```

[Federal Register Volume 79, Number 141 (Wednesday, July 23, 2014)]
[Proposed Rules]
[Pages 42710-42716]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[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).

-----------------------------------------------------------------------

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.

[[Page 42711]]

     Fax: 202-493-2251.
     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 206-766-5680; 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 425-227-1221.

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: 800-647-5527) 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: 425-917-6590; email: wayne.lockett@faa.gov.

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

[[Page 42712]]

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
----------------------------------------------------------------------------------------------------------------
                                                                                                  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:

[[Page 42713]]

                                               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.

[[Page 42714]]

    (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

[[Page 42715]]

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: 9-ANM-Seattle-ACO-AMOC-Requests@faa.gov.
    (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.

[[Page 42716]]

(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: 425-917-6447; fax: 425-917-6590; email: 
wayne.lockett@faa.gov.
    (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 206-766-5680; 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 425-227-1221.

    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]
BILLING CODE 4910-13-P
```