[Federal Register Volume 79, Number 141 (Wednesday, July 23, 2014)]
[Proposed Rules]
[Pages 42710-42716]
[FR Doc No: 2014-17324]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2014-0454; Directorate Identifier 2013-NM-138-AD]
RIN 2120-AA64

Airworthiness Directives; the Boeing Company Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: We propose to supersede Airworthiness Directive (AD) 2002-07-
08, which applies to certain The Boeing Company Model 737 airplanes. AD
2002-07-08 currently requires repetitive inspections for cracking of
the lower skin at the lower row of fasteners in the lap joints of the
fuselage; repair of any cracking found; modification of the fuselage
lap joints at certain locations, which terminates the repetitive
inspections of the modified areas; and replacement of a certain
preventive modification with an improved modification. Since we issued
AD 2002-07-08, we have determined that adjacent stringers and window
frames have cracked in locations outside the inspection areas addressed
by AD 2002-07-08. This proposed AD would add repetitive inspections for
cracking at certain window corner fastener holes, a preventive
modification, post-repair/alteration and butt joint repetitive
inspections, and repair if necessary. We are proposing this AD to
detect and correct fatigue cracking of the fuselage lap joints, which
could result in reduced structural integrity and sudden decompression
of the airplane.

DATES: We must receive comments on this proposed AD by September 8,
2014.

ADDRESSES: You may send comments, using the procedures found in 14 CFR
11.43 and 11.45, by any of the following methods:
     Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the instructions for submitting comments.

     Fax:<PHONE_NUMBER>.
     Mail: U.S. Department of Transportation, Docket
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New
Jersey Avenue SE., Washington, DC 20590.
     Hand Delivery: Deliver to Mail address above between 9
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
    For service information identified in this proposed AD, contact
Boeing Commercial Airplanes, Attention: Data & Services Management,
P.O. Box 3707, MC 2H-65, Seattle, WA 98124-2207; telephone 206-544-
5000, extension 1; fax<PHONE_NUMBER>; Internet https://www.myboeingfleet.com. You may view this referenced service information
at the FAA, Transport Airplane Directorate, 1601 Lind Avenue SW.,
Renton, WA. For information on the availability of this material at the
FAA, call<PHONE_NUMBER>.

Examining the AD Docket

    You may examine the AD docket on the Internet at http://www.regulations.gov by searching for and locating Docket No. FAA-2014-
0454; or in person at the Docket Management Facility between 9 a.m. and
5 p.m., Monday through Friday, except Federal holidays. The AD docket
contains this proposed AD, the regulatory evaluation, any comments
received, and other information. The street address for the Docket
Office (phone:<PHONE_NUMBER>) is in the ADDRESSES section. Comments will
be available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT: Wayne Lockett, Aerospace Engineer,
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office
(ACO), 1601 Lind Avenue SW., Renton, WA 98057-3356; phone: 425-917-
6447; fax:<PHONE_NUMBER>; email<EMAIL_ADDRESS>
SUPPLEMENTARY INFORMATION:

Comments Invited

    We invite you to send any written relevant data, views, or
arguments about this proposed AD. Send your comments to an address
listed under the ADDRESSES section. Include ``Docket No. FAA-2014-0454;
Directorate Identifier 2013-NM-138-AD'' at the beginning of your
comments. We specifically invite comments on the overall regulatory,
economic, environmental, and energy aspects of this proposed AD. We
will consider all comments received by the closing date and may amend
this proposed AD because of those comments.
    We will post all comments we receive, without change, to http://www.regulations.gov, including any personal information you provide. We
will also post a report summarizing each substantive verbal contact we
receive about this proposed AD.

Discussion

    On April 2, 2002, we issued AD 2002-07-08, Amendment 39-12702 (67
FR 17917, April 12, 2002), for certain the Boeing Company Model 737
airplanes. AD 2002-07-08 requires repetitive inspections for cracking
of the lower skin at the lower row of fasteners in the lap joints of
the fuselage; repair of any cracking found; modification of the
fuselage lap joints at certain locations, which terminates the
repetitive inspections of the modified areas; and replacement of a
certain preventive modification with an improved modification. AD 2002-
07-08 resulted from the FAA's determination that, in light of
additional crack findings, certain modifications of the fuselage lap
joints did not provide an acceptable level of safety. We issued AD
2002-07-08 to detect and correct cracking of the fuselage lap joints,
which could result in sudden decompression of the airplane.

