82 FR 24468 - Airworthiness Directives; The Boeing Company Airplanes

DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration

Federal Register Volume 82, Issue 102 (May 30, 2017)

We are superseding Airworthiness Directive (AD) 2009-21-01 for certain The Boeing Company Model 737-300 and 737-400 series airplanes. AD 2009-21-01 required repetitive inspections to detect cracking of the aft fuselage skin, and related investigative and corrective actions if necessary. This new AD adds certain inspections, repairs, replacement, related investigative and corrective actions if necessary; and removes certain airplanes from the applicability. This AD was prompted by an evaluation by the design approval holder (DAH) indicating that the aft fuselage skin is subject to widespread fatigue damage (WFD), and by reports of aft fuselage cracking. We are issuing this AD to address the unsafe condition on these products.

[Federal Register Volume 82, Number 102 (Tuesday, May 30, 2017)]
[Rules and Regulations]
[Pages 24468-24472]
From the Federal Register Online  [www.thefederalregister.org]
[FR Doc No: 2017-10288]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2016-6667; Directorate Identifier 2015-NM-125-AD; 
Amendment 39-18882; AD 2017-10-08]
RIN 2120-AA64


Airworthiness Directives; The Boeing Company Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: We are superseding Airworthiness Directive (AD) 2009-21-01 for 
certain The Boeing Company Model 737-300 and 737-400 series airplanes. 
AD 2009-21-01 required repetitive inspections to detect cracking of the 
aft fuselage skin, and related investigative and corrective actions if 
necessary. This new AD adds certain inspections, repairs, replacement, 
related investigative and corrective actions if necessary; and removes 
certain airplanes from the applicability. This AD was prompted by an 
evaluation by the design approval holder (DAH) indicating that the aft 
fuselage skin is subject to widespread fatigue damage (WFD), and by 
reports of aft fuselage cracking. We are issuing this AD to address the 
unsafe condition on these products.

DATES: This AD is effective July 5, 2017.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in this AD as of July 5, 
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 
90740-5600; 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-
6667.

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-
6667; 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: 
[email protected].

SUPPLEMENTARY INFORMATION: 

Discussion

    We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR 
part 39 to supersede AD 2009-21-01, Amendment 39-16038 (74 FR 52395, 
October 13, 2009) (``AD 2009-21-01''). AD 2009-21-01 applied to certain 
the Boeing Company Model 737-300 and 737-400 series airplanes. The NPRM 
published in the Federal Register on May 13, 2016 (81 FR 29802). The 
NPRM was prompted by an evaluation by the DAH indicating that the aft 
fuselage skin is subject to WFD, and by reports of aft fuselage 
cracking. The NPRM proposed to continue to require repetitive 
inspections to detect cracking of the aft fuselage skin, and related 
investigative and corrective actions if necessary. The NPRM also 
proposed to add new aft fuselage skin inspections for cracking, 
inspections to detect missing or loose fasteners and any disbonding or 
cracking of bonded doublers, permanent repairs of time-limited repairs, 
related investigative and corrective actions if necessary, and skin 
panel replacement. The NPRM also proposed to remove Model 737-400 
series airplanes from the applicability. We are issuing this AD to 
detect and correct cracking in the aft fuselage skin along the 
longitudinal edges of the chem-milled pockets in the bonded skin 
doubler, which could result in possible rapid decompression and reduced 
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.

Request To Revise the Precipitating Event Statement

    Boeing requested that we revise the precipitating event statement 
by including that there have been reports of aft fuselage cracking. 
Boeing stated that this revision would be consistent with wording of 
other related rulemaking.
    We agree with Boeing's request because it provides additional 
clarity to the precipitating event statement. We have revised the 
SUMMARY and Discussion sections, and paragraph (e) of this AD 
accordingly.

