[Federal Register Volume 80, Number 228 (Friday, November 27, 2015)]
[Proposed Rules]
[Pages 74047-74052]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2015-30008]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2015-5812; Directorate Identifier 2015-NM-077-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) 2011-23-
05, which applies to certain The Boeing Company Model 737-300, -400, 
and -500 series airplanes. AD 2011-23-05 currently requires repetitive 
inspections for cracking of the 1.04-inch nominal diameter wire 
penetration hole, and applicable related investigative and corrective 
actions. Since we issued AD 2011-23-05, an evaluation by the design 
approval holder (DAH) indicates that the fuselage frames and frame 
reinforcements are subject to widespread fatigue damage (WFD). This 
proposed AD would add new inspection areas, a modification that 
terminates certain inspections, post-modification inspections, and 
repair if necessary. We are proposing this AD to detect and correct 
fatigue cracking of the fuselage frames and frame reinforcements, which 
could result in reduced structural integrity of the airplane.

DATES: We must receive comments on this proposed AD by January 11, 
2016.

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 proposed AD, contact 
Boeing Commercial Airplanes, Attention: Data & Services Management, P. 
O. Box 3707, MC 2H-65, Seattle, WA 98124-2207; telephone 206-544-5000, 
extension 1; fax 206-766-5680; Internet https://www.myboeingfleet.com. 
You may view this referenced service information at the FAA, Transport 
Airplane Directorate, 1601 Lind Avenue SW., Renton, Washington. 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-2015-
5812.

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-2015-
5812; or in person at the Docket Management Facility between 9 a.m. and 
5 p.m., Monday through Friday, except Federal holidays. The AD docket 
contains this proposed AD, the regulatory evaluation, any comments 
received, and other information. The street address for the Docket 
Office (phone: 800-647-5527) is in the ADDRESSES section. Comments will 
be available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT: Wayne Lockett, Aerospace Engineer,

[[Page 74048]]

Airframe Branch, ANM-120S, Seattle Aircraft Certification Office (ACO), 
FAA, 1601 Lind Avenue SW., Renton, Washington 98057-3356; phone: 425-
917-6447; 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-2015-5812; 
Directorate Identifier 2015-NM-077-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

    Structural fatigue damage is progressive. It begins as minute 
cracks, and those cracks grow under the action of repeated stresses. 
This can happen because of normal operational conditions and design 
attributes, or because of isolated situations or incidents such as 
material defects, poor fabrication quality, or corrosion pits, dings, 
or scratches. Fatigue damage can occur locally, in small areas or 
structural design details, or globally. Global fatigue damage is 
general degradation of large areas of structure with similar structural 
details and stress levels. Multiple-site damage is global damage that 
occurs in a large structural element such as a single rivet line of a 
lap splice joining two large skin panels. Global damage can also occur 
in multiple elements such as adjacent frames or stringers. Multiple-
site-damage and multiple-element-damage cracks are typically too small 
initially to be reliably detected with normal inspection methods. 
Without intervention, these cracks will grow, and eventually compromise 
the structural integrity of the airplane, in a condition known as WFD. 
As an airplane ages, WFD will likely occur, and will certainly occur if 
the airplane is operated long enough without any intervention.
    The FAA's WFD final rule (75 FR 69746, November 15, 2010) became 
effective on January 14, 2011. The WFD rule requires certain actions to 
prevent structural failure due to WFD throughout the operational life 
of certain existing transport category airplanes and all of these 
airplanes that will be certificated in the future. For existing and 
future airplanes subject to the WFD rule, the rule requires that 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 October 20, 2011, we issued AD 2011-23-05, Amendment 39-16856 
(76 FR 67343, November 1, 2011), for certain Model 737-300, -400, and -
500 series airplanes. AD 2011-23-05 superseded AD 2009-02-06 R1, 
Amendment 39-16015 (74 FR 45979, September 8, 2009). AD 2011-23-05 
requires repetitive inspections for cracking of the 1.04-inch nominal 
diameter wire penetration hole, and applicable related investigative 
and corrective actions. AD 2011-23-05 resulted from reports of cracking 
in the frame, or in the frame and frame reinforcement, common to the 
1.04-inch nominal diameter wire penetration hole intended for wire 
routing; and recent reports of multiple adjacent frame cracking found 
before the compliance time required by AD 2009-02-06 R1. We issued AD 
2011-23-05 to detect and correct cracking in the fuselage frames and 
frame reinforcements, which could reduce the structural capability of 
the frames to sustain limit loads, and result in cracking in the 
fuselage skin and subsequent rapid depressurization of the airplane.

