```

[Federal Register Volume 80, Number 218 (Thursday, November 12, 2015)]
[Rules and Regulations]
[Pages 69839-69846]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2015-26616]

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

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2014-0454; Directorate Identifier 2013-NM-138-AD; 
Amendment 39-18298; AD 2015-21-06]
RIN 2120-AA64

Airworthiness Directives; The Boeing Company Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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

SUMMARY: We are superseding Airworthiness Directive (AD) 2002-07-08 for 
certain The Boeing Company

[[Page 69840]]

Model 737 airplanes. AD 2002-07-08 required 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 terminated the 
repetitive inspections of the modified areas; and replacement of a 
certain preventive modification with an improved modification. This new 
AD adds repetitive inspections for cracking at certain window corner 
fastener holes, a preventive modification, and repair if necessary. 
This AD was prompted by the FAA's determination that certain 
modifications of the fuselage lap joints do not provide an adequate 
level of safety, and the subsequent discovery of cracks in additional 
fastener locations in the window belt skin panels, adjacent stringers, 
and window frames in locations outside the previous inspection area. We 
are issuing this AD to detect and correct fatigue cracking of the 
fuselage lap joints and window belt skin panels, which could result in 
reduced structural integrity and sudden decompression of the airplane.

DATES: This AD is effective December 17, 2015.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in this AD as of December 17, 
2015.
    The Director of the Federal Register approved the incorporation by 
reference of certain other publications listed in this AD as of May 17, 
2002 (67 FR 17917, April 12, 2002).

ADDRESSES: 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. It is also available on the Internet at http://www.regulations.gov by searching for and locating Docket No. FAA-2014-
0454.

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 AD, the regulatory evaluation, any comments received, and 
other information. The address for the Docket Office (phone: 800-647-
5527) is Docket Management Facility, U.S. Department of Transportation, 
Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 
New Jersey Avenue SE., Washington, DC 20590.

FOR FURTHER INFORMATION CONTACT: Jennifer Tsakoumakis, Aerospace 
Engineer, Airframe Branch, ANM-120L, FAA, Los Angeles Aircraft 
Certification Office (ACO), 3960 Paramount Boulevard, Lakewood, CA 
90712-4137; phone: 562-627-5264; fax: 562-627-5210; email: 
Jennifer.Tsakoumakis@faa.gov.

SUPPLEMENTARY INFORMATION:

Discussion

    We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR 
part 39 to supersede AD 2002-07-08, Amendment 39-12702 (67 FR 17917, 
April 12, 2002). AD 2002-07-08 applied to certain The Boeing Company 
Model 737 airplanes. The NPRM published in the Federal Register on July 
23, 2014 (79 FR 42710). The NPRM was prompted by the FAA's 
determination that certain modifications of the fuselage lap joints do 
not provide an adequate level of safety, and the subsequent discovery 
of cracks in additional fastener locations in the window belt skin 
panels, adjacent stringers and window frames in locations outside the 
previous inspection area. The NPRM proposed to continue to require 
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 would terminate the repetitive inspections of the modified areas; 
and replacement of a certain preventive modification with an improved 
modification. The NPRM also proposed to require repetitive inspections 
for cracking at certain window corner fastener holes, a preventive 
modification, and repair if necessary. We are issuing this AD to detect 
and correct fatigue cracking of the fuselage lap joints and window belt 
skin panels, which could result in reduced structural integrity and 
sudden decompression of the airplane.

Comments

    We gave the public the opportunity to participate in developing 
this AD. The following presents the comments received on the NPRM (79 
FR 42710, July 23, 2014) and the FAA's response to each comment.

Request To Identify New Inspection Locations

    Boeing requested that we revise the preamble of the NPRM (79 FR 
42710, July 23, 2014), by adding references to new inspection locations 
on the window belt skin panels. Boeing pointed out that the NPRM 
preamble defined structure that has been found to crack since release 
of AD 2002-07-08, Amendment 39-12702 (67 FR 17917, April 12, 2002). 