[[Page 24469]]

Request To Require Reinstalling Lap Joint Modification

    Jet2.com Limited (Jet2) requested that we revise the NPRM to 
require reinstalling the lap joint modification previously installed in 
accordance with AD 2015-21-06, Amendment 39-18298 (80 FR 69839, 
November 12, 2015) (``AD 2015-21-06''), which requires the S-14 lap 
joint to be trimmed out prior to 50,000 total flight cycles. Jet2 
stated that Boeing Special Attention Service Bulletin 737-53-1168, 
Revision 4, dated June 3, 2015 (``SASB 737-53-1168, Revision 4'') 
specifies reinstalling the lap joint modification.
    We do not agree with the commenter's request. The modification 
required in AD 2015-21-06 consists of trimming out the lap splice, such 
that if this modification were installed, it would be impossible to 
install a new skin without reinstalling the lap modification. If the 
instructions in SASB 737-53-1168, Revision 4, to reinstall the lap 
splice modification were accidently overlooked, it would become clear 
to the installer that the reinstallation would be required. We have not 
changed this AD in this regard.

Request To Address Certain Repairs

    Boeing requested that we add a paragraph to the proposed AD to 
address repairs that are installed on the airplane for reasons other 
than chem-mill cracking. Boeing submitted suggested language and 
pointed out that the additional language is similar to that in other 
rulemaking.
    We disagree with Boeing's request. Part 1 of the Accomplishment 
Instructions of SASB 737-53-1168, Revision 4, does not make a 
distinction regarding why an existing repair was installed. Therefore, 
repairs installed for damage other than a chem-mill crack are already 
addressed. We have not changed this AD in this regard.

Request To Revise Proposed Compliance Time

    Boeing requested that we revise paragraph (h)(4) of the proposed AD 
to do the actions at an initial compliance time obtained through the 
alternative method of compliance (AMOC) process specified in paragraph 
(n)(1) of the proposed AD. Boeing stated that the repetitive 
inspections would still be done at the times specified in the service 
information. Boeing also requested that we include in the paragraph 
revision the terminating action of skin panel replacement at the time 
approved through an AMOC. Boeing stated that its request would provide 
a reset on the compliance times if the skin panel was replaced prior to 
53,000 total airplane cycles. Boeing explained that its authorized 
representative under the Boeing Commercial Airplanes Organization 
Designation Authorization (ODA) cannot approve extensions to the 
compliance times.
    We partially agree with Boeing's request. We agree that, for 
airplanes with skin panels replaced prior to 53,000 total flight 
cycles, in order to reset the inspection threshold on the replaced skin 
panels, approval must come from the FAA. Under the provisions of 
paragraph (n) of this AD, we may consider requests for a reset of the 
compliance times if the skin panel was replaced prior to 53,000 total 
airplane cycles if data are submitted to substantiate that such an 
adjustment would provide an acceptable level of safety. We have not 
changed this AD in this regard.

Request To Specify the Service Information Accomplishment Instructions 
Part Numbers

    Boeing requested that we add the specific part of the 
accomplishment instructions in paragraphs (i)(1)(ii), (i)(2)(ii), and 
(j) of the proposed AD. Boeing stated that paragraph (g) of the 
proposed AD specifies the specific part number, and that this change 
would make these paragraphs consistent with the wording in paragraph 
(g) of the proposed AD.
    We agree with Boeing's request. We agree that specifying the 
specific part of the Accomplishment Instructions of SASB 737-53-1168, 
Revision 4, will add clarity to the AD. We have revised paragraphs 
(i)(1)(ii), (i)(2)(ii), and (j) of this AD accordingly.

Request To Revise Flight Cycle Limit for Replacement Kit Skin Panels

    Boeing requested that we revise paragraph (l) of the proposed AD to 
specify that skin panel replacements using the kit identified in SASB 
737-53-1168, Revision 4, do not have the lower flight cycle limit 
restriction that the production skin panel replacements have.
    We agree with Boeing's request because the skin panel replacements 
using the kit identified in SASB 737-53-1168, Revision 4, is an 
improved design compared to the production skin panels, and therefore, 
do not need the lower flight cycle limit restriction. We have added 
paragraph (l)(3) to this AD, which states, in part, that if the skin 
panel is replaced with a kit skin panel as specified in SASB 737-53-
1168, Revision 4, the 53,000 total flight cycle limit does not apply.

