[Federal Register Volume 81, Number 93 (Friday, May 13, 2016)]
[Proposed Rules]
[Pages 29802-29807]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2016-11170]


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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]
RIN 2120-AA64


Airworthiness Directives; The Boeing Company Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: We propose to supersede Airworthiness Directive (AD) 2009-21-
01, which applies to certain Boeing Model 737-300 and 737-400 series 
airplanes. AD 2009-21-01 currently requires repetitive inspections to 
detect cracking of the aft fuselage skin, and related investigative and 
corrective actions if necessary. Since we issued AD 2009-21-01, an 
evaluation by the design approval holder (DAH) indicates that the aft 
fuselage skin is subject to widespread fatigue damage (WFD). This 
proposed AD would 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 proposed AD also removes Model 737-400 series 
airplanes from the applicability. We are proposing this AD to detect 
and correct cracking in the aft fuselage skin along the longitudinal 
edges of the bonded skin doubler, which could result in possible rapid 
decompression and reduced structural integrity of the airplane.

DATES: We must receive comments on this proposed AD by June 27, 2016.

[[Page 29803]]


ADDRESSES: You may send comments, using the procedures found in 14 CFR 
11.43 and 11.45, by any of the following methods:
     Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the instructions for submitting comments.
     Fax: 202-493-2251.
     Mail: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue SE., Washington, DC 20590.
     Hand Delivery: Deliver to Mail address above between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
    For service information identified in this NPRM, 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-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 proposed AD, the regulatory evaluation, any comments 
received, and other information. The street address for the Docket 
Office (phone: 800-647-5527) is in the ADDRESSES section. Comments will 
be available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT: Wade Sullivan, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office 
(ACO), 1601 Lind Avenue SW., Renton, WA 98057-3356; phone: 425-917-
6430; fax: 425-917-6590; email: [email protected].

SUPPLEMENTARY INFORMATION:

Comments Invited

    We invite you to send any written relevant data, views, or 
arguments about this proposed AD. Send your comments to an address 
listed under the ADDRESSES section. Include ``Docket No. FAA-2016-6667; 
Directorate Identifier 2015-NM-125-AD'' at the beginning of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of this proposed AD. We 
will consider all comments received by the closing date and may amend 
this proposed AD because of those comments.
    We will post all comments we receive, without change, to http://www.regulations.gov, including any personal information you provide. We 
will also post a report summarizing each substantive verbal contact we 
receive about this proposed AD.

Discussion

    Fatigue damage can occur locally, in small areas or structural 
design details, or globally, in widespread areas. Multiple-site damage 
is widespread damage that occurs in a large structural element such as 
a single rivet line of a lap splice joining two large skin panels. 
Widespread damage can also occur in multiple elements such as adjacent 
frames or stringers. Multiple-site damage and multiple-element damage 
cracks are typically too small initially to be reliably detected with 
normal inspection methods. Without intervention, these cracks will 
grow, and eventually compromise the structural integrity of the 
airplane. This condition is known as widespread fatigue damage. It is 
associated with general degradation of large areas of structure with 
similar structural details and stress levels. As an airplane ages, WFD 
will likely occur, and will certainly occur if the airplane is operated 
long enough without any intervention.
    The FAA's WFD final rule (75 FR 69746, November 15, 2010) became 
effective on January 14, 2011. The WFD rule requires certain actions to 
prevent structural failure due to WFD throughout the operational life 
of certain existing transport category airplanes and all of these 
airplanes that will be certificated in the future. For existing and 
future airplanes subject to the WFD rule, the rule requires that DAHs 
establish a limit of validity (LOV) of the engineering data that 
support the structural maintenance program. Operators affected by the 
WFD rule may not fly an airplane beyond its LOV, unless an extended LOV 
is approved.
    The WFD rule (75 FR 69746, November 15, 2010) does not require 
identifying and developing maintenance actions if the DAHs can show 
that such actions are not necessary to prevent WFD before the airplane 
reaches the LOV. Many LOVs, however, do depend on accomplishment of 
future maintenance actions. As stated in the WFD rule, any maintenance 
actions necessary to reach the LOV will be mandated by airworthiness 
directives through separate rulemaking actions.
    In the context of WFD, this action is necessary to enable DAHs to 
propose LOVs that allow operators the longest operational lives for 
their airplanes, and still ensure that WFD will not occur. This 
approach allows for an implementation strategy that provides 
flexibility to DAHs in determining the timing of service information 
development (with FAA approval), while providing operators with 
certainty regarding the LOV applicable to their airplanes.
    On September 25, 2009, we issued AD 2009-21-01, Amendment 39-16038 
(74 FR 52395, October 13, 2009) (``AD 2009-21-01''), for certain Boeing 
Model 737-300 and 737-400 series airplanes. AD 2009-21-01 requires 
repetitive inspections to detect cracking of the aft fuselage skin, and 
related investigative and corrective actions if necessary. AD 2009-21-
01 resulted from reports of cracks in the aft fuselage skin on both 
sides of the airplane. We issued AD 2009-21-01 to detect and correct 
cracking in the aft fuselage skin along the longitudinal edges of the 
bonded skin doubler, which could result in reduced structural integrity 
of the airplane.