Boeing also indicated that Boeing Service Bulletin 737-53A1177, 
Revision 7, dated June 14, 2013, provides inspections for skin cracking 
at nine additional fastener holes in the corners of certain passenger 
windows from what is mandated by AD 2002-07-08.
    We agree that clarification is necessary. We have added the 
description of the new inspection locations in the SUMMARY of this 
final rule accordingly. The unspecified inspection areas were accounted 
for in paragraph (p) of the proposed AD (79 FR 42710, July 23, 2014), 
which is retained in this AD.

Request To Remove Post Repair/Modification Requirements

    Boeing requested that we revise the NPRM (79 FR 42710, July 23, 
2014) to remove the ``post-repair/alteration and butt joint repetitive 
inspections'' requirement as specified in paragraph (r) of the proposed 
AD. Boeing pointed out that one of the proposed actions, ``post-repair/
alteration and butt joint repetitive inspections,'' defined in 
paragraph (r) of the proposed AD, refers to damage-tolerance-based 
structural post-repair/post-alteration inspections. Boeing also stated 
that the inspections are provided in the service bulletin for 
operators' use to comply with the operational requirements of 14 CFR 
part 121.1109 and Part 129.109 and, therefore, the inspections do not 
need to be mandated separately in the NPRM.
    We agree with the request. As Boeing stated, the inspections that 
were specified in paragraph (r) of the proposed AD (79 FR 42710, July 
23, 2014) may be used in support of compliance with section 
121.1109(c)(2) or 129.109(b)(2) of the Federal Aviation Regulations (14 
CFR 121.1109(c)(2) or 129.109(b)(2)). However, this AD does not require 
those post-modification inspections. We have therefore removed 
paragraph (r) of the proposed AD and redesignated subsequent paragraphs 
accordingly. We have also revised the SUMMARY of this final rule to 
remove reference to the inspections.

[[Page 69841]]

Request To Reference Related AD

    Boeing requested that we clarify the ``Difference Between the 
Proposed AD and the Service Information'' section of the NPRM (79 FR 
42710, July 23, 2014), by adding a reference to AD 2002-07-11, 
Amendment 39-12705 (67 FR 17931, April 12, 2002), for Model 737 
airplanes, line numbers 1 through 291 inclusive. Boeing pointed out 
that the ``Difference Between the Proposed AD and the Service 
Information'' section of the NPRM (79 FR 42710, July 23, 2014) defined 
the applicability of the NPRM as Model 737 airplanes, line numbers 292 
through 2565 inclusive, and explained that Model 737 airplanes, line 
numbers 1 through 291 inclusive, have been addressed by AD 2003-23-03, 
Amendment 39-13367 (68 FR 64980, November 18, 2003). Boeing also 
indicated that AD 2002-07-11, Amendment 39-12705 (67 FR 17931, April 
12, 2002), addresses Model 737 airplanes line numbers 1 through 291 
inclusive, and mandates the actions defined in Boeing Service Bulletin 
737-53A1177, Revision 6, dated May 31, 2001.
    Although the ``Difference Between the Proposed AD and the Service 
Information'' section of the NPRM (79 FR 42710, July 23, 2014) is not 
restated in this final rule, we agree with the commenter's 
clarification of the applicability. Paragraph (c) of this AD is 
retained as proposed in the NPRM, and no change has been made to this 
AD regarding this issue.

Request for Additional Exception

    Boeing requested that we clarify paragraph (g) of the proposed AD 
(79 FR 42710, July 23, 2014), to include an additional exception. 
Boeing pointed out that paragraph (g) of the proposed AD provided an 
exception for paragraph (h) of the proposed AD to address lap joint 
modification (repair) instructions for certain lap joint areas on 737-
200 and 737-200C airplanes. Boeing also indicated that paragraph (q)(2) 
of the proposed AD addresses an optional terminating action, window 
belt replacement for 737-300 and 737-500 airplanes, for the lap joint 
modification. Boeing also stated that paragraph (q)(2) of the proposed 
AD should be included as an exception for the lap joint modification 
(repair) defined in paragraph (g) of the proposed AD.