Request To Remove Flight-Cycle Restriction for Certain Actions

    Boeing requested that we revise paragraphs (m)(2), (m)(3), and 
(n)(5) of the proposed AD to remove the flight cycle restriction for 
certain previously accomplished actions using certain service 
information. Boeing stated that the only skin panel replacements 
specified in previous revisions of SASB 737-53-1168 are those using the 
kit panels, and that those panels do not have the flight-cycle limit 
specified in paragraphs (m)(2), (m)(3), and (n)(5) of the proposed AD.
    We agree with the commenter's request because the skin panel 
replacements using the kit identified in SASB 737-53-1168, Revision 4, 
are an improved design compared to the production skin panels, and 
therefore, do not need the lower flight cycle limit restriction. We 
have revised paragraphs (m)(2), (m)(3), and (n)(5) of this AD 
accordingly.

Request To Specify Terminating Action

    Qantas Airways Limited (Qantas) requested that we revise paragraphs 
(g) and (l) of the proposed AD to specify terminating action. Qantas 
pointed out that replacing the skin panels with kit panels instead of 
production panels, as specified in SASB 737-53-1168, terminates the 
repetitive inspections identified in paragraphs (g), (i), and (j) of 
the proposed AD. Additionally, Qantas pointed out that replacement with 
kit skin panels using any revision of SASB 737-53-1168 before the 
effective date of the AD should also terminate the repetitive 
inspections identified in paragraphs (g), (i), and (j) of the proposed 
AD.
    We agree with the commenter's request because the skin panel 
replacements using the kit identified in SASB 737-53-1168, Revision 4, 
are an improved design compared to the production skin panels and 
therefore, should terminate the repetitive inspections. We have revised 
paragraphs (m)(2), (m)(3), and (n)(5) of this AD accordingly.

Effect of Winglets on Accomplishment of the Proposed Actions

    Aviation Partners Boeing stated that accomplishing Supplemental 
Type Certificate (STC) ST01219SE does not affect the actions specified 
in the NPRM.
    We concur 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 ST01219SE does not 
affect the ability to

[[Page 24470]]

accomplish the actions required by this final rule. Therefore, for 
airplanes on which STC ST01219SE is installed, a ``change in product'' 
AMOC approval request is not necessary to comply with the requirements 
of 14 CFR 39.17.

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 SASB 737-53-1168, Revision 4. The service information 
describes procedures for doing inspections of the fuselage skin, 
repairs, and skin panel replacement. 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 168 airplanes of U.S. registry.
    We estimate the following costs to comply with this AD:

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                         Cost per
            Action                  Labor cost         Parts cost        product        Cost on U.S.  operators
----------------------------------------------------------------------------------------------------------------
Inspections..................  Up to 1,791 work-                 $0  Up to $152,235.  Up to $25,575,480.
                                hours x $85 per
                                hour = $152,235.
Skin replacement.............  624 work-hours x $85          98,275  $151,315.......  $25,420,920.
                                per hour = $53,040.
----------------------------------------------------------------------------------------------------------------

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

                                               On-Condition Costs
----------------------------------------------------------------------------------------------------------------
             Action                      Labor cost           Parts cost              Cost per product
----------------------------------------------------------------------------------------------------------------
Time-limited repair.............  24 work-hours x $85 per            (\1\)  $2,040 per repair.
                                   hour = $2,040 per
                                   repair.
Permanent repair................  Up to 43 work[dash]hours           (\1\)  Up to $3,655 per repair.
                                   x $85 per hour = $3,655
                                   per repair.
----------------------------------------------------------------------------------------------------------------
\1\ We have received no definitive data that would enable us to provide the part cost estimates for the on-
  condition actions specified in this AD.

    We estimate the following costs to do any necessary post-repair 
inspections that would be required. We have no way of determining the 
number of aircraft that might need these inspections:

                                          Post-Repair Inspection Costs
----------------------------------------------------------------------------------------------------------------
             Action                      Labor cost           Parts cost              Cost per product
----------------------------------------------------------------------------------------------------------------
Post-repair inspection..........  Up to 7 work[dash]hours               $0  Up to $595.
                                   x $85 per hour = $595.
----------------------------------------------------------------------------------------------------------------

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,

[[Page 24471]]

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) 
2009-21-01, Amendment 39-16038 (74 FR 52395, October 13, 2009), and 
adding the following new AD:

2017-10-08 The Boeing Company: Amendment 39-18882; Docket No. FAA-
2016-6667; Directorate Identifier 2015-NM-125-AD.