Actions Since AD 2011-23-05, Amendment 39-16856 (76 FR 67343, November 
1, 2011), Was Issued

    Since we issued AD 2011-23-05, Amendment 39-16856 (76 FR 67343, 
November 1, 2011), an evaluation by the DAH indicates that the fuselage 
frames and frame reinforcements are subject to WFD.

Related Service Information Under 1 CFR Part 51

    We reviewed Boeing Alert Service Bulletin 737-53A1279, Revision 2, 
dated April 21, 2015. The service information describes procedures for 
the following actions.
     Inspections of wire penetration holes, standoff/tooling 
holes, and the production fastener holes for cracking in the forward 
cargo compartment frames and frame reinforcements, between stringer (S) 
S-19 and S-22, on both left and right sides of the airplane.
     A preventive modification of frames between S-19 and S-22.
     Post-modification inspections.
     Repairs.
    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 
NPRM.

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 these same type 
designs.

Proposed AD Requirements

    This proposed AD would retain all requirements of AD 2011-23-05, 
Amendment 39-16856 (76 FR 67343, November 1, 2011). 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-2015-5812.

Differences Between This Proposed AD and the Service Information

    Boeing Alert Service Bulletin 737-53A1279, Revision 2, dated April 
21, 2015, specifies to contact the manufacturer for instructions on how 
to

[[Page 74049]]

repair certain conditions, but this proposed AD would require repairing 
those conditions 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.

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

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                                                 Cost on U.S.
              Action                    Labor cost        Parts cost      Cost per product        operators
----------------------------------------------------------------------------------------------------------------
Inspections [retained actions      16 work-hours x $85              $0  $1,360 per           $822,800 per
 from AD 2011-23-05, Amendment 39-  per hour = $1,360                    inspection cycle.    inspection cycle.
 16856 (76 FR 67343, November 1,    per inspection
 2011).                             cycle.
Inspections [new proposed action]  32 work-hours x $85               0  $2,720 per           $1,645,600 per
                                    per hour = $2,720                    inspection cycle.    inspection cycle.
                                    per inspection
                                    cycle.
Modification [new proposed         32 work-hours x $85               0  $2,720.............  $1,645,600.
 action].                           per hour = $2,720.
----------------------------------------------------------------------------------------------------------------

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

                                               On-Condition Costs
----------------------------------------------------------------------------------------------------------------
                                                                                                     Cost per
                Action                            Labor cost                   Parts cost             product
----------------------------------------------------------------------------------------------------------------
Repair................................  18 work-hours x $85 per hour =  None....................          $1,530
                                         $1,530.
----------------------------------------------------------------------------------------------------------------

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) 
2011-23-05, Amendment 39-16856 (76 FR 67343, November 1, 2011), and 
adding the following new AD:

The Boeing Company: Docket No. FAA-2015-5812; Directorate Identifier 
2015-NM-077-AD.

(a) Comments Due Date

    The FAA must receive comments on this AD action by January 11, 
2016.

(b) Affected ADs

    This AD replaces AD 2011-23-05, Amendment 39-16856 (76 FR 67343, 
November 1, 2011).

(c) Applicability

    This AD applies to The Boeing Company Model 737-300, -400, and -
500 series airplanes; certificated in any category; as identified in 
Boeing Alert Service Bulletin 737-53A1279, Revision 2, dated April 
21, 2015.

[[Page 74050]]

(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 fuselage frames and frame 
reinforcements are subject to widespread fatigue damage (WFD). We 
are issuing this AD to detect and correct fatigue cracking of the 
fuselage frames and frame reinforcements, which could result in 
reduced structural integrity of the airplane.