    We agree with the request for an additional exception. We revised 
paragraph (g) of this AD to include a reference to paragraph (q)(2) of 
this AD as an exception.

Request for New Exception

    Boeing requested that we clarify paragraph (m) of the proposed AD 
(79 FR 42710, July 23, 2014), to include an exception. Boeing indicated 
that Boeing Service Bulletin 737-53A1177, Revision 7, dated June 14, 
2013, added an optional window belt skin panel replacement as 
terminating action for the S-10 and S-14 lap joint inspections and for 
the window corner inspections on Model 737-300 and 737-500 airplanes. 
Boeing also stated that paragraph (q) of the proposed AD addressed the 
optional terminating action, and that follow-on inspections are also 
necessary for the optional window belt skin panel replacement, and 
paragraph (q) of the proposed AD should be added as an exception to 
paragraph (m) of the proposed AD.
    We disagree with the request to include an exception. Paragraph (q) 
of this AD is an optional action and terminates only paragraph (g) of 
this AD. If an operator chooses to use the modification option in 
paragraph (q) of this AD to do the repair required by paragraph (g) of 
this AD, the requirements of paragraph (m) of this AD have not been 
terminated, and those inspections must be accomplished. We have not 
changed this AD regarding this issue.

Request for Additional Instruction

    Boeing requested that we clarify paragraph (m) of the proposed AD 
(79 FR 42710, July 23, 2014), to include instruction for any crack 
found by the inspections. Boeing stated that paragraph (m) of the 
proposed AD contains follow-on inspections of the lap joint 
modification, which are contained in the Compliance and Accomplishment 
Instructions of Boeing Service Bulletin 737-53A1177, Revision 7, dated 
June 14, 2013. Boeing also stated that if any crack is found during the 
follow-on inspections, the Compliance section of Boeing Service 
Bulletin 737-53A1177, Revision 7, dated June 14, 2013, instructs 
operators to contact Boeing for repair instructions; therefore, 
reference to paragraph (s)(2) of the proposed AD should be added to 
paragraph (m) of the proposed AD.
    We agree with the request to include instruction for any crack 
found by the inspections. The instructions for repair were 
inadvertently omitted in paragraph (m) of AD 2002-07-08, Amendment 39-
12702 (67 FR 17917, April 12, 2002). The associated service information 
recommended that this repair be done by contacting Boeing for 
instructions. However paragraph (s)(2) of the proposed AD (79 FR 42710, 
July 23, 2014) specifically directed operators to contact the FAA for 
instructions when the service information specified to contact Boeing. 
We revised paragraph (m) of this AD to refer to paragraph (t) of this 
AD, which provides directions to request approval of an alternative 
method of compliance (AMOC).

Request To Remove Reference to Paragraphs (m) and (n) of the Proposed 
AD (79 FR 42710, July 23, 2014)

    Boeing requested that we clarify paragraph (o) of the proposed AD 
(79 FR 42710, July 23, 2014), by removing references to paragraphs (m) 
and (n) of the proposed AD. Boeing indicated that paragraph (o) of the 
proposed AD addresses repair of crack damage and references PART II of 
the Accomplishment Instructions of Boeing Service Bulletin SB 737-
53A1177, Revision 7, dated June 14, 2013. Boeing also stated that PART 
II of Boeing Service Bulletin SB 737-53A1177, Revision 7, dated June 
14, 2013, provides instructions for repair of cracks found in the lower 
skin of the lower row of the production lap joint, which could be found 
by the inspections defined in paragraphs (i), (j), and (k) of the 
proposed AD. Boeing pointed out that cracks found by the inspections in 
paragraphs (m) and (n) of the proposed AD are addressed individually by 
the same paragraphs respectively (with changes to paragraph (m) of the 
proposed AD, as discussed in the previous comment); therefore, repair 
of any crack found during the inspections in paragraphs (m) and (n) of 
the proposed AD should not be included in paragraph (o) of the proposed 
AD.
    We agree with the request to revise paragraph (o) of this AD (79 FR 
42710, July 23, 2014) to remove references to paragraphs (m) and (n) of 
the AD, for the reasons provided by the commenter. We revised paragraph 
(o) of this AD accordingly.

