[Federal Register Volume 64, Number 178 (Wednesday, September 15, 1999)]
[Rules and Regulations]
[Pages 49966-49969]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-23476]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-249-AD; Amendment 39-11313; AD 99-19-26]
RIN 2120-AA64


Airworthiness Directives; Airbus Model A300 and A300-600 Series 
Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment supersedes an existing airworthiness directive 
(AD), applicable to certain Airbus Model A300 and A300-600 series 
airplanes, that currently requires inspections to detect cracks in Gear 
Rib 5 of the main landing gear (MLG) attachment fittings at the lower 
flange, and repair, if necessary. This amendment establishes repetitive 
inspection intervals for certain inspections required by the existing 
AD. This amendment also adds a requirement to modify Gear Rib 5 of the 
MLG attachment fittings, which constitutes 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 prevent fatigue cracking of the MLG attachment fittings, which could 
result in reduced structural integrity of the airplane.

DATES: Effective October 20, 1999.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of October 20, 1999.

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) by superseding AD 98-03-06, 
amendment 39-10298 (63 FR 5224, February 2, 1998), which is applicable 
to certain Airbus Model A300 and A300-600 series airplanes, was 
published in the Federal Register on November 23, 1998 (63 FR 64661). 
The action proposed to continue to require inspections to detect cracks 
in Gear Rib 5 of the main landing gear (MLG) attachment fittings at the 
lower flange, and repair, if necessary. That action also proposed to 
establish repetitive inspection intervals for certain inspections 
required by the existing AD. That action also proposed to add a

[[Page 49967]]

requirement to modify Gear Rib 5 of the MLG attachment fittings, which 
constitutes terminating action for the repetitive inspections.

Comments Received

    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received.

Support for the Proposal

    One commenter, an operator, expresses no objection to the 
inspections or modification required by the proposed AD.

Request to Remove Requirement for Terminating Modification

    One commenter, the manufacturer, states that, according to the 
damage-tolerance methodology of design and evaluation, safety is 
maintained by adequate repetitive inspections because crack initiation 
and propagation can be anticipated with sufficient precision to allow 
inspection programs to safely detect and repair metal fatigue or other 
structural damage before safety is affected (without accomplishing 
modifications). Therefore, the commenter does not see the need to 
mandate structural modifications in general, or in the specific case of 
this proposed AD.
    The commenter notes that if inspection results are considered in 
specific cases to be unreliable due to access difficulty or human 
factor considerations, the Airworthiness Assurance Working Group (AAWG) 
of the Aviation Rulemaking Advisory Committee has established three 
major criteria for determining when a terminating modification should 
be mandated. The commenter further states that these criteria were 
developed industry-wide in the context of general aging aircraft 
activities, but do apply in general to aircraft structures and provide 
adequate guidance for such a determination. The commenter requests that 
general guidelines for mandating structural modifications be 
established in line with the criteria already set forth by the AAWG.
    The FAA does not agree that the damage tolerance methodology, and 
the continuance of long-term repetitive inspections, provide adequate 
continued operational safety in many cases. Following a structure-
related accident in 1988, FAA policy transitioned to a more stringent 
assessment of whether modifications should be mandated, and worked with 
the AAWG in development of criteria for such evaluation. The FAA 
considers this policy necessary to counteract the reduced efficacy of 
inspection resulting from the increased likelihood of damage as 
airplanes age.
    The FAA agrees that general guidelines should be established that 
are in line with the criteria set forth by the AAWG. In the case of 
this AD, the FAA did utilize the AAWG criteria as a general guideline 
in making the decision to require accomplishment of the modification. 
The FAA infers that the commenter is requesting that the requirement to 
accomplish the terminating modification be removed from the proposed 
AD. The FAA does not concur in this case. In making the determination 
that the terminating modification should be mandated, several factors 
were considered, as discussed below.
     Consequence of Failure: As noted by the Direction Generale 
de l'Aviation Civile (DGAC), which is the airworthiness authority for 
France, in its corresponding airworthiness directive, the propagation 
of cracks in the area of concern could affect the structural integrity 
of the airplane. Although not stated specifically in the proposed AD, 
the FAA considers that such reduced integrity could cause permanent 
deformation of the surrounding structure that could lead to fuel leaks. 
Further, cracking of Gear Rib 5 of the main landing gear (MLG) 
attachment fitting could precipitate failure of the fitting, which 
could possibly lead to failure of the MLG during landing, rupture of 
the fuel tank, and fire. These factors led the FAA to determine that a 
significant unsafe condition exists.
     Probability of Occurrence: The referenced Airbus service 
bulletins document eleven in-service occurrences of cracking, detected 
on airplanes which had accumulated between 20,959 and 29,023 total 
flight cycles. The likelihood of cracking therefore appears high for 
airplanes on which 21,000 total flight cycles or more have been 
accumulated. Since a number of airplanes exist today in the world with 
this amount of service, the FAA proposed 21,000 total flight cycles as 
the compliance time for the modification. Additionally, due to the age 
of affected airplanes, the FAA considers it possible that other 
adjacent damage may exist, which could aggravate the seriousness of the 
cracking.
     Access/Inspection Difficulty: The FAA judges the 
difficulty of both access to the inspection area and accomplishment of 
the inspection itself to be above average. Cracks are not evident 
without a directed inspection, and approximately 3 work hours are 
required to gain access to the inspection area. Additionally, some 
cracks found during inspections were already of a substantial length, 
indicating that such cracking may have existed without detection for 
some time. Therefore, the FAA concludes that there is a certain level 
of difficulty in continued access and accomplishment of this 
inspection.
    In consideration of the factors described above, and using the 
general criteria established by the AAWG, the FAA has determined that 
accomplishment of the terminating modification is justified.

