[Federal Register: September 27, 2005 (Volume 70, Number 186)]
[Rules and Regulations]
[Page 56358-56361]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr27se05-7]
[[Page 56358]]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2005-20356; Directorate Identifier 2004-NM-115-AD;
Amendment 39-14294; AD 2005-20-01]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 737-100, -200, -200C, -
300, -400, and -500 Series Airplanes
AGENCY: Federal Aviation Administration (FAA), Department of
Transportation (DOT).
ACTION: Final rule.
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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for all
Boeing Model 737-100, -200, -200C, -300, -400, and -500 series
airplanes. This AD requires repetitive inspections of the stiffeners at
left buttock line (LBL) and right buttock line (RBL) 6.15 for cracks;
and replacement of both stiffeners with new, improved stiffeners if any
stiffener is found cracked. This AD also allows replacement of both
stiffeners at LBL and RBL 6.15 with new, improved stiffeners, which
terminates the repetitive inspections. This AD is prompted by reports
of cracks in the stiffeners at LBL and RBL 6.15 on the rear spar of the
wing center section. We are issuing this AD to detect and correct
cracks in the stiffeners at LBL and RBL 6.15, which could result in
damage to the keel beam structure and consequently reduce the
capability of the airplane to sustain flight loads.
DATES: This AD becomes effective November 1, 2005.
The incorporation by reference of a certain publication listed in
the AD is approved by the Director of the Federal Register as of
November 1, 2005.
ADDRESSES: You may examine the AD docket on the Internet at http://dms.dot.gov
or in person at the Docket Management Facility, U.S.
Department of Transportation, 400 Seventh Street, SW., Nassif Building,
room PL-401, Washington, DC.
Contact Boeing Commercial Airplanes, PO Box 3707, Seattle,
Washington 98124-2207, for service information identified in this AD.
FOR FURTHER INFORMATION CONTACT: Nancy Marsh, Aerospace Engineer,
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office,
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425)
917-6440; fax (425) 917-6590.
Examining the Docket
You may examine the AD docket on the Internet at http://dms.dot.gov
or in person at the Docket Management Facility office between 9 a.m.
and 5 p.m., Monday through Friday, except Federal holidays. The Docket
Management Facility office (telephone (800) 647-5227) is located on the
plaza level of the Nassif Building at the street address stated in the
ADDRESSES section.
Discussion
The FAA issued a notice of proposed rulemaking (NPRM) to amend 14
CFR part 39 to include an AD that would apply to all Boeing Model 737-
100, -200, -200C, -300, -400, and -500 series airplanes. That NPRM was
published in the Federal Register on February 15, 2005 (70 FR 7693). (A
correction of the NPRM was published in the Federal Register on May 19,
2005 (70 FR 28988).) That NPRM proposed to require repetitive
inspections of the stiffeners at left buttock line (LBL) and right
buttock line (RBL) 6.15 for cracks; and replacement of both stiffeners
with new, improved stiffeners if any stiffener is found cracked. That
NPRM also proposed to allow replacement of both stiffeners at LBL and
RBL 6.15 with new, improved stiffeners, which would terminate the
repetitive inspections.
Comments
We provided the public the opportunity to participate in the
development of this AD. We have considered the comments that have been
submitted on the proposed AD.
Support for the Proposed AD
Two commenters support the proposed AD.
Request To Use Operator Equivalent Procedures
One commenter requests that we revise paragraph (h) of the proposed
AD to allow the use of FAA-approved, operator equivalent procedures for
draining and gaining access to the center fuel tanks. The commenter
states that Parts II and III of Boeing Alert Service Bulletin 737-
57A1269, Revision 1, dated September 16, 2004, contain work steps for
de-fueling and purging the center tanks. The commenter further states
that mandating how the fuel tanks are purged does not directly affect
the means of correcting the unsafe condition addressed in the proposed
AD.
We agree that the procedures specified in Parts II and III are
intended for gaining access to the center tanks. We also agree that
using an equivalent procedure to gain access would not adversely affect
the means of correcting the unsafe condition, which is to detect and
correct cracks in the stiffeners at LBL and RBL 6.15. Therefore, we
have revised the first sentence of paragraph (h) of this AD to require
accomplishing the applicable actions in Part IV through Part IX of the
service bulletin.
Request for Credit for Previous Inspections
One commenter requests that inspections performed in accordance
with Boeing All Operator Telex (AOT) M-7200-01-00426, dated February
19, 2001, be considered acceptable for compliance with the inspections
specified in paragraph (g) of the proposed AD. The commenter states
that both Boeing AOT M-7200-01-00426 and Boeing Alert Service Bulletin
737-57A1269, Revision 1, dated September 16, 2004, provide instructions
for doing a detailed inspection of the stiffeners at LBL and RBL 6.15
on the rear spar of the wing center section within the same compliance
time.