Widespread Fatigue Damage

    Structural fatigue damage is progressive. It begins as minute
cracks, and those cracks grow under the action of repeated stresses.
This can happen because of normal operational conditions and design
attributes, or because of isolated situations or incidents such as
material defects, poor fabrication quality, or corrosion pits, dings,
or scratches. Fatigue damage can occur locally, in small areas or
structural design details, or globally. Global fatigue damage is
general degradation of large areas of structure with similar structural
details and stress levels. Multiple-site damage is global damage that
occurs in a large structural element such as a single rivet line of a
lap splice joining two large skin panels. Global damage can also occur
in multiple elements such as adjacent frames or stringers. Multiple-
site-damage and multiple-element-damage cracks are typically too small
initially to be reliably detected with normal inspection methods.
Without intervention, these cracks will grow, and eventually compromise
the structural integrity of the airplane, in a condition known as
widespread fatigue damage (WFD). As an airplane ages, WFD will likely
occur, and will certainly occur if the airplane is operated long enough
without any intervention.
    The FAA's WFD final rule (75 FR 69746, November 15, 2010) became
effective on January 14, 2011. The WFD rule requires certain actions to
prevent structural failure due to WFD throughout the operational life
of certain existing transport category airplanes and all of these
airplanes that will be certificated in the future. For existing and
future airplanes subject to the WFD rule, the rule requires that design
approval holders (DAHs) establish a limit of validity (LOV) of the
engineering data that support the structural maintenance program.
Operators affected by the WFD rule may not fly an airplane beyond its
LOV, unless an extended LOV is approved.
    The WFD rule (75 FR 69746, November 15, 2010) does not require
identifying and developing maintenance actions if the DAHs can show
that such actions are not necessary to prevent WFD before the airplane
reaches the LOV. Many LOVs, however, do depend on accomplishment of
future maintenance actions. As stated in the WFD rule, any maintenance
actions necessary to reach the LOV will be mandated by airworthiness
directives through separate rulemaking actions.
    In the context of WFD, this action is necessary to enable DAHs to
propose LOVs that allow operators the longest operational lives for
their airplanes, and still ensure that WFD will not occur. This
approach allows for an implementation strategy that provides
flexibility to DAHs in determining the timing of service information
development (with FAA approval), while providing operators with
certainty regarding the LOV applicable to their airplanes.

Actions Since AD 2002-07-08, Amendment 39-12702 (67 FR 17917, April 12,
2002), Was Issued

    Since we issued AD 2002-07-08, Amendment 39-12702 (67 FR 17917,
April 12, 2002), we have determined that adjacent stringers and window
frames have cracked in locations outside the inspection areas addressed
by AD 2002-07-08. More extensive inspections over a larger area are
therefore necessary.

Relevant Service Information

    We reviewed Boeing Service Bulletin 737-53A1177, Revision 7, dated
June 14, 2013, which describes procedures for certain new actions that
were not included in previous revisions of this service information.
These new actions include repetitive inspections for cracking at
certain window corner

fastener holes, a preventive modification, and post-repair/alteration
and butt joint repetitive inspections and repair if necessary. For
information on the procedures and compliance times, see this service
information at http://www.regulations.gov by searching for Docket No.
FAA-2014-0454.

FAA's Determination

    We are proposing this AD because we evaluated all the relevant
information and determined the unsafe condition described previously is
likely to exist or develop in other products of the same type design.

Proposed AD Requirements

    This proposed AD would retain certain requirements of AD 2002-07-
08, Amendment 39-12702 (67 FR 17917, April 12, 2002). This proposed AD
would also require accomplishing the actions specified in the service
information described previously, except as discussed under
``Difference Between this Proposed AD and the Service Information.''

Related ADs

    Boeing has identified a group of airplanes affected by AD 2002-07-
08, Amendment 39-12702 (67 FR 17917, April 12, 2002), that did not
specify crown lap splice inspections until they reached their
modification threshold of 50,000 total flight cycles. This was
determined to be a safety concern. We have issued AD 2013-09-01,
Amendment 39-17442 (78 FR 27001, May 9, 2013), to require these crown
lap splice inspections for the affected airplanes, and this proposed AD
would remove the overlapping requirements (paragraphs (a), (b), (c),
and (f)) from AD 2002-07-08. Those crown lap splice inspections are
described in Boeing Service Bulletin 737-53A1255, Revision 2, dated
August 7, 2012.
    AD 2013-09-01, Amendment 39-17442 (78 FR 27001, May 9, 2013),
applies to certain Model 737 airplanes and requires various repetitive
inspections for cracking of certain fuselage crown lap joints. The lap
joint modification/repair specified in this proposed AD would terminate
certain inspections of AD 2013-09-01.