(a) Effective Date

    This AD is effective July 5, 2017.

(b) Affected ADs

    This AD replaces AD 2009-21-01, Amendment 39-16038 (74 FR 52395, 
October 13, 2009) (``AD 2009-21-01'').

(c) Applicability

    (1) This AD applies to The Boeing Company Model 737-300 series 
airplanes, certificated in any category, as identified in Boeing 
Special Attention Service Bulletin 737-53-1168, Revision 4, dated 
June 3, 2015 (``SASB 737-53-1168, Revision 4'').
    (2) Installation of Supplemental Type Certificate (STC) 
ST01219SE (http://rgl.faa.gov/Regulatory_and_Guidance_Library/
rgstc.nsf/0/ebd1cec7b301293e86257cb30045557a/$FILE/ST01219SE.pdf) 
does not affect the ability to accomplish the actions required by 
this AD. Therefore, for airplanes on which STC ST01219SE 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 aft fuselage skin is subject to 
widespread fatigue damage (WFD), and reports of aft fuselage 
cracking. We are issuing this AD to detect and correct cracking in 
the aft fuselage skin along the longitudinal edges of the chem-
milled pockets in the bonded skin doubler, which could result in 
possible rapid decompression and reduced structural integrity of the 
airplane.

(f) Compliance

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

(g) Inspections, Related Investigative and Corrective Actions

    At the applicable times specified in tables 1 and 2 of paragraph 
1.E., ``Compliance,'' of SASB 737-53-1168, Revision 4, except as 
required by paragraphs (h)(1) and (h)(2) of this AD: Do the 
applicable inspections to detect cracks in the aft fuselage skin 
panels, and do all applicable related investigative and corrective 
actions, in accordance with the Accomplishment Instructions of SASB 
737-53-1168, Revision 4, except as required by paragraphs (h)(3) and 
(h)(4) of this AD. Do all applicable related investigative and 
corrective actions before further flight. Repeat the applicable 
inspections thereafter at the applicable intervals specified in 
tables 1 and 2 of paragraph 1.E., ``Compliance,'' of SASB 737-53-
1168, Revision 4. Accomplishment of a repair in accordance with 
``Part 4: Repair'' of the Accomplishment Instructions of SASB 737-
53-1168, Revision 4, except as required by paragraph (h)(3) of this 
AD, is terminating action for the repetitive inspections required by 
this paragraph at the repaired locations only.

(h) Exceptions to SASB 737-53-1168, Revision 4

    (1) Where SASB 737-53-1168, Revision 4, specifies compliance 
times ``after the Revision 4 date of this service bulletin,'' this 
AD requires compliance within the specified compliance times after 
the effective date of this AD.
    (2) The Condition column of paragraph 1.E., ``Compliance,'' of 
SASB 737-53-1168, Revision 4, refers to airplanes in certain 
configurations as of the ``issue date of Revision 4 of this service 
bulletin.'' However, this AD applies to airplanes in the specified 
configurations ``as of the effective date of this AD.''
    (3) Where SASB 737-53-1168, Revision 4, specifies contacting 
Boeing for repair instructions or work instructions, before further 
flight, repair or perform the work instructions using a method 
approved in accordance with the procedures specified in paragraph 
(n) of this AD, except as required by paragraph (h)(4) of this AD.
    (4) For airplanes on which an operator has a record that a skin 
panel was replaced with a production skin panel before 53,000 total 
flight cycles: At the applicable time for the next inspection as 
specified in tables 1 and 2 of paragraph 1.E., ``Compliance,'' of 
SASB 737-53-1168, Revision 4, except as provided by paragraph (h)(1) 
and (h)(2) of this AD, perform inspections and applicable corrective 
actions using a method approved in accordance with the procedures 
specified in paragraph (n) of this AD.