Request To Revise Paragraph (q)(1) of the Proposed AD (79 FR 42710, 
July 23, 2014)

    Boeing requested that we clarify paragraph (q)(1) of the proposed 
AD (79 FR 42710, July 23, 2014), by revising the wording for 
consistency with paragraph (q)(2) of the proposed AD, adding references 
to inspections in paragraph (n) of the proposed AD that are terminated 
by the actions in paragraph (q)(2) of the proposed AD, and adding 
wording to limit the number of window inspections that can be 
terminated by the replacement panel. Boeing pointed out that paragraphs 
(q)(1) and (q)(2) of the proposed AD address the same action, 
replacement of window belt skin

[[Page 69842]]

panels. Boeing also pointed out that the inspections in paragraph (n) 
of the proposed AD, Retained Repetitive HFEC Inspections of the Window 
Corners, can also be terminated by replacement of the window belt panel 
and therefore, wording should be added to paragraph (q)(1) of the 
proposed AD to ensure inspections would only be terminated at window 
corners common to the replaced panel.
    We partially agree. We agree to reword paragraph (q)(1) of this AD 
because consistent language makes the AD easier to read, and 
replacement of a panel will terminate the inspections only for the 
panel that is replaced. We disagree to add references to inspections in 
paragraph (n) of this AD, as Boeing proposed. Paragraph (q)(1) of this 
AD terminates the actions required by paragraph (p) of this AD, and 
doing the actions required by paragraph (p) of this AD terminates the 
inspections required by paragraph (n) of this AD.

Request To Revise Paragraph (q)(2) of the Proposed AD (79 FR 42710, 
July 23, 2014)

    Boeing requested that we clarify paragraph (q)(2) of the proposed 
AD (79 FR 42710, July 23, 2014), by revising the wording to show that 
the optional window belt skin panel replacement terminates the lap 
joint lower row inspections of AD 2013-09-01, Amendment 39-17442 (78 FR 
27001, May 9, 2013), rather than terminating the lap joint 
modification. Boeing pointed out that paragraph (q)(2) of the proposed 
AD addresses an optional window belt skin panel replacement. Boeing 
also indicated that the skin panel replacement was included in Boeing 
Service Bulletin SB 737-53A1177, Revision 7, dated June 14, 2013, to 
provide an option for operators to terminate the lap joint lower row 
inspections, and was mandated by paragraphs (g) and (i) of AD 2013-09-
01, in lieu of the lap joint modification which is addressed by 
paragraph (g) of the proposed AD.
    We agree with the request for the reasons provided by the 
commenter. There is a direct AMOC connection between the window belt 
skin panel replacement and the inspections required by paragraphs (g) 
and (i) of this AD. However, we have added new paragraph (q)(3) of this 
AD to explain that the skin panel replacement terminates the specified 
inspections required by paragraphs (g) and (i) of AD 2013-09-01, 
Amendment 39-17442 (78 FR 27001, May 9, 2013), for the replaced skin 
panel only.

Request To Change FAA Contact Information

    Boeing requested that we clarify paragraphs (t)(1) and (t)(2) of 
the proposed AD (79 FR 42710, July 23, 2014), by revising the wording 
to reference the Manager of the Los Angeles ACO instead of the Manager 
of the Seattle ACO. Boeing indicated that responsibility for the 737 
Classic models (which include the airplanes affected by this AD) has 
been transferred from the Seattle ACO to the Los Angeles ACO and that 
authority for approval of AMOCs for the proposed AD should be changed 
from the Manager, Seattle ACO, to the Manager, Los Angeles ACO.
    We infer that Boeing requested that we clarify paragraphs (t)(1) 
and (t)(3) of the proposed AD (79 FR 42710, July 23, 2014).
    We agree with the request, and have revised paragraphs (t)(1) and 
(t)(3) of this AD as requested, and included the following in paragraph 
(t)(1) of this AD: 9-ANM-LAACO-AMOC-Requests@faa.gov. We also revised 
paragraph (u) of this AD to include the appropriate contact 
information.