Difference Between the Proposed AD and the Service Information

    Boeing Service Bulletin 737-53A1177, Revision 7, dated June 14,
2013, specifies to contact the manufacturer for instructions for
certain actions, but this proposed AD would require accomplishment of
those actions in one of the following ways:
     In accordance with a method that we approve; or
     Using data that meet the certification basis of the
airplane, and that have been approved by the Boeing Commercial
Airplanes Organization Designation Authorization (ODA) whom we have
authorized to make those findings.
    This proposed AD will address only Model 737 airplanes with line
numbers 292 through 2565. Model 737 airplanes with line numbers 1
through 291 have been addressed in AD 2003-23-03, Amendment 39-13367
(68 FR 64980, November 18, 2003).

Additional Changes to AD 2002-07-08, Amendment 39-12702 (67 FR 17917,
April 12, 2002)

    Boeing Commercial Airplanes has received an ODA. This proposed AD
would delegate the authority to approve an alternative method of
compliance for any repair or modification required by this proposed AD
to the Boeing Commercial Airplanes ODA rather than a Designated
Engineering Representative (DER).

Explanation of a Certain Compliance Time

    The compliance time for the preventive modification specified in
this proposed AD for addressing WFD was established to ensure that
discrepant structure is modified before WFD develops in airplanes.
Standard inspection techniques cannot be relied on to detect WFD before
it becomes a hazard to flight. We will not grant any extensions of the
compliance time to complete any AD-mandated service bulletin related to
WFD without extensive new data that would substantiate and clearly
warrant such an extension.

Costs of Compliance

    We estimate that this proposed AD affects 247 airplanes of U.S.
registry. We estimate the following costs to comply with this proposed
AD:

                                        Estimated Costs--Required Actions
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                                                                                Cost on U.S.
            Action                    Labor cost             Parts cost       Cost per product      operators
----------------------------------------------------------------------------------------------------------------
Retained lap joint              4,650 work-hours x     Up to $204,000.......  $599,250........  $95,280,750
 modification.                   $85 per hour =                                                  (estimated 159
                                 $395,250.                                                       airplanes).
Retained lap joint inspection.  90 work-hours x $85    $0...................  $7,650 per        $1,889,550 per
                                 per hour = $7,650                             inspection        inspection
                                 per inspection cycle.                         cycle.            cycle.
Retained post-NACA inspection.  110 work-hours x $85   $0...................  $9,350 per        $308,550 per
                                 per hour = $9,350                             inspection        inspection
                                 per inspection cycle.                         cycle.            cycle
                                                                                (estimated 33
                                                                                airplanes).
Retained window corner          36 work-hours x $85    $0...................  $3,060 per        $755,820 per
 inspection.                     per hour = $3,060                             inspection        inspection
                                 per inspection cycle.                         cycle.            cycle.
New window corner inspection..  108 work-hours x $85   $0...................  $9,180 per        $2,267,460 per
                                 per hour = $9,180                             inspection        inspection
                                 per inspection cycle.                         cycle.            cycle.
----------------------------------------------------------------------------------------------------------------

                                        Estimated Costs--Optional Actions
----------------------------------------------------------------------------------------------------------------
                                                                                Cost per
                Action                                Labor cost                   Parts cost        product
----------------------------------------------------------------------------------------------------------------
New preventive modification..........  134 work-hours x $85 per hour = $11,390              $0          $11,390
----------------------------------------------------------------------------------------------------------------

    We estimate the following costs to do any necessary corrective
actions that would be required based on the results of the proposed
inspection. We have no way of determining the number of aircraft that
might need these corrective actions:

                                               On-Condition Costs
----------------------------------------------------------------------------------------------------------------
                  Action                                Labor cost                 Parts cost    Cost per corner
----------------------------------------------------------------------------------------------------------------
Window corner repair, per corner..........  9 work-hours x $85 per hour = $765           (\1\)             $765
----------------------------------------------------------------------------------------------------------------
\1\ Parts fabricated by operator; cost unknown.

    The cost estimate figures discussed above are based on assumptions
that no operator has yet accomplished any of the actions required by
this proposed AD, and that no operator would accomplish those actions
in the future if this proposed AD were not adopted. However, we have
been advised that the lap joint modification has already been installed
on some affected airplanes. Therefore, based on the current number of
U.S.-registered airplanes below the threshold of 50,000 total flight
cycles, the future economic cost impact of this proposed AD on U.S.
operators is expected to be less than the cost impact figure indicated
above.

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 proposed 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 proposed AD would not have federalism
implications under Executive Order 13132. This proposed AD would 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 the 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),
    (3) Will not affect intrastate aviation in Alaska, and
    (4) 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.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by
reference, Safety.