(f) Compliance

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

(g) Retained Inspection, With References To Terminating Actions

    This paragraph restates the requirements of paragraph (g) of AD 
2011-23-05, Amendment 39-16856 (76 FR 67343, November 1, 2011), with 
references to terminating actions. At the applicable time specified 
in paragraph 1.E., ``Compliance,'' of Boeing Alert Service Bulletin 
737-53A1279, Revision 1, dated September 2, 2011, except as required 
by paragraphs (k)(1), (k)(2), and (k)(4) of this AD: Do a high 
frequency eddy current (HFEC) surface or HFEC hole/edge inspection 
for any cracking of the 1.04-inch nominal diameter wire penetration 
hole in the frame and frame reinforcement between stringer (S) S-20 
and S-21, in accordance with Part 2 of the Accomplishment 
Instructions of Boeing Alert Service Bulletin 737-53A1279, Revision 
1, dated September 2, 2011. Accomplishment of the applicable 
inspections required by paragraphs (m) and (n) of this AD terminates 
the inspections required by this paragraph. Accomplishment of the 
modification required by paragraph (p) of this AD terminates the 
inspections required by this paragraph for the modified area only.

(h) Retained Repetitive Inspections, With References To Terminating 
Actions

    This paragraph restates the requirements of paragraph (h) of AD 
2011-23-05, Amendment 39-16856 (76 FR 67343, November 1, 2011), with 
references to terminating actions. Within 4,500 flight cycles after 
accomplishment of the most recent inspection specified in Part 2 or 
Part 4 of the Accomplishment Instructions of Boeing Alert Service 
Bulletin 737-53A1279, Revision 1, dated September 2, 2011, or within 
90 days after November 16, 2011 (the effective date of AD 2011-23-
05), whichever occurs later: Do an HFEC hole/edge inspection for 
cracking of the 1.04-inch nominal diameter wire penetration hole in 
the frame and frame reinforcement between S-20 and S-21, in 
accordance with Part 4 of the Accomplishment Instructions of Boeing 
Alert Service Bulletin 737-53A1279, Revision 1, dated September 2, 
2011. Repeat the inspection thereafter at intervals not to exceed 
4,500 flight cycles. Accomplishment of the applicable inspections 
required by paragraphs (m) and (n) of this AD, terminates the 
inspections required by this paragraph. Accomplishment of the 
modification specified in paragraph (j) or (p) of this AD terminates 
the repetitive inspections required by this paragraph for the 
modified area only. Accomplishment of the repair specified in 
paragraph (i) of this AD terminates the repetitive inspections 
required by this paragraph for the repaired area only.

(i) Retained Repair, With No Changes

    This paragraph restates the requirements of paragraph (i) of AD 
2011-23-05, Amendment 39-16856 (76 FR 67343, November 1, 2011), with 
no changes. If any cracking is found during any inspection required 
by paragraph (g) or (h) of this AD: Before further flight, repair 
the crack including doing all applicable related investigative and 
corrective actions, in accordance with the Accomplishment 
Instructions of Boeing Alert Service Bulletin 737-53A1279, Revision 
1, dated September 2, 2011, except as required by paragraph (k)(3) 
of this AD. All applicable related investigative and corrective 
actions must be done before further flight. Accomplishment of the 
requirements of this paragraph terminates the repetitive inspection 
requirements of paragraph (h) of this AD for the repaired location 
of that frame.

(j) Retained Optional Terminating Action, With New Limitation

    This paragraph restates the optional action provided in 
paragraph (j) of AD 2011-23-05, Amendment 39-16856 (76 FR 67343, 
November 1, 2011), with new limitation. Accomplishment of the 
preventive modification before the effective date of this AD, 
including doing all related investigative and applicable corrective 
actions, specified in Part 5 of the Accomplishment Instructions of 
Boeing Alert Service Bulletin 737-53A1279, Revision 1, dated 
September 2, 2011, except as required by paragraph (k)(3) of this 
AD, terminates the repetitive inspection requirements of paragraph 
(h) of this AD for the modified location of that frame, provided the 
modification is done before further flight after an inspection 
required by paragraph (g) or (h) of this AD has been done, and no 
cracking was found on that frame location during that inspection.

(k) Retained Exceptions