Additional Changes to This Final Rule

    We have included a new paragraph (s) in this AD to provide credit 
for accomplishing lap joint repair before the effective date of this AD 
using 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. The subsequent paragraphs have been redesignated 
accordingly.

Conclusion

    We reviewed the relevant data, considered the comments received, 
and determined that air safety and the public interest require adopting 
this AD with the changes described previously and minor editorial 
changes. We have determined that these minor changes:
     Are consistent with the intent that was proposed in the 
NPRM (79 FR 42710, July 23, 2014) for correcting the unsafe condition; 
and
     Do not add any additional burden upon the public than was 
already proposed in the NPRM (79 FR 42710, July 23, 2014).
    We also determined that these changes will not increase the 
economic burden on any operator or increase the scope of this AD.

Related Service Information Under 1 CFR Part 51

    Boeing has issued Service Bulletin 737-53A1177, Revision 7, dated 
June 14, 2013. The service information procedures for 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 to 
terminate the repetitive inspections of the modified areas; replacement 
of a certain preventive modification with an improved modification; 
repetitive inspections for cracking at certain window corner fastener 
holes; a preventive modification; and repair. This service information 
is reasonably available because the interested parties have access to 
it through their normal course of business or by the means identified 
in the ADDRESSES section of this AD.

Costs of Compliance

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

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                                                 Cost on U.S.
             Action                   Labor cost          Parts cost       Cost per  product       operators
----------------------------------------------------------------------------------------------------------------
Retained lap joint modification.  4,650 work-hours x  Up to $204,000....  $599,250..........  $95,280,750
                                   $85 per hour =                                              (estimated 159
                                   $395,250.                                                   airplanes).
Retained lap joint inspection...  90 work-hours x     $0................  $7,650 per          $1,889,550 per
                                   $85 per hour =                          inspection cycle.   inspection cycle.
                                   $7,650 per
                                   inspection cycle.
Retained post-NACA inspection...  110 work-hours x    $0................  $9,350 per          $308,550 per
                                   $85 per hour =                          inspection cycle.   inspection cycle
                                   $9,350 per                                                  (estimated 33
                                   inspection cycle.                                           airplanes).

[[Page 69843]]

 
Retained window corner            36 work-hours x     $0................  $3,060 per          $755,820 per
 inspection.                       $85 per hour =                          inspection cycle.   inspection cycle.
                                   $3,060 per
                                   inspection cycle.
New window corner inspection....  108 work-hours x    $0................  $9,180 per          $2,267,460 per
                                   $85 per hour =                          inspection cycle.   inspection cycle.
                                   $9,180 per
                                   inspection cycle.
----------------------------------------------------------------------------------------------------------------

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

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

                                               On-Condition Costs
----------------------------------------------------------------------------------------------------------------
                                                                                                     Cost per
                    Action                                Labor cost               Parts cost        product
----------------------------------------------------------------------------------------------------------------
Window corner repair, per corner.............  9 work-hours x $85 per hour =             (\1\)             $765
                                                $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 AD, and that no operator will accomplish those actions in the 
future if this AD is 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 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 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),
    (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.

Adoption of the Amendment

    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 removing Airworthiness Directive (AD) 
2002-07-08, Amendment 39-12702 (67 FR 17917, April 12, 2002), and 
adding the following new AD:

2015-21-06 The Boeing Company: Amendment 39-18298; Docket No. FAA-
2014-0454; Directorate Identifier 2013-NM-138-AD.

(a) Effective Date

    This AD is effective December 17, 2015.

(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.