Actions Since AD 2009-21-01 Was Issued

    Since we issued AD 2009-21-01, additional cracks have been found on 
airplanes in the skin panels from station 727 to station 1016 and from 
stringer S-14 to stringer S-25 on the left and right sides of the 
airplanes. Cracks at fastener holes in the bonded doubler have also 
been reported on several airplanes in the area above stringer S-17 on 
the left and right side of the airplanes.
    An evaluation by the DAH indicates that the aft fuselage skin is 
subject to WFD. On the existing skin panel assemblies, the doubler is 
chemically milled to create pockets of various depths. At these skin 
panel locations on the airplane, the loads could cause a condition 
where cracks could form along the longitudinal edges of the doubler.
    AD 2009-21-01 applies to certain Boeing Model 737-300 and 737-400 
series airplanes. This proposed AD is applicable to certain Model 737-
300 series airplanes. We are considering issuing additional rulemaking 
that will apply to Model 737-400 series airplanes. We have determined 
that, in

[[Page 29804]]

this case, a less burdensome approach is to issue separate ADs 
applicable only to each model type.

Related Service Information Under 1 CFR Part 51

    We reviewed Boeing Special Attention Service Bulletin 737-53-1168, 
Revision 4, dated June 3, 2015. 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.

FAA's Determination

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

Proposed AD Requirements

    Although this proposed AD does not explicitly restate the 
requirements of AD 2009-21-01, this proposed AD would retain all of the 
requirements of AD 2009-21-01 for Model 737-300 series airplanes, 
except the skin panel replacement is terminating action only if the 
skin panel replacement is done with a production skin panel after 
53,000 total flight cycles. Those requirements are referenced in the 
service information identified previously, which, in turn, is 
referenced in paragraphs (g) and (h) of this proposed AD. This proposed 
AD would require accomplishing the actions specified in the service 
information described previously, except as discussed under 
``Differences Between this Proposed AD and the Service Information.'' 
For information on the procedures and compliance times, see this 
service information at http://www.regulations.gov by searching for and 
locating Docket No. FAA-2016-6667.
    The phrase ``related investigative actions'' is used in this 
proposed AD. ``Related investigative actions'' are follow-on actions 
that (1) are related to the primary action, and (2) further investigate 
the nature of any condition found. Related investigative actions in an 
AD could include, for example, inspections.
    The phrase ``corrective actions'' is used in this proposed AD. 
``Corrective actions'' are actions that correct or address any 
condition found. Corrective actions in an AD could include, for 
example, repairs.