The Proposed Amendment

    Accordingly, under the authority delegated to me by the
Administrator, the FAA proposes to amend 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 removing Airworthiness Directive (AD)
2002-07-08, Amendment 39-12702 (67 FR 17917, April 12, 2002), and
adding the following new AD:

The Boeing Company: Docket No. FAA-2014-0454; Directorate Identifier
2013-NM-138-AD.

(a) Comments Due Date

    The FAA must receive comments on this AD action by September 8,
2014.

(b) Affected ADs

    This AD replaces AD 2002-07-08, Amendment 39-12702 (67 FR 17917,
April 12, 2002). Certain provisions of this AD affect certain
requirements of AD 2013-09-01, Amendment 39-17442 (78 FR 27001, May
9, 2013).

(c) Applicability

    This AD applies to The Boeing Company Model 737-200, -200C, -
300, -400, and -500 series airplanes, certificated in any category,
line numbers 292 through 2565 inclusive.

(d) Subject

    Air Transport Association (ATA) of America Code 53, Fuselage.

(e) Unsafe Condition

    This AD was prompted by an evaluation by the design approval
holder (DAH) indicating that certain fuselage lap joints are subject
to widespread fatigue damage (WFD). We are issuing this AD to detect
and correct fatigue cracking of the fuselage lap joints, which could
result in reduced structural integrity and sudden decompression of
the airplane.

(f) Compliance

    Comply with this AD within the compliance times specified,
unless already done.

(g) Retained Lap Joint Modification (Repair)--Crown Areas

    This paragraph restates the actions required by paragraph (g) of
AD 2002-07-08, Amendment 39-12702 (67 FR 17917, April 12, 2002),
with revised service information. Except as provided by paragraph
(h) of this AD: Install the lap joint repair as specified in Part
1.E.1. (``Compliance'') of Boeing Service Bulletin 737-53A1177,
Revision 4, dated September 2, 1999; Boeing Service Bulletin 737-
53A1177, Revision 5, dated February 15, 2001; or Boeing Service
Bulletin 737-53A1177, Revision 6, dated May 31, 2001; per PART III
or IV (``Lap Joint Repair''), as applicable; or Boeing Service
Bulletin 737-53A1177, Revision 7, dated June 14, 2013; per PART III,
IV, VI, or VII (``Lap Joint Modification (Repair)''), as applicable,
of the Accomplishment Instructions of the applicable service
bulletin; at the time specified in paragraph (g)(1), (g)(2), (g)(3),
(g)(4), or (g)(5) of this AD, as applicable. Accomplishment of this
repair terminates the repetitive inspections required by paragraph
(j) of this AD. As of the effective date of this AD, only Boeing
Service Bulletin 737-53A1177, Revision 7, dated June 14, 2013, may
be used to do the actions required by this paragraph. A lap splice
modification (repair) done in accordance with the Accomplishment
Instructions of Boeing Service Bulletin 737-53A1177, Revision 7,
dated June 14, 2013, terminates the inspections required by
paragraphs (g) and (i) of AD 2013-09-01, Amendment 39-17442 (78 FR
27001, May 9, 2013), for the modified (repaired) area only.
    (1) For airplanes that have accumulated 70,000 total flight
cycles or more as of May 17, 2002 (the effective date of AD 2002-07-
08, Amendment 39-12702 (67 FR 17917, April 12, 2002)): Within 600
flight cycles after May 17, 2002, do the lap joint repair.
    (2) For airplanes that have accumulated 65,000 total flight
cycles or more, but fewer than 70,000 total flight cycles as of May
17, 2002 (the effective date of AD 2002-07-08, Amendment 39-12702
(67 FR 17917, April 12, 2002)): Do the repair at the later of the
times specified in paragraphs (g)(2)(i) and (g)(2)(ii) of this AD.
    (i) Before the accumulation of 70,000 total flight cycles.

    (ii) Within 600 flight cycles after May 17, 2002 (the effective
date of AD 2002-07-08, Amendment 39-12702 (67 FR 17917, April 12,
2002)).
    (3) For airplanes that have accumulated 45,000 total flight
cycles or more, but fewer than 65,000 total flight cycles as of May
17, 2002 (the effective date of AD 2002-07-08, Amendment 39-12702
(67 FR 17917, April 12, 2002)): Within 5,000 flight cycles after May
17, 2002.
    (4) For airplanes that have accumulated less than 45,000 total
flight cycles as of May 17, 2002 (the effective date of AD 2002-07-
08, Amendment 39-12702 (67 FR 17917, April 12, 2002)): Before the
accumulation of 50,000 total flight cycles.
    (5) Notwithstanding the times specified in paragraphs (g)(1),
(g)(2), (g)(3), and (g)(4) of this AD, for airplanes on which the
``Preventive Change'' (NACA modification) has been accomplished per
PART III of the Accomplishment Instructions of Boeing Alert Service
Bulletin 737-53A1177, Revision 1, dated September 19, 1996; Revision
2, dated July 24, 1997; or Revision 3, dated September 18, 1997:
Within 18,000 flight cycles after accomplishment of the NACA
modification.

