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2017-10-22 THE BOEING COMPANY:
Amendment 39-18896; Docket No. FAA-2016-9434; Directorate Identifier 2016-NM-136-AD.

(a) EFFECTIVE DATE

    This AD is effective June 27, 2017.

(b) AFFECTED ADS

    None.

(c) APPLICABILITY

(1) This AD applies to The Boeing Company Model 737-600, -700, -700C, -800
    and -900 series airplanes, certificated in any category, as identified
    in Boeing Alert Service Bulletin 737-53A1353, dated July 21, 2016.

(2) Installation of Supplemental Type Certificate (STC) ST00830SE [http://
    rgl.faa.gov/Regulatory_and_Guidance_Library/rgstc.nsf/0/184DE9A71EC3FA
    5586257EAE00707DA6?OpenDocument&Highlight=st00830se]  does not  affect
    the ability to accomplish the actions required by this AD.  Therefore,
    for  airplanes  on  which  STC ST00830SE  is  installed,  a "change in
    product" alternative method of compliance  (AMOC)  approval request is
    not necessary to comply with the requirements of 14 CFR 39.17.

(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 the web lap splices in the aft pressure bulkhead
    are subject to widespread fatigue damage (WFD). We are issuing this AD
    to  detect  and correct  cracks  of the  web  lap splices  in  the aft
    pressure bulkhead, which could result in possible rapid  decompression
    and loss of structural integrity of the airplane.

(f) COMPLIANCE

    Comply with this AD within the compliance times specified,  unless al-
    ready done.

(g) REPETITIVE INSPECTIONS

    Except as provided by paragraph (h) of this AD, at the applicable time
    specified in  paragraph 1.E.,  "Compliance,"  of  Boeing Alert Service
    Bulletin 737-53A1353,  dated July 21, 2016:  Do  a  low frequency eddy
    current (LFEC) inspection to detect cracking of each web lap splice of
    the aft pressure bulkhead at the fastener row common to the stiffener,
    and a high frequency eddy current (HFEC) inspection to detect cracking
    of each web lap  splice of the aft  pressure bulkhead at the  fastener
    row not common to the stiffener, in accordance with the Accomplishment
    Instructions of Boeing Alert Service Bulletin 737-53A1353, dated  July
    21, 2016.

(1) If no crack is found: Repeat the inspections thereafter at the applic-
    able times specified in paragraph 1.E.,  "Compliance," of Boeing Alert
    Service Bulletin 737-53A1353, dated July 21, 2016.

(2) If any crack is found:  Do the actions  specified in paragraphs (g)(2)
    (i) and (g)(2)(ii) of this AD.

(i) Repair  the  crack  before further flight  using  a method approved in
    accordance with the procedures specified in paragraph (i)  of this AD.
    Although  Boeing  Alert Service Bulletin 737-53A1353,  dated  July 21,
    2016,  specifies to contact Boeing for repair instructions, and speci-
    fies that action as "RC" (Required for Compliance),  this AD  requires
    repair as specified in this paragraph.

(ii) On areas that are not repaired,  repeat the inspections thereafter at
     the applicable times specified  in paragraph 1.E.,  "Compliance,"  of
     Boeing Alert Service Bulletin 737-53A1353, dated July 21, 2016.

(h) SERVICE INFORMATION EXCEPTION

    Where paragraph 1.E.,  "Compliance,"  of Boeing Alert Service Bulletin
    737-53A1353, dated July 21, 2016,  specifies a compliance  time "after
    the Original Issue  date of this  Service Bulletin," this  AD requires
    compliance within  the specified  compliance time  after the effective
    date of this AD.

(i) 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  (j) 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 in-
    spector,  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, modification, or alteration  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.  To be  approved,  the repair  method,
    modification  deviation,  or   alteration  deviation  must   meet  the
    certification  basis   of  the   airplane,  and   the  approval   must
    specifically refer to this AD.

(4) Except as required by paragraph (g)(2)(i) of this AD:  For service in-
    formation that contains steps that are labeled as RC,  the  provisions
    of paragraphs (i)(4)(i) and (i)(4)(ii) of this AD apply.

(i) The steps labeled as RC,  including substeps under an RC step  and any
    figures identified in an RC step, must be done to comply with the  AD.
    If a step or substep is  labeled "RC Exempt," then the RC  requirement
    is removed  from that  step or  substep. An  AMOC is  required for any
    deviations to RC steps, including substeps and identified figures.

(ii) Steps  not  labeled as RC may be deviated from using accepted methods
     in accordance with the operator's maintenance  or  inspection program
     without obtaining approval of an AMOC, provided the RC steps, includ-
     ing substeps and identified figures,  can still be done as specified,
     and the airplane can be put back in an airworthy condition.

(j) RELATED INFORMATION

    For  more  information  about this AD,  contact  Alan Pohl,  Aerospace
    Engineer, Airframe Branch, ANM-120S,  FAA, Seattle ACO, 1601 Lind Ave-
    nue SW, Renton, WA 98057-3356; phone: 425-917-6450; fax: 425-917-6590;
    email: alan.pohl@faa.gov.

(k) 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 Alert Service Bulletin 737-53A1353, dated July 21, 2016.

(ii) Reserved.

(3) For  service  information  identified  in  this  AD,   contact  Boeing
    Commercial Airplanes,  Attention:  Contractual & Data Services (C&DS),
    2600 Westminster Blvd., MC 110-SK57, Seal Beach, CA 90740;  telephone:
    562-797-1717; Internet: https://www.myboeingfleet.com.

(4) You may view this 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.

(5) 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 May 10, 2017.  Jeffrey E. Duven, Manager,
Transport Airplane Directorate, Aircraft Certification Service.