Differences Between This Proposed AD and the Service Information

    Boeing Special Attention Service Bulletin 737-53-1168, Revision 4, 
dated June 3, 2015, specifies to contact the manufacturer for 
instructions on how to repair certain conditions and also to obtain 
certain work instructions, but this proposed AD would require repairing 
those conditions and also to obtain those work instructions in one of 
the following ways:
     In accordance with a method that we approve; or
     Using data that meet the certification basis of the 
airplane, and that have been approved by the Boeing Commercial 
Airplanes Organization Designation Authorization (ODA) whom we have 
authorized to make those findings.
    Table 6 of paragraph 1.E., ``Compliance,'' of Boeing Special 
Attention Service Bulletin 737-53-1168, Revision 4, dated June 3, 2015, 
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 alternative method of compliance. This 
difference has been coordinated with Boeing.

Explanation of Compliance Time

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

Costs of Compliance

    We estimate that this proposed AD affects 168 airplanes of U.S. 
registry.
    We estimate the following costs to comply with this proposed AD:

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
          Action                  Labor cost         Parts cost  Cost per product      Cost on U.S. operators
----------------------------------------------------------------------------------------------------------------
Inspections...............  Up to 1,791                      $0  Up to $152,235..  Up to $25,575,480.
                             work[dash]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 proposed 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 hour =             [\1\]   $2,040 per repair.
                                       $2,040 per repair.
Permanent repair....................  Up to 43 work[dash]hours x $85             [\1\]   Up to $3,655 per
                                       per hour = $3,655 per repair.                      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 proposed 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:

[[Page 29805]]



                                          Post-Repair Inspection Costs
----------------------------------------------------------------------------------------------------------------
               Action                            Labor cost                Parts cost        Cost per product
----------------------------------------------------------------------------------------------------------------
Post-repair inspection..............  Up to 7 work[dash]hours x $85                 $0   Up to $595.
                                       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 proposed AD would not have federalism 
implications under Executive Order 13132. This proposed AD would not 
have a substantial direct effect on the States, on the relationship 
between the national Government and the States, or on the distribution 
of power and responsibilities among the various levels of government.
    For the reasons discussed above, I certify that the proposed 
regulation:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866,
    (2) Is not a ``significant rule'' under the DOT Regulatory Policies 
and Procedures (44 FR 11034, February 26, 1979),
    (3) Will not affect intrastate aviation in Alaska, and
    (4) Will not have a significant economic impact, positive or 
negative, on a substantial number of small entities under the criteria 
of the Regulatory Flexibility Act.

List of Subjects in 14 CFR Part 39

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

The Proposed Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA proposes to amend 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

0
1. The authority citation for part 39 continues to read as follows:

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


Sec.  39.13  [Amended]

0
2. The FAA amends Sec.  39.13 by removing Airworthiness Directive (AD) 
2009-21-01, Amendment 39-16038 (74 FR 52395, October 13, 2009), and 
adding the following new AD:

The Boeing Company: Docket No. FAA-2016-6667; Directorate Identifier 
2015-NM-125-AD.

(a) Comments Due Date

    The FAA must receive comments on this AD action by June 27, 
2016.

(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

    This AD applies to Boeing 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.

(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) indicates that the aft fuselage skin is subject to 
widespread fatigue damage (WFD). We are issuing this AD to detect 
and correct cracking in the aft fuselage skin along the longitudinal 
edges of 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 Boeing Special Attention Service Bulletin 
737-53-1168, Revision 4, dated June 3, 2015, except as required by 
paragraph (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 Boeing Special 
Attention Service Bulletin 737-53-1168, Revision 4, dated June 3, 
2015, 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 Boeing Special Attention Service Bulletin 
737-53-1168, Revision 4, dated June 3, 2015. Accomplishment of a 
repair in accordance with ``Part 4: Repair'' of the Accomplishment 
Instructions of Boeing Special Attention Service Bulletin 737-53-
1168, Revision 4, dated June 3, 2015, 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 Boeing Special Attention Service Bulletin 737-53-
1168, Revision 4, Dated June 3, 2015

    (1) Where Boeing Special Attention Service Bulletin 737-53-1168, 
Revision 4, dated June 3, 2015, 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 
Boeing Special Attention Service Bulletin 737-53-1168, Revision 4, 
dated June 3, 2015, 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 Boeing Special Attention Service Bulletin 737-53-1168, 
Revision 4, dated June 3, 2015, 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,'' 
Boeing Special Attention Service Bulletin 737-53-1168, Revision 4, 
dated June 3, 2015, 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 Boeing Special Attention