(h) Retained Lap Joint Modification for Certain Airplanes

    This paragraph restates the requirements of paragraph (h) of AD
2002-07-08, Amendment 39-12702 (67 FR 17917, April 12, 2002), with
revised service information and revised airplane groups.
    (1) For airplanes identified as Groups 3 and 5 in Boeing Service
Bulletin 737-53A1177, Revision 6, dated May 31, 2001: Install the
lap joint repair at stringers 4R and 10R, as specified in Part
1.E.1. (``Compliance'') of Boeing Service Bulletin 737-53A1177,
Revision 6, dated May 31, 2001, at the time specified in paragraph
(g)(1), (g)(2), (g)(3), (g)(4), or (g)(5) of this AD, as applicable,
using a method approved in accordance with the procedures specified
in paragraph (t) of this AD.
    (2) For airplanes identified in Groups 6, 7, and 8 in Boeing
Service Bulletin 737-53A1177, Revision 7, dated June 14, 2013:
Install the lap joint repair at stringers 4R and 10R, in accordance
with the Accomplishment Instructions of Boeing Service Bulletin 737-
53A1177, Revision 7, dated June 14, 2013, at the time specified in
paragraph (g)(1), (g)(2), (g)(3), (g)(4), or (g)(5) of this AD, as
applicable, unless previously accomplished as specified in paragraph
(h)(1) of this AD.

(i) Retained Repetitive Low Frequency Eddy Current (LFEC) Inspections--
Outside Crown Areas

    This paragraph restates the actions required by paragraph (i) of
AD 2002-07-08, Amendment 39-12702 (67 FR 17917, April 12, 2002),
with revised service information. Before the accumulation of 70,000
total flight cycles, or within 2,500 flight cycles after May 17,
2002 (the effective date of AD 2002-07-08), whichever comes later:
Do an LFEC inspection to find cracking of the lap joints of the
fuselage, as specified in Part 1.E.2. (``Compliance'') of Boeing
Service Bulletin 737-53A1177, Revision 6, dated May 31, 2001; or
Boeing Service Bulletin 737-53A1177, Revision 7, dated June 14,
2013; and as identified in Figures 2 through 6 of the Accomplishment
Instructions of Boeing Service Bulletin 737-53A1177, Revision 6,
dated May 31, 2001; or as identified in Figures 50 through 64 of the
Accomplishment Instructions of Boeing Service Bulletin 737-53A1177,
Revision 7, dated June 14, 2013. Do the inspection per Boeing
Service Bulletin 737-53A1177, Revision 6, dated May 31, 2001; or
Boeing Service Bulletin 737-53A1177, Revision 7, dated June 14,
2013. As of the effective date of this AD, only Boeing Service
Bulletin 737-53A1177, Revision 7, dated June 14, 2013, may be used
to do the actions required by this paragraph. Repeat the inspection
after that at intervals not to exceed 5,000 flight cycles.

(j) Retained Post-NACA Modification Inspections--Crown Areas

    This paragraph restates the actions required by paragraph (j) of
AD 2002-07-08, Amendment 39-12702 (67 FR 17917, April 12, 2002),
with revised service information. For airplanes that have the
``Preventive Change'' (NACA modification) of the crown lap joint
stringers (``Crown Laps'') done per PART III of the Accomplishment
Instructions of Boeing Alert Service Bulletin 737-53A1177, Revision
1, dated September 19, 1996; Boeing Service Bulletin 737-53A1177,
Revision 2, dated July 24, 1997; or Boeing Service Bulletin 737-
53A1177, Revision 3, dated September 18, 1997: Within 12,000 flight
cycles after accomplishment of the NACA modification, or within 750
flight cycles after May 17, 2002 (the effective date of AD 2002-07-
08), whichever is later, do either an external (Figure 8) or
internal (Figure 9) LFEC inspection to find cracking and corrosion
as specified in Part 1.E.4.a. (``Compliance'') of Boeing Service
Bulletin 737-53A1177, Revision 6, dated May 31, 2001; or Boeing
Service Bulletin 737-53A1177, Revision 7, dated June 14, 2013; per
PART I (``Inspection'') of the Accomplishment Instructions of Boeing
Service Bulletin 737-53A1177, Revision 6, dated May 31, 2001; or
Boeing Service Bulletin 737-53A1177, Revision 7, dated June 14,
2013. As of the effective date of this AD, only Boeing Service
Bulletin 737-53A1177, Revision 7, dated June 14, 2013, may be used
to do the actions required by this paragraph.
    (1) If the external inspection is done: Repeat the inspection
after that at intervals not to exceed 1,500 flight cycles until
accomplishment of the lap joint repair required by paragraph (g) of
this AD.
    (2) If the internal inspection is done: Repeat the inspection
after that at intervals not to exceed 4,500 flight cycles until
accomplishment of the lap joint repair required by paragraph (g) of
this AD.