Request To Revise Applicability

    One commenter requests that the applicability of the proposed AD be 
revised to exclude those airplanes on which Airbus Modification 11912 
has been installed in production. The commenter notes that this 
production modification is equivalent to the retrofit solution 
described in Airbus Service Bulletins A300-57-6088 and A300-57-0235, 
both dated August 5, 1998, which are referenced in the proposed AD as 
appropriate terminating action for the repetitive inspection 
requirements of this AD. The FAA concurs that airplanes on which the 
production modification or the retrofit modification has been installed 
may be excluded from the requirements of this AD, and has revised the 
applicability of the final rule accordingly.

Service Bulletin Revisions

    Airbus has issued Service Bulletins A300-57-6088, Revision 01 (for 
Model A300-600 series airplanes), and A300-57-0235, Revision 01 (for 
Model A300 series airplanes), both dated February 1, 1999. These 
revisions clarify work procedures, add Figures, and update the cost and 
materials information. The FAA has determined that these later 
revisions of the service bulletins are substantially equivalent to the 
original issue of the bulletins. Therefore, the FAA has revised 
paragraph (d) of the final rule to cite Revision 01 of the applicable 
service bulletins as the appropriate source of service information. A 
Note 3 also has been added to the final rule to provide credit for 
operators who may have accomplished the modification in accordance with 
the previously cited service bulletins prior to the effective date of 
this AD.

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 with the changes previously 
described. The FAA has

[[Page 49968]]

determined that these changes will neither increase the economic burden 
on any operator nor increase the scope of the AD.

Cost Impact

    There are approximately 164 airplanes of U.S. registry that will be 
affected by this AD.
    The inspection currently required by AD 98-03-06, and retained in 
this new AD, takes approximately 6 work hours per airplane to 
accomplish, at an average labor rate of $60 per work hour. Based on 
these figures, the cost impact of the currently required inspection on 
U.S. operators is estimated to be $59,040, or $360 per airplane, per 
inspection cycle.
    The modification required by this new AD will take approximately 62 
work hours per airplane to accomplish, at an average labor rate of $60 
per work hour. Required parts will cost approximately $10,270 per 
airplane. Based on these figures, the cost impact of the new actions 
required by this AD on U.S. operators is estimated to be $2,294,360, or 
$13,990 per airplane.
    The cost impact figures discussed above are 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.

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 removing amendment 39-10298 (63 FR 
5224, February 2, 1998), and by adding a new airworthiness directive 
(AD), amendment 39-11313, to read as follows:

99-19-26  Airbus Industrie: Amendment 39-11313. Docket 98-NM-249-AD. 
Supersedes AD 98-03-06, Amendment 39-10298.