[[Page 69844]]

(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 paragraphs 
(h) and (q)(2) 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 or internal 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. The external and internal LFEC inspections are specified in 
Figures 8 and 9, respectively, of Boeing Service Bulletin 737-
53A1177, Revision 6, dated May 31, 2001; and 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

[[Page 69845]]

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 or internal 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. The external and internal 
LFEC inspections are specified in Figures 8 and 9, respectively, of 
Boeing Service Bulletin 737-53A1177, Revision 6, dated May 31, 2001; 
and 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 
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. Repair any crack found before further flight using a method 
approved in accordance with the procedures specified in paragraph 
(t) of this AD. The internal LFEC inspection is specified in Figure 
9 of Boeing Service Bulletin 737-53A1177, Revision 6, dated May 31, 
2001; and 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), or (k) 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 (r)(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, ``Compliance,'' of Boeing Service Bulletin 737-
53A1177, Revision 7, dated June 14, 2013, except as required by 
paragraph (r)(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 (r)(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 (r)(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, ``Compliance,'' 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) Replacement of the skin panel as 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 for the windows common to the 
replaced panel only.
    (2) Replacement of the skin panel as 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 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.
    (3) Replacement of the skin panels as 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 inspections required by paragraphs (g)

[[Page 69846]]

and (i) of AD 2013-09-01, Amendment 39-17442 (78 FR 27001, May 9, 
2013), for the replaced skin panel only.

(r) 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.

(s) Credit for Previous Actions

    (1) This paragraph provides credit for the actions required by 
paragraph (g) of this AD, if those actions were performed before the 
effective date of this AD using the applicable service information 
specified in paragraphs (s)(1)(i), (s)(1)(ii), and (s)(1)(iii) of 
this AD, which were incorporated by reference in AD 2002-07-08, 
Amendment 39-12702 (67 FR 17917, April 12, 2002).
    (i) Boeing Service Bulletin 737-53A1177, Revision 4, dated 
September 2, 1999.
    (ii) Boeing Service Bulletin 737-53A1177, Revision 5, dated 
February 15, 2001, which continues to be incorporated by reference 
in this AD.
    (iii) Boeing Service Bulletin 737-53A1177, Revision 6, dated May 
31, 2001, which continues to be incorporated by reference in this 
AD.
    (2) This paragraph provides credit for the actions required by 
paragraphs (i) through (o) of this AD, if those actions were 
performed before the effective date of this AD using Boeing Service 
Bulletin 737-53A1177, Revision 6, dated May 31, 2001, which was 
incorporated by reference in AD 2002-07-08, Amendment 39-12702 (67 
FR 17917, April 12, 2002) and continues to be incorporated by 
reference in this AD.

(t) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, Los Angeles 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-LAACO-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, Los Angeles 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 Jennifer 
Tsakoumakis, Aerospace Engineer, Airframe Branch, ANM-120L, FAA, Los 
Angeles Aircraft Certification Office (ACO), 3960 Paramount 
Boulevard, Lakewood, CA 90712-4137; phone: 562-627-5264; fax: 562-
627-5210; email: Jennifer.Tsakoumakis@faa.gov.
    (2) Service information identified in this AD that is not 
incorporated by reference is available at the addresses specified in 
paragraphs (v)(3) and (v)(4) of this AD.

(v) Material Incorporated by Reference

    (1) The Director of the Federal Register approved the 
incorporation by reference (IBR) of the service information listed 
in this paragraph under 5 U.S.C. 552(a) and 1 CFR part 51.
    (2) You must use this service information as applicable to do 
the actions required by this AD, unless the AD specifies otherwise.
    (i) Boeing Service Bulletin 737-53A1177, Revision 7, dated June 
14, 2013.
    (ii) Reserved.
    (3) The following service information was approved for IBR on 
May 17, 2002 (67 FR 17917, April 12, 2002).
    (i) Boeing Service Bulletin 737-53A1177, Revision 5, dated 
February 15, 2001.
    (ii) Boeing Service Bulletin 737-53A1177, Revision 6, dated May 
31, 2001.
    (4) For Boeing 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.
    (5) You may view this service information at 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.
    (6) You may view this service information that is incorporated 
by reference at the National Archives and Records Administration 
(NARA). For information on the availability of this material at 
NARA, call 202-741-6030, or go to: http://www.archives.gov/federal-register/cfr/ibr-locations.html.

    Issued in Renton, Washington, on October 11, 2015.
Jeffrey E. Duven,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2015-26616 Filed 11-10-15; 8:45 am]
 BILLING CODE 4910-13-P
```