(k) Retained Post-NACA Modification Inspections--Outside Crown Areas

    This paragraph restates the actions required by paragraph (k) of
AD 2002-07-08, Amendment 39-12702 (67 FR 17917, April 12, 2002),
with revised service information. For airplanes that have the
``Preventive Change'' (NACA modification) outside the crown areas
done per PART III of the Accomplishment Instructions of Boeing Alert
Service Bulletin 737-53A1177, Revision 1, dated September 19, 1996;
Boeing Service Bulletin 737-53A1177, Revision 2, dated July 24,
1997; or Boeing Service Bulletin 737-53A1177, Revision 3, dated
September 18, 1997: Before the accumulation of 20,000 flight cycles
after accomplishment of the NACA modification, or within 750 flight
cycles after May 17, 2002 (the effective date of AD 2002-07-08),
whichever is later, do either an external (Figure 8) or internal
(Figure 9) LFEC inspection to find cracking and corrosion as
specified in Part 1.E.4.b. (``Compliance'') of Boeing Service
Bulletin 737-53A1177, Revision 6, dated May 31, 2001; or Boeing
Service Bulletin 737-53A1177, Revision 7, dated June 14, 2013; per
PART I (``Inspection'') of the Accomplishment Instructions of Boeing
Service Bulletin 737-53A1177, Revision 6, dated May 31, 2001; or
Boeing Service Bulletin 737-53A1177, Revision 7, dated June 14,
2013. As of the effective date of this AD, only Boeing Service
Bulletin 737-53A1177, Revision 7, dated June 14, 2013, may be used
to do the actions required by this paragraph.
    (1) If the external inspection is done: Repeat the external
inspection after that at intervals not to exceed 1,500 flight
cycles.
    (2) If the internal inspection is done: Repeat the internal
inspection after that at intervals not to exceed 4,500 flight
cycles.

(l) Retained Modification of Tear Strap Splice Straps

    This paragraph restates the actions required by paragraph (l) of
AD 2002-07-08, Amendment 39-12702 (67 FR 17917, April 12, 2002),
with revised service information. For airplanes that have the ``lap
joint repair,'' as specified in Part IV of the Accomplishment
Instructions of Boeing Alert Service Bulletin 737-53A1177, Revision
2, dated July 24, 1997, or Revision 3, dated September 18, 1997:
Within 45,000 flight cycles after accomplishment of this lap joint
repair, modify the splice straps per Figures 10, 11, and 12 of the
Accomplishment Instructions of Boeing Service Bulletin 737-53A1177,
Revision 6, dated May 31, 2001; or Boeing Service Bulletin 737-
53A1177, Revision 7, dated June 14, 2013. As of the effective date
of this AD, only Boeing Service Bulletin 737-53A1177, Revision 7,
dated June 14, 2013, may be used to do the actions required by this
paragraph.

(m) Retained Follow-On LFEC Inspections

    This paragraph restates the actions required by paragraph (m) of
AD 2002-07-08, Amendment 39-12702 (67 FR 17917, April 12, 2002),
with revised service information. Within 45,000 flight cycles after
accomplishment of the lap joint repair required by paragraph (g) or
(h) of this AD, as applicable: Do either an external or internal
(Figure 9) LFEC inspection as specified in Part 1.E.7.
(``Compliance'') of Boeing Service Bulletin 737-53A1177, Revision 6,
dated May 31, 2001; or Boeing Service Bulletin 737-53A1177, Revision
7, dated June 14, 2013; to find cracking of the lap joint repair,
per PART I (``Inspection'') of

the Accomplishment Instructions of Boeing Service Bulletin 737-
53A1177, Revision 6, dated May 31, 2001; or Boeing Service Bulletin
737-53A1177, Revision 7, dated June 14, 2013. As of the effective
date of this AD, only Boeing Service Bulletin 737-53A1177, Revision
7, dated June 14, 2013, may be used to do the actions required by
this paragraph. Repeat the inspection after that at intervals not to
exceed 2,800 flight cycles.