(i) Actions for Airplanes With a Time-Limited Repair Installed

    (1) For airplanes with a time-limited repair installed, as 
specified in Boeing Service Bulletin 737-53-1168, Revision 3, dated 
November 28, 2006: At the applicable times specified in table 3 of 
paragraph 1.E., ``Compliance,'' of SASB 737-53-1168, Revision 4, 
except as provided by paragraphs (h)(1) and (h)(2) of this AD, do 
the actions specified in paragraphs (i)(1)(i) and (i)(1)(ii) of this 
AD.
    (i) Do the applicable inspections to detect missing or loose 
fasteners and any disbonding or cracking of bonded doublers, and do 
all applicable related investigative and corrective actions, in 
accordance with the Accomplishment Instructions of SASB 737-53-1168, 
Revision 4, except as required by paragraph (h)(3) of this AD. Do 
all applicable related investigative and corrective actions before 
further flight. Repeat the applicable inspections thereafter at the 
applicable intervals specified in SASB 737-53-1168, Revision 4.
    (ii) Make the time-limited repair permanent, and do all 
applicable related investigative and corrective actions, in 
accordance with Part 6 of the Accomplishment Instructions of SASB 
737-53-1168, Revision 4, except as required by paragraph (h)(3) of 
this AD. Do all applicable related investigative and corrective 
actions before further flight. Accomplishing the permanent repair 
required by this paragraph terminates the inspections required by 
paragraph (i)(1)(i) of this AD for the permanently repaired area 
only.
    (2) For airplanes with a time-limited repair installed, as 
specified in SASB 737-53-1168, Revision 4: At the applicable times 
specified in table 4 of paragraph 1.E., ``Compliance,'' of SASB 737-
53-1168, Revision 4, do the actions specified in paragraphs 
(i)(2)(i) and (i)(2)(ii) of this AD.
    (i) Do the applicable inspections to detect missing or loose 
fasteners and any disbonding or cracking of bonded doublers, and do 
all applicable related investigative and corrective actions, in 
accordance with the Accomplishment Instructions of SASB 737-53-1168, 
Revision 4, except as required by paragraph (h)(3) of this AD. Do 
all applicable related investigative and corrective actions before 
further flight. Repeat the applicable inspections thereafter at the 
applicable intervals specified in table 4 of paragraph 1.E., 
``Compliance,'' of SASB 737-53-1168, Revision 4.
    (ii) Make the time-limited repair permanent, and do all 
applicable related investigative and corrective actions, in 
accordance with Part 6 of the Accomplishment Instructions of SASB 
737-53-1168, Revision 4, except as required by paragraph (h)(3) of 
this AD. Do all applicable related investigative and corrective 
actions before further flight. Accomplishing the permanent repair 
required by this paragraph terminates the inspections required by 
paragraph (i)(2)(i) of this AD for the permanently repaired area 
only.

(j) Modification of Certain Permanent Repairs

    For airplanes with an existing time-limited repair that was made 
permanent, as specified in Boeing Service Bulletin 737-53-1168, 
Revision 3, dated November 28, 2006: At the applicable times 
specified in table 5 of paragraph 1.E., ``Compliance,'' of SASB 737-
53-1168, Revision 4, except as provided by paragraphs (h)(1) of this 
AD, modify the existing permanent repair, and do all applicable 
related investigative and corrective actions, in accordance with 
Part 6 of the Accomplishment Instructions of SASB 737-53-1168, 
Revision 4, except as required

[[Page 24472]]

by paragraph (h)(3) of this AD. Do all applicable related 
investigative and corrective actions before further flight.

(k) Post-Repair Inspections

    Table 6 of paragraph 1.E., ``Compliance,'' of SASB 737-53-1168, 
Revision 4, specifies post-repair airworthiness limitation 
inspections in compliance with 14 CFR 25.571(a)(3) at the repaired 
locations, which support compliance with 14 CFR 121.1109(c)(2) or 
129.109(b)(2). As airworthiness limitations, these inspections are 
required by maintenance and operational rules. It is therefore 
unnecessary to mandate them in this AD. Deviations from these 
inspections require FAA approval, but do not require an AMOC.

