skin attaches to the center spar between ribs 1 
and 7; and repair or modification of this area, if necessary.
    The modification (Airbus Modification 10089) entails reinforcement 
of this area and is intended to prevent cracking. If that modification 
has not been installed prior to the initial inspection, operators must 
inspect using either a detailed visual inspection or a high frequency 
eddy current (HFEC) technique to detect fatigue cracking, and repair, 
if necessary. Should cracking exceed 75 mm per rib bay, however, Airbus 
recommends the installation of the modification. If Airbus Modification 
10089 has been installed prior to the initial inspection, operators are 
to conduct a low frequency eddy current inspection to detect fatigue 
cracking of the inboard and rear edges of the top skin reinforcing 
plate.
    The Airbus service bulletin references Airbus Service Bulletin 
A300-57-6041, Revision 4, dated November 16, 1995, as an additional 
source of service information for installing Airbus Modification 10089.
    The DGAC classified Airbus Service Bulletin A300-57-6044 as 
mandatory and issued French airworthiness directive (C/N) 95-086-180(B) 
R1, dated December 6, 1995, 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 repetitive 
inspections to detect fatigue cracking in the left and right wings in 
the area where the top skin attaches to the center spar between ribs 1 
and 7; and repair or modification of this area, if necessary.
    Repair of cracking found on airplanes on which Airbus Modification 
10089 has been accomplished would be required to be accomplished in 
accordance with a method approved by the FAA. Other actions would be 
required to be accomplished in accordance with Airbus Service Bulletin 
A300-57-6044, described previously.

Cost Impact

    The FAA estimates that 35 Airbus Model A300-600 series airplanes of 
U.S. registry would be affected by this proposed AD.
    For airplanes on which Airbus Modification 10089 has not been 
installed, it would take approximately 2 hours to accomplish each 
detailed visual inspection or 3 hours to accomplish each HFEC 
inspection. The average labor rate is $60 per work hour.
    Based on these figures, the cost impact of each proposed inspection 
on U.S. operators is estimated to be either $120 or $180 per airplane, 
depending on the type of inspection conducted.
    For airplanes on which Airbus Modification 10089 has been 
installed, it would take approximately 3 hours to accomplish each low 
frequency eddy current inspection.
    The average labor rate is $60 per work hour. Based on these 
figures, the cost impact of each proposed inspection on U.S. operators 
is estimated to be $180 per airplane.
    The cost impact figures discussed above are 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.

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: Docket 96-NM-170-AD.

    Applicability: Model A300-600 series airplanes, on which Airbus 
Modification 10160 has not been installed during production; 
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

[[Page 23699]]

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 in the left and right 
wings in the area where the top skin attaches to the center spar, 
which could reduce the residual strength of this skin, and 
consequently affect the structural integrity of the airframe, 
accomplish the following:
    (a) For airplanes on which Airbus Modification 10089 has not 
been installed: Prior to the accumulation of 18,000 total landings, 
or within 1,500 landings after the effective date of this AD, 
whichever occurs later, conduct either a detailed visual inspection 
or a high frequency eddy current (HFEC) inspection to detect fatigue 
cracking in the left and right wings in the area where the top skin 
attaches to the center spar between ribs 1 and 7, in accordance with 
Airbus Service Bulletin A300-57-6044, Revision 2, dated September 6, 
1995.
    (1) If no cracking is detected, conduct repetitive inspections 
thereafter at the following intervals:
    (i) If the immediately preceding inspection was conducted using 
detailed visual techniques, conduct the next inspection within 5,000 
landings.
    (ii) If the immediately preceding inspection was conducted using 
HFEC techniques, conduct the next inspection within 9,500 landings.
    (2) If any cracking is detected or suspected during any detailed 
visual inspection required by paragraph (a), (a)(1), or (a)(3)(i) of 
this AD, prior to further flight, confirm this finding and the 
length of this cracking by conducting a HFEC inspection, in 
accordance with the service bulletin. If no cracking is confirmed 
during the HFEC inspection, accomplish the repetitive inspection 
required by paragraph (a)(1)(ii) of this AD at the time specified in 
that paragraph.
    (3) If any cracking is detected or confirmed during any HFEC 
inspection required by paragraph (a), (a)(1), or (a)(2) of this AD:
    (i) If the cracking is 75 mm or less per rib bay, prior to 
further flight, repair in accordance with the service bulletin. 
Thereafter, conduct repetitive detailed visual inspections of the 
repaired area at intervals not to exceed 50 landings, in accordance 
with the service bulletin.
    (ii) If the cracking exceeds 75 mm per rib bay, prior to further 
flight, install Airbus Modification 10089, in accordance with the 
service bulletin. Thereafter, conduct a low frequency eddy current 
inspection in accordance with the requirements of paragraph (b) of 
this AD.

    Note 2: The Airbus service bulletin references Airbus Service 
Bulletin A300-57-6041, Revision 4, dated November 16, 1995, as an 
additional source of service information for installing Airbus 
Modification 10089.

    (b) For airplanes on which Airbus Modification 10089 has been 
installed: Prior to the accumulation of 22,000 total landings after 
this modification has been installed, or within 1,500 landings after 
the effective date of this AD, whichever occurs later, conduct a low 
frequency eddy current inspection to detect fatigue cracking in the 
inboard and rear edges of the top skin reinforcing plates, in 
accordance with Airbus Service Bulletin A300-57-6044, Revision 2, 
dated September 6, 1995.
    (1) If no cracking is detected, repeat this inspection 
thereafter at intervals not to exceed 11,000 landings.
    (2) If any cracking is detected, prior to further flight, repair 
in accordance with a method approved by the Manager, Standardization 
Branch, ANM-113, FAA, Transport Airplane Directorate. Thereafter, 
repeat this inspection at intervals not to exceed 11,000 landings.
    (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, Standardization Branch, ANM-113. 
Operators shall submit their requests through an appropriate FAA 
Principal Maintenance Inspector, who may add comments and then send 
it to the Manager, Standardization Branch, ANM-113.

    Note 3: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Standardization Branch, ANM-113.

    (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.

    Issued in Renton, Washington, on April 25, 1997.
Neil D. Schalekamp,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 97-11332 Filed 4-30-97; 8:45 am]
BILLING CODE 4910-13-U