(n) Retained Repetitive High Frequency Eddy Current (HFEC)
Inspections--Window Corners

    This paragraph restates the actions required by paragraph (n) of
AD 2002-07-08, Amendment 39-12702 (67 FR 17917, April 12, 2002),
with revised service information. For airplanes having line numbers
520 through 2565 inclusive: Before the accumulation of 50,000 total
flight cycles, or within 2,250 flight cycles after May 17, 2002 (the
effective date of AD 2002-07-08), whichever comes later, do an HFEC
inspection to find cracking as specified in Part 1.E.10
(``Compliance'') of Boeing Service Bulletin 737-53A1177, Revision 6,
dated May 31, 2001, or Boeing Service Bulletin 737-53A1177, Revision
7, dated June 14, 2013; per PART V (``Window Corner Fastener Hole
Cracking, Inspection and Repair'') of the Accomplishment
Instructions of Boeing Service Bulletin 737-53A1177, Revision 6,
dated May 31, 2001; or Boeing Service Bulletin 737-53A1177, Revision
7, dated June 14, 2013. Repeat the inspection after that at
intervals not to exceed 4,500 flight cycles, until the initial
actions required by paragraph (p) of this AD have been done.
Accomplishment of the modification (which includes removing and
discarding fasteners, oversizing fastener holes, and installing
rivets or Hi-Lok fasteners, as applicable), per PART V of the
Accomplishment Instructions of Boeing Service Bulletin 737-53A1177,
Revision 5, dated February 15, 2001; or Boeing Service Bulletin 737-
53A1177, Revision 6, dated May 31, 2001; or Boeing Service Bulletin
737-53A1177, Revision 7, dated June 14, 2013; constitutes
terminating action for the inspections required by this paragraph.

(o) Retained Crack Repair

    This paragraph restates the actions required by paragraph (d) of
AD 2002-07-08, Amendment 39-12702 (67 FR 17917, April 12, 2002),
with revised service information. If any crack is found during any
inspection required by paragraph (i), (j), (k), (m), or (n) of this
AD: Before further flight, repair per PART II (``Crack Repair'') of
the Accomplishment Instructions of Boeing Service Bulletin 737-
53A1177, Revision 6, dated May 31, 2001; or Boeing Service Bulletin
737-53A1177, Revision 7, dated June 14, 2013; except as required by
paragraph (s)(2) of this AD. As of the effective date of this AD,
only Boeing Service Bulletin 737-53A1177, Revision 7, dated June 14,
2013, may be used to do the actions required by this paragraph.

(p) New Inspections, Repair, and Preventive Modification

    For airplanes identified as Groups 2 through 28 in Boeing
Service Bulletin 737-53A1177, Revision 7, dated June 14, 2013: At
the applicable times specified in tables 8, 9, 10, and 11 of
paragraph 1.E.10 of the Compliance section of Boeing Service
Bulletin 737-53A1177, Revision 7, dated June 14, 2013, except as
required by paragraph (s)(1) of this AD, do a surface HFEC
inspection for cracking at the applicable window corner fastener
holes, and do a preventive modification, as applicable, in
accordance with Part V of the Accomplishment Instructions of Boeing
Service Bulletin 737-53A1177, Revision 7, dated June 14, 2013,
except as required by paragraph (s)(2) of this AD. Repair any crack
found before further flight in accordance with Part V of the
Accomplishment Instructions of Boeing Service Bulletin 737-53A1177,
Revision 7, dated June 14, 2013, except as required by paragraph
(s)(2) of this AD. Repeat the applicable inspection thereafter at
the applicable times specified in tables 8, 9, 10, and 11 of
paragraph 1.E.10 of the Compliance section of Boeing Service
Bulletin 737-53A1177, Revision 7, dated June 14, 2013.
Accomplishment of the initial inspection specified in this paragraph
terminates the repetitive inspection requirements of paragraph (n)
of this AD. Accomplishment of the preventive modification specified
in this paragraph terminates the repetitive inspection requirements
of this paragraph for the applicable corner fastener locations
specified in Boeing Service Bulletin 737-53A1177, Revision 7, dated
June 14, 2013.