We agree that the detailed inspections specified in Boeing AOT M-
7200-01-00426 are acceptable for compliance with the corresponding
requirements of this AD. We have added a new paragraph (k) to this AD
to give credit and re-lettered the subsequent paragraphs accordingly.
Request To Use New Stiffeners of the Existing Type Design
Two commenters request that we revise paragraph (h) of the proposed
AD to add the option of replacing a cracked stiffener with a new
stiffener of the existing type design (made from 7075-T6511 aluminum
extrusion). One commenter states that since we have determined a
repetitive inspection interval of 4,500 flight cycles provides an
adequate level of safety for detecting cracks in the existing
stiffeners, then replacement with new stiffeners of the existing type
design should also provide an adequate level of safety if the
repetitive inspections are continued. Although there is an ample supply
of new stiffeners of the existing type design available, both
commenters are concerned that there is an insufficient supply of new,
improved stiffeners (made from 2024-T351 aluminum alloy plate) to
comply with the proposed replacements.
We do not agree. The manufacturer has confirmed that there is a
sufficient supply of new, improved stiffeners available to comply with
this AD. Therefore, no change to this AD is necessary in this regard.
[[Page 56359]]
Request To Replace a Stiffener, Only if Cracked
Two commenters request that we revise paragraph (h) of the proposed
AD to state that, if only one of the two stiffeners is found cracked,
operators would be required to replace only the cracked stiffener
instead of both stiffeners. As justification, the first commenter
states that it frequently finds only one cracked stiffener during
inspections of the stiffeners at LBL and RBL 6.15. Both commenters
believe that the proposed AD should allow the option of replacing only
the cracked stiffener provided that the repetitive inspections for
cracking are continued until both stiffeners are eventually replaced.
The second commenter supports this change because replacing both
stiffeners requires additional labor and material. The commenter also
states that the aggressive initial inspection threshold will force
operators to inspect affected airplanes outside of a heavy maintenance
visit. The commenter asserts that the additional impact of replacing
both stiffeners will strain available resources.
We do not agree because the new, improved stiffeners are much more
rigid than the stiffeners of the existing type design. Replacing only
one of the two stiffeners will lead to changes in the loading of the
structure and premature fatigue of the new, improved stiffener.
However, we acknowledge that replacing a cracked stiffener with a new
stiffener of the existing type design will not adversely affect the
relative stiffness of the two keel beam stiffeners, since they would be
the same type design. If service information containing repair
instructions and subsequent inspection requirements for replacing a
cracked stiffener with a new stiffener of the existing type design is
developed, under the provisions of paragraph (l) of this AD, we may
consider requests for approval of an AMOC. Sufficient data must be
submitted to substantiate that such a design change would provide an
acceptable level of safety. Therefore, no change to this AD is
necessary in this regard.
Request To Allow Temporary Repairs
Three commenters request that we revise the proposed AD to allow
operators to make temporary repairs until cracked stiffeners can be
replaced. One commenter suggests adding an interim repair plan to the
proposed AD to give operators time to schedule the terminating action
(replacement of cracked stiffeners with new, improved stiffeners). The
commenter proposes that an interim repair plan could consist of stop-
drilling small cracks where possible and reducing the repetitive
inspection intervals to monitor crack growth, until the terminating
action could be accomplished. The commenter is concerned it will not be
able to comply with the requirements of the proposed AD because of the
short initial inspection threshold and number of affected airplanes in
its fleet.
The second commenter states that repairs done in accordance with
Boeing AOT M-7200-01-00426, dated February 19, 2001, and Repair Sketch
LOR-760 will take less time than replacement of the stiffeners,
especially since most of its affected airplanes will be inspected
outside of a heavy maintenance visit. The third commenter asks if we
would consider the two temporary repairs, which do not require access
into the center tank, as an AMOC to the proposed AD.
We partially agree. The FAA is working with the manufacturer to
establish appropriate inspection and replacement requirements for this
interim repair. Once this evaluation is concluded we may, under the
provisions of paragraph (l) of this AD, we approve the subject interim
repairs as an AMOC. We do not consider that delaying this final rule is
warranted.