[[Page 29806]]

Service Bulletin 737-53-1168, Revision 4, dated June 3, 2015, 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 Boeing Special 
Attention Service Bulletin 737-53-1168, Revision 4, dated June 3, 
2015, 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 Boeing Special Attention Service 
Bulletin 737-53-1168, Revision 4, dated June 3, 2015.
    (ii) Make the time limited repair permanent; and do all 
applicable related investigative and corrective actions; in 
accordance with the Accomplishment Instructions of Boeing Special 
Attention Service Bulletin 737-53-1168, Revision 4, dated June 3, 
2015, 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 Boeing Special Attention Service Bulletin 737-53-1168, 
Revision 4, dated June 3, 2015: At the applicable times specified in 
table 4 of paragraph 1.E., ``Compliance,'' of Boeing Special 
Attention Service Bulletin 737-53-1168, Revision 4, dated June 3, 
2015: 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 Boeing Special 
Attention Service Bulletin 737-53-1168, Revision 4, dated June 3, 
2015, 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 Boeing Special Attention Service Bulletin 737-53-
1168, Revision 4, dated June 3, 2015.
    (ii) Make the time limited repair permanent; and do all 
applicable related investigative and corrective actions; in 
accordance with the Accomplishment Instructions of Boeing Special 
Attention Service Bulletin 737-53-1168, Revision 4, dated June 3, 
2015, 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 Boeing 
Special Attention Service Bulletin 737-53-1168, Revision 4, dated 
June 3, 2015, 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 the 
Accomplishment Instructions of Boeing Special Attention Service 
Bulletin 737-53-1168, Revision 4, dated June 3, 2015, except as 
required 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 Boeing Service 
Bulletin Special Attention Service Bulletin 737-53-1168, Revision 4, 
dated June 3, 2015, 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 alternative 
method of compliance.

(l) Skin Panel Replacement

    At the later of the times specified in paragraphs (l)(1) and 
(1)(2) of this AD: Replace the applicable skin panels, and do all 
applicable related investigative and corrective actions, in 
accordance with the Accomplishment Instructions of Boeing Special 
Attention Service Bulletin 737-53-1168, Revision 4, dated June 3, 
2015. 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.

(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; provided the skin panel replacement was done with 
a production skin panel after 53,000 total flight cycles. 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, except as required by paragraph (h)(4) 
of this AD; provided the skin panel replacement was done with a 
production skin panel after 53,000 total flight cycles. The service 
information specified in paragraphs (m)(3)(i), (m)(3)(ii), and 
(m)(3)(iii) of this AD are not incorporated by reference in this AD.
    (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, 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 (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 for AD 2009-21-01 are 
approved as AMOCs for the corresponding provisions of paragraph (g) 
of this AD.
    (5) AMOCs approved for previous modifications done as optional 
terminating action for AD 2009-21-01 are approved as AMOCs for the 
modification required by paragraph (l) of this AD provided the 
previous modification was done after the

[[Page 29807]]

airplane had accumulated 53,000 total flight cycles or more.

(o) Related Information

    (1) For more information about this AD, contact Wade Sullivan, 
Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle ACO, 
1601 Lind Avenue SW., Renton, WA 98057-3356; phone: 425-917-6430; 
fax: 425-917-6590; email: [email protected].
    (2) For service information identified in this AD, contact 
Boeing Commercial Airplanes, Attention: Data & Services Management, 
P.O. Box 3707, MC 2H-65, Seattle, WA 98124-2207; telephone: 206-544-
5000, extension 1; fax: 206-766-5680; Internet: https://www.myboeingfleet.com. You may view this referenced service 
information at the FAA, Transport Airplane Directorate, 1601 Lind 
Avenue SW., Renton, WA. For information on the availability of this 
material at the FAA, call 425-227-1221.

    Issued in Renton, Washington, on May 4, 2016.
Michael Kaszycki,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2016-11170 Filed 5-12-16; 8:45 am]
 BILLING CODE 4910-13-P