(q) Optional Terminating Action

    (1) Accomplishment of the actions specified in Part VIII or Part
IX, as applicable, of the Accomplishment Instructions of Boeing
Service Bulletin 737-53A1177, Revision 7, dated June 14, 2013,
terminates the repetitive inspections at the window corners
specified in paragraph (p) of this AD.
    (2) Replacement of the skin panel as specified in Part VIII or
Part IX, as applicable, of Boeing Service Bulletin 737-53A1177,
Revision 7, dated June 14, 2013, terminates the lap joint
modification required by paragraph (g) of this AD for the S-10 and
S-14 lap joints common to the replaced panel only.

(r) Post-Repair/Alteration Inspections and Repair

    For airplanes identified as Groups 2 through 28 in Boeing
Service Bulletin 737-53A1177, Revision 7, dated June 14, 2013:
Except as provided by paragraph (s)(1) of this AD, at the time
specified in tables 12, 13, 14, 15, 16, 17, and 18, as applicable,
of paragraph 1.E., ``Compliance,'' of Boeing Service Bulletin 737-
53A1177, Revision 7, dated June 14, 2013, do the applicable post-
repair and post-alteration inspections (including an internal HFEC
inspection, external surface inspection, surface inspection, and
internal surface HFEC inspections), and butt joint inspections
(including internal surface HFEC and detailed inspections) for
cracking at the applicable locations, in accordance with the
Accomplishment Instructions of Boeing Service Bulletin 737-53A1177,
Revision 7, dated June 14, 2013. Repair any crack before further
flight using a method approved in accordance with the procedures
specified in paragraph (t) of this AD. Repeat the applicable
inspections thereafter at the time specified in tables 12, 13, 14,
15, 16, 17, and 18, as applicable, of paragraph 1.E.,
``Compliance,'' of Boeing Service Bulletin 737-53A1177, Revision 7,
dated June 14, 2013.

(s) Exceptions to Service Information Specifications

    (1) Where Boeing Service Bulletin 737-53A1177, Revision 7, dated
June 14, 2013, specifies a compliance time ``after the Revision 7
date of this service bulletin,'' this AD requires compliance within
the specified compliance time after the effective date of this AD.
    (2) Where Boeing Service Bulletin 737-53A1177, Revision 6, dated
May 31, 2001; and Boeing Service Bulletin 737-53A1177, Revision 7,
dated June 14, 2013; specify to contact Boeing for certain
procedures: Do the specified actions before further flight using a
method approved in accordance with the procedures specified in
paragraph (t) of this AD.
    (3) Where Boeing Service Bulletin 737-53A1177, Revision 6, dated
May 31, 2001; and Boeing Service Bulletin 737-53A1177, Revision 7,
dated June 14, 2013; include the phrase ``or is Boeing or FAA
approved,'' this AD requires the ``Boeing Approval'' to be requested
in accordance with the procedures specified in paragraph (t) of this
AD.

(t) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, Seattle Aircraft Certification Office (ACO),
FAA, has the authority to approve AMOCs for this AD, if requested
using the procedures found in 14 CFR 39.19. In accordance with 14
CFR 39.19, send your request to your principal inspector or local
Flight Standards District Office, as appropriate. If sending
information directly to the manager of the ACO, send it to the
attention of the person identified in paragraph (u)(1) of this AD.
Information may be emailed to<EMAIL_ADDRESS>    (2) Before using any approved AMOC, notify your appropriate
principal inspector, or lacking a principal inspector, the manager
of the local flight standards district office/certificate holding
district office.
    (3) An AMOC that provides an acceptable level of safety may be
used for any repair required by this AD if it is approved by the
Boeing Commercial Airplanes Organization Designation Authorization
(ODA) that 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.
    (4) AMOCs approved for AD 2002-07-08, Amendment 39-12702 (67 FR
17917, April 12, 2002), are approved as AMOCs for the corresponding
provisions of this AD.

(u) Related Information

    (1) For more information about this AD, contact Wayne Lockett,
Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft
Certification Office (ACO), 1601 Lind Avenue SW., Renton, WA 98057-
3356; phone:<PHONE_NUMBER>; fax:<PHONE_NUMBER>; email:
<EMAIL_ADDRESS>    (2) For service information identified in this AD, contact
Boeing Commercial Airplanes, Attention: Data & Services Management,
P.O. Box 3707, MC 2H-65, Seattle, WA 98124-2207; telephone 206-544-
5000, extension 1; fax<PHONE_NUMBER>; Internet https://www.myboeingfleet.com. You may view this referenced service
information at the FAA, Transport Airplane Directorate, 1601 Lind
Avenue SW., Renton, WA. For information on the availability of this
material at the FAA, call<PHONE_NUMBER>.

    Issued in Renton, Washington, on July 13, 2014.
Jeffrey E. Duven,
Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 2014-17324 Filed 7-22-14; 8:45 am]
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