Request To Revise Compliance Time
One commenter requests that we extend the compliance time of the
initial inspection, from 180 days to 15 months for airplanes that have
accumulated less than 30,000 total flight cycles, to allow affected
operators to perform the inspection during a regularly scheduled
maintenance interval. The proposed AD reported that cracked stiffeners
were found on two airplanes with over 40,000 total flight cycles and on
a third airplane with just over 20,000 total flight cycles. The
commenter believes that the data are not consistent enough to warrant a
short compliance time for airplanes that have accumulated fewer than
40,000 total flight cycles. To comply with the proposed AD, the
operator states that it would have to inspect more than 1 airplane per
week, since the proposed AD affects the majority of its fleet. The
operator also states that its operations would be negatively impacted
if several of its airplanes required the terminating action, estimated
at 250 work hours.
We do not agree with the commenter's request. The commenter
provides no technical justification for revising this inspection
interval. Furthermore, since issuing the proposed AD, we have received
numerous additional reports of cracked stiffeners. Eight of those
reports included airplanes that have accumulated fewer than 30,000
total flight cycles. We have determined that the compliance time, as
proposed, represents the maximum interval of time allowable for the
affected airplanes to continue to operate safely before the inspection
is accomplished.
Request To Revise ``Cost of Compliance''
One commenter estimates that the proposed inspection would take
about 4 work hours, not 1 work hour as we specified in the proposed AD.
We infer that the commenter would like us to revise the ``Cost of
Compliance'' section.
We do not agree, since the commenter has not provided justification
for the increase in work hours. Our cost estimate is based on
information that the manufacturer has provided to us, and we point out
that the cost impact figures discussed in AD rulemaking actions
represent only the time necessary to perform the specific actions
actually required by the AD. These figures typically do not include
incidental costs, such as the time required to gain access and close
up, planning time, or time necessitated by other administrative
actions. Therefore no change to this AD is necessary in this regard.
Explanation of Changes Made to This AD
We have simplified paragraph (h) of this AD by referring to the
``Alternative Methods of Compliance (AMOCs)'' paragraph of this AD for
repair methods. Also, we have revised the ``Alternative Methods of
Compliance (AMOCs)'' paragraph in this AD to clarify the delegation
authority for Authorized Representatives for the Boeing Commercial
Airplanes Delegation Option Authorization.
Conclusion
We have carefully reviewed the available data, including the
comments that have been submitted, and determined that air safety and
the public interest require adopting the AD with the changes described
previously. We have determined that these changes will neither increase
the economic burden on any operator nor increase the scope of the AD.
Costs of Compliance
This AD affects about 3,132 airplanes worldwide. The following
table provides the estimated costs, at an average labor rate of $65 per
hour, for U.S. operators to comply with this AD.
[[Page 56360]]
Estimated Costs
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Number of
U.S.-
Action Work hours Parts Cost per airplane registered Fleet cost
airplanes
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Inspection, per inspection cycle 1 None $65, per inspection 1,384 $89,960, per
cycle. inspection cycle.
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Authority for This Rulemaking
Title 49 of the United States Code specifies the FAA's authority to
issue rules on aviation safety. Subtitle I, Section 106, describes the
authority of the FAA Administrator. Subtitle VII, Aviation Programs,
describes in more detail the scope of the Agency's authority.
We are issuing this rulemaking under the authority described in
Subtitle VII, Part A, Subpart III, Section 44701, ``General
requirements.'' Under that section, Congress charges the FAA with
promoting safe flight of civil aircraft in air commerce by prescribing
regulations for practices, methods, and procedures the Administrator
finds necessary for safety in air commerce. This regulation is within
the scope of that authority because it addresses an unsafe condition
that is likely to exist or develop on products identified in this
rulemaking action.
Regulatory Findings
We have determined that this AD will not have federalism
implications under Executive Order 13132. This AD will not have a
substantial direct effect 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.
For the reasons discussed above, I certify that this AD:
(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.
We prepared a regulatory evaluation of the estimated costs to
comply with this AD. See the ADDRESSES section for a location to
examine the regulatory evaluation.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by
reference, Safety.
Adoption of the Amendment
0
Accordingly, under the authority delegated to me by the Administrator,
the FAA amends 14 CFR part 39 as follows:
PART 39--AIRWORTHINESS DIRECTIVES
0
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]
0
2. The FAA amends Sec. 39.13 by adding the following new airworthiness
directive (AD):
2005-20-01 Boeing: Amendment 39-14294. Docket No. FAA-2005-20356;
Directorate Identifier 2004-NM-115-AD.
Effective Date
(a) This AD becomes effective November 1, 2005.
Affected ADs
(b) None.
Applicability
(c) This AD applies to all Boeing Model 737-100, -200, -200C, -
300, -400, and -500 series airplanes, certificated in any category.