FOR FURTHER INFORMATION CONTACT: Alan Pohl,  Aerospace Engineer,  Airframe
Branch, ANM-120S,  FAA,  Seattle Aircraft Certification Office (ACO), 1601
Lind Avenue SW., Renton, WA 98057-3356; phone: 425-917-6450; fax: 425-917-
6590; email: alan.pohl@faa.gov.
PREAMBLE 

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2016-9434; Directorate Identifier 2016-NM-136-AD;
Amendment 39-18896; AD 2017-10-22]
RIN 2120-AA64

Airworthiness Directives; The Boeing Company Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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

SUMMARY: We are adopting a new airworthiness directive (AD) for certain
The Boeing Company Model 737-600, -700, -700C, -800, and -900 series
airplanes. This AD was prompted by an evaluation by the design approval
holder (DAH) indicating that the web lap splices in the aft pressure
bulkhead are subject to widespread fatigue damage (WFD). This AD
requires repetitive inspections of the web lap splices in the aft
pressure bulkhead for cracking of the fastener holes, and repair if
necessary. We are issuing this AD to address the unsafe condition on
these products.

DATES: This AD is effective June 27, 2017.
The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in this AD as of June 27,
2017.

ADDRESSES: For service information identified in this final rule,
contact Boeing Commercial Airplanes, Attention: Contractual & Data
Services (C&DS), 2600 Westminster Blvd., MC 110-SK57, Seal Beach, CA
90740; telephone: 562-797-1717; 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-2016-9434.

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-2016-
9434; 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: Alan Pohl, Aerospace Engineer,
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office
(ACO), 1601 Lind Avenue SW., Renton, WA 98057-3356; phone: 425-917-
6450; fax: 425-917-6590; email: alan.pohl@faa.gov.

SUPPLEMENTARY INFORMATION:

Discussion

We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR
part 39 by adding an AD that would apply to certain The Boeing Company
Model 737-600, -700, -700C, -800, and -900 series airplanes. The NPRM
published in the Federal Register on December 5, 2016 (81 FR 87496)
(``the NPRM''). The NPRM was prompted by an evaluation by the DAH
indicating that the web lap splices in the aft pressure bulkhead are
subject to WFD. The NPRM proposed to require repetitive inspections of
the web lap splices in the aft pressure bulkhead for cracking of the
fastener holes, and repair if necessary. We are issuing this AD to
detect and correct cracks of the web lap splices in the aft pressure
bulkhead, which could result in possible rapid decompression and loss
of structural integrity 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 and
the FAA's response to each comment.

Support for the NPRM

Boeing, United Airlines, and commenter Razia Khan concurred with
the content of the NPRM.

Effect of Winglets on Accomplishment of the Proposed Actions

Aviation Partners Boeing stated that installation of winglets, as
provided in Supplemental Type Certificate (STC) ST00830SE, does not
affect the ability to accomplish the actions proposed in the NPRM.
We agree with the commenter. We have redesignated paragraph (c) of
the proposed AD as paragraph (c)(1) of this AD and added paragraph
(c)(2) to this AD to state that installation of STC ST00830SE does not
affect the ability to accomplish the actions required by this AD.
Therefore, for airplanes on which STC ST00830SE is installed, a
``change in product'' alternative method of compliance (AMOC) approval
request is not necessary to comply with the requirements of 14 CFR
39.17.

Request To Omit Inspections of Existing Repairs

Southwest Airlines (SWA) asked that we include provisions for
airplanes on which repairs have been accomplished previously per the
structural repair manual or per an Organization Designation
Authorization (ODA) signed FAA Form 8100-9 to omit the inspections at
the repair locations. SWA noted that these existing repairs would
inhibit the inspections specified in paragraph (g) of the proposed AD.
SWA added that including follow-on actions as an alternative to the
actions specified in Boeing Alert Service Bulletin 737-53A1353, dated
July 21, 2016, when an existing repair inhibits the inspections
required by paragraph (g) of the proposed AD, would also be acceptable.
We do not agree with the commenter's request. We acknowledge that
SWA is requesting relief from additional approval for actions for
existing repaired locations. However, SWA did not identify any specific
structural repair manual (SRM) repairs or provide a general repair
description of repairs previously approved by the Boeing ODA per an FAA
Form 8100-9. These criteria have been published by Boeing in related
service information for similar issues, but not for this particular
issue. Under the provisions of paragraph (i) of this AD, we will
consider requests for approval of an AMOC if appropriate data are
submitted to substantiate that the method would provide an acceptable
level of safety. We have made no change to this AD in this regard.

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 for correcting the unsafe condition; and
Do not add any additional burden upon the public than was
already proposed in the NPRM.
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

We reviewed Boeing Alert Service Bulletin 737-53A1353, dated July
21, 2016. The service information describes procedures for a low
frequency eddy current inspection to detect cracking of each web lap
splice of the aft pressure bulkhead at the fastener row common to the
stiffener, and a high frequency eddy current inspection to detect
cracking of each web lap splice of the aft pressure bulkhead at the
fastener row not common to the stiffener. 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.

Costs of Compliance

We estimate that this AD affects 693 airplanes of U.S. registry.
We estimate the following costs to comply with this AD:

Estimated Costs

Action
Labor cost
Cost per product
Cost on U.S. operators
Inspections 26 work-hours x $85 per hour = $2,210 per inspection cycle $2,210 per inspection cycle $1,531,530 per inspection cycle

We have received no definitive data that would enable us to provide
cost estimates for the on-condition actions specified in this AD.

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

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

1. The authority citation for part 39 continues to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701.

Sec. 39.13 [Amended]

2. The FAA amends Sec. 39.13 by adding the following new airworthiness
directive (AD):