[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