Unsafe Condition
(d) This AD was prompted by cracks in the stiffeners at left
buttock line (LBL) and right buttock line (RBL) 6.15 on the rear
spar of the wing center section. We are issuing this AD to detect
and correct cracks in the stiffeners at LBL and RBL 6.15, which
could result in damage to the keel beam structure and consequently
reduce the capability of the airplane to sustain flight loads.
Compliance
(e) You are responsible for having the actions required by this
AD performed within the compliance times specified, unless the
actions have already been done.
Service Bulletin Reference
(f) The term ``service bulletin,'' as used in this AD, means the
Accomplishment Instructions of Boeing Alert Service Bulletin 737-
57A1269, Revision 1, dated September 16, 2004.
Initial and Repetitive Inspections
(g) Before accumulating 15,000 total flight cycles, or within
180 days after the effective date of this AD, whichever occurs
later: Do a detailed inspection of the stiffeners at LBL and RBL
6.15 for cracks, in accordance with Part I of the service bulletin.
Thereafter at intervals not to exceed 4,500 flight cycles, repeat
the detailed inspection until the stiffeners at LBL and RBL 6.15
have been replaced with new, improved stiffeners, in accordance with
paragraph (h) or (i) of this AD.
Note 1: For the purposes of this AD, a detailed inspection is:
``An intensive examination of a specific item, installation, or
assembly to detect damage, failure, or irregularity. Available
lighting is normally supplemented with a direct source of good
lighting at an intensity deemed appropriate. Inspection aids such as
mirror, magnifying lenses, etc., may be necessary. Surface cleaning
and elaborate procedures may be required.''
Replacement of Cracked Stiffeners
(h) If any crack is found during any inspection required by this
AD, before further flight, replace both stiffeners with new,
improved stiffeners by doing all of the applicable actions in Part
IV through Part IX, as applicable, of the service bulletin; except
where the service bulletin specifies to contact Boeing for
appropriate action: Before further flight, repair using a method
approved in accordance with the procedures specified in paragraph
(l) of this AD. Accomplishing the replacement terminates the
repetitive inspections required by paragraph (g) of this AD.
Optional Terminating Action
(i) Replacement of both stiffeners at LBL and RBL 6.15 with new,
improved stiffeners in accordance with paragraph (h) of this AD
terminates the repetitive inspections required by this AD.
Credit for Previous Service Bulletin
(j) The actions done before the effective date of this AD in
accordance with Boeing Alert Service Bulletin 737-57A1269, dated
December 4, 2003, are acceptable for compliance with the
corresponding actions required by this AD.
Credit for Previous Inspections
(k) Inspections done before the effective date of this AD in
accordance with Boeing All Operator Telex M-7200-01-00426, dated
February 19, 2001, are acceptable for compliance with the
requirements of paragraph (g) of this AD.
Alternative Methods of Compliance (AMOCs)
(l)(1) The Manager, Seattle Aircraft Certification Office (ACO),
FAA, has the authority to approve AMOCs for this AD, if requested in
accordance with the procedures found in 14 CFR 39.19.
(2) An AMOC that provides an acceptable level of safety may be
used for any repair
[[Page 56361]]
required by this AD, if it is approved by an Authorized
Representative for the Boeing Commercial Airplanes Delegation Option
Authorization Organization who has been authorized by the Manager,
Seattle ACO, to make those findings. For a repair method to be
approved, the repair must meet the certification basis of the
airplane, and the approval must specifically refer to this AD.
Material Incorporated by Reference
(m) You must use Boeing Alert Service Bulletin 737-57A1269,
Revision 1, dated September 16, 2004, to perform the actions that
are required by this AD, unless the AD specifies otherwise. The
Director of the Federal Register approved the incorporation by
reference of this document in accordance with 5 U.S.C. 552(a) and 1
CFR part 51. Contact Boeing Commercial Airplanes, P.O. Box 3707,
Seattle, Washington 98124-2207, for a copy of this service
information. You may review copies at the Docket Management
Facility, U.S. Department of Transportation, 400 Seventh Street,
SW., room PL-401, Nassif Building, Washington, DC; on the Internet
at http://dms.dot.gov; or at the National Archives and Records
Administration (NARA). For information on the availability of this
material at the NARA, call (202) 741-6030, or go to http://www.archives.gov/federal-register/cfr/ibr-locations.html
.
Issued in Renton, Washington, on September 16, 2005.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 05-19144 Filed 9-26-05; 8:45 am]
BILLING CODE 4910-13-P