(l) Skin Panel Replacement

    At the later of the times specified in paragraphs (l)(1), 
(1)(2), and (l)(3) of this AD: Replace the applicable skin panels, 
and do all applicable related investigative and corrective actions, 
in accordance with the Accomplishment Instructions of SASB 737-53-
1168, Revision 4. Do all applicable related investigative and 
corrective actions before further flight. Doing the skin panel 
replacement required by this paragraph terminates the inspection 
requirements of paragraphs (g), (i), and (j) of this AD for that 
skin panel only, provided the skin panel replacement was done with a 
production skin panel after 53,000 total flight cycles.
    (1) Before 60,000 total flight cycles, but not before 53,000 
total flight cycles.
    (2) Within 6,000 flight cycles after the effective date of this 
AD, but not before 53,000 total flight cycles.
    (3) If the skin panel is replaced with a production skin panel, 
not before 53,000 total flight cycles. If the skin panel is replaced 
with a kit skin panel as specified in SASB 737-53-1168, Revision 4, 
the 53,000 total flight cycle limit does not apply.

(m) 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 Boeing Service Bulletin 737-53-1168, 
Revision 3, dated November 28, 2006, except as required by paragraph 
(h)(4) of this AD. Boeing Service Bulletin 737-53-1168, Revision 3, 
dated November 28, 2006, was incorporated by reference in AD 2009-
21-01.
    (2) This paragraph provides credit for the actions required by 
paragraph (l) of this AD, if those actions were performed before the 
effective date of this AD using Boeing Service Bulletin 737-53-1168, 
Revision 3, dated November 28, 2006, except as required by paragraph 
(h)(4) of this AD. Boeing Service Bulletin 737-53-1168, Revision 3, 
dated November 28, 2006, was incorporated by reference in AD 2009-
21-01.
    (3) This paragraph provides credit for the actions required by 
paragraph (l) of this AD, if those actions were performed before 
November 17, 2009 (the effective date of AD 2009-21-01), using any 
service information specified in paragraphs (m)(3)(i), (m)(3)(ii), 
and (m)(3)(iii) of this AD, provided the replacement is made with a 
kit skin panel, except as required by paragraph (h)(4) of this AD. 
The service information specified in paragraphs (m)(3)(i), 
(m)(3)(ii), and (m)(3)(iii) of this AD was incorporated by reference 
in AD 2009-21-01.
    (i) Part 3 of the Accomplishment Instructions of Boeing Service 
Bulletin 737-53-1168, dated March 16, 1995.
    (ii) Part 3 of the Accomplishment Instructions of Boeing Service 
Bulletin 737-53-1168, Revision 1, dated August 17, 1995.
    (iii) Part 3 of the Accomplishment Instructions of Boeing 
Service Bulletin 737-53-1168, Revision 2, dated November 27, 1996.

(n) 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 (o)(1) of this AD. 
Information may be emailed to: [email protected].
    (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, 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) AMOCs approved previously for repairs required by AD 2009-
21-01 are approved as AMOCs for the corresponding provisions of 
paragraph (g) of this AD.
    (5) AMOCs approved previously for modifications done as optional 
terminating action for AD 2009-21-01 are approved as AMOCs for the 
skin panel replacement required by paragraph (l) of this AD.

(o) Related Information

    (1) For more information about this AD, contact Jennifer 
Tsakoumakis, Aerospace Engineer, Airframe Branch, ANM-120L, FAA, Los 
Angeles ACO, 3960 Paramount Boulevard, Lakewood, CA 90712-4137; 
phone: 562-627-5264; fax: 562-627-5210; email: 
[email protected].
    (2) Service information identified in this AD that is not 
incorporated by reference is available at the addresses specified in 
paragraphs (p)(3) and (p)(4) of this AD.

(p) 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 Special Attention Service Bulletin 737-53-1168, 
Revision 4, dated June 3, 2015.
    (ii) Reserved.
    (3) For Boeing 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 
90740-5600; 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 2, 2017.
Michael Kaszycki,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2017-10288 Filed 5-26-17; 8:45 am]
 BILLING CODE 4910-13-P