    Applicability: Model A300 series airplanes, as listed in Airbus 
Service Bulletin A300-57-0234, Revision 01, dated March 11, 1998; 
and Model A300-600 series airplanes, as listed in Airbus Service 
Bulletin A300-57-6087, Revision 01, dated March 11, 1998; except 
airplanes on which Airbus Modification 11912 has been installed in 
production, or on which Airbus Modification 11932 has been 
accomplished; 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 (e) 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 prevent fatigue cracking of the main landing gear (MLG) 
attachment fittings, which could result in reduced structural 
integrity of the airplane, accomplish the following:

Restatement of Requirements of AD 98-03-06

Inspections and Repair

    (a) For Model A300 series airplanes that have accumulated more 
than 27,000 flight cycles as of March 9, 1998 (the effective date of 
AD 98-03-06, amendment 39-10298): Except as provided by paragraph 
(b) of this AD, within 40 flight cycles after March 9, 1998, perform 
a detailed visual inspection to detect cracks in Gear Rib 5 of the 
MLG attachment fittings at the lower flange, in accordance with 
Airbus Service Bulletin A300-57-0234, Revision 01, dated March 11, 
1998. Thereafter, repeat the inspection at intervals not to exceed 
40 flight cycles, until the initial inspections required by 
paragraph (b) are accomplished.
    (b) For all airplanes: Perform a detailed visual and a high 
frequency eddy current (HFEC) inspection to detect cracks in Gear 
Rib 5 of the MLG attachment fittings at the lower flange, in 
accordance with Airbus Service Bulletin A300-57-6087, Revision 01, 
dated March 11, 1998 (for Model A300-600 series airplanes); or A300-
57-0234, Revision 01, dated March 11, 1998 (for Model A300 series 
airplanes); as applicable; at the time specified in paragraph (b)(1) 
or (b)(2) of this AD, as applicable. Repeat the inspections 
thereafter at intervals not to exceed 1,500 flight cycles. 
Accomplishment of the inspections required by this paragraph 
terminates the inspections required by paragraph (a) of this AD.
    (1) For airplanes that have accumulated 20,000 or more total 
flight cycles as of March 9, 1998: Inspect within 500 flight cycles 
after March 9, 1998.
    (2) For airplanes that have accumulated less than 20,000 total 
flight cycles as of March 9, 1998: Inspect prior to the accumulation 
of 18,000 total flight cycles, or within 1,500 flight cycles after 
March 9, 1998, whichever occurs later.

    Note 2: Accomplishment of the initial detailed visual and HFEC 
inspections in accordance with Airbus Service Bulletin A300-57A0234 
or A300-57A6057, both dated August 5, 1997, as applicable, is 
considered acceptable for compliance with the initial inspections 
required by paragraph (a) or (b) of this AD.

    (c) If any crack is detected during any inspection required by 
this AD, 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).

New Requirements of This AD

Terminating Modification

    (d) Prior to the accumulation of 21,000 total flight cycles, or 
within 2 years after the effective date of this AD, whichever occurs 
later: Modify Gear Rib 5 of the MLG attachment fittings at the lower 
flange in accordance with Airbus Service Bulletin A300-57-6088, 
Revision 01, including Appendix 01 (for Model A300-600 series 
airplanes), or A300-57-0235, Revision 01, including Appendix 01 (for 
Model A300 series airplanes), all dated February 1, 1999, as 
applicable. Accomplishment of this modification constitutes 
terminating action for the repetitive inspection requirements of 
this AD.

    Note 3: Accomplishment of the modification required by paragraph 
(d) of

[[Page 49969]]

this AD prior to the effective date of this AD in accordance with 
Airbus Service Bulletin A300-57-6088 or A300-57-0235, both dated 
August 5, 1998; as applicable; is acceptable for compliance with the 
requirements of that paragraph.

Alternative Methods of Compliance

    (e) 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 4: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the International Branch, ANM-116.

Special Flight Permits

    (f) 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.

Incorporation by Reference

    (g) Except as provided by paragraph (c) of this AD, the actions 
shall be done in accordance with Airbus Service Bulletin A300-57-
6087, Revision 01, dated March 11, 1998; Airbus Service Bulletin 
A300-57-0234, Revision 01, dated March 11, 1998; Airbus Service 
Bulletin A300-57-6088, Revision 01, dated February 1, 1999, 
including Appendix 01, dated February 1, 1999; and Airbus Service 
Bulletin A300-57-0235, Revision 01, dated February 1, 1999, 
including Appendix 01, dated February 1, 1999; as applicable. 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 5: The subject of this AD is addressed in French 
Airworthiness directive 98-151-247(B), dated April 8, 1998.

    (h) This amendment becomes effective on October 20, 1999.

    Issued in Renton, Washington, on September 2, 1999.
Dorenda D. Baker,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-23476 Filed 9-14-99; 8:45 am]
BILLING CODE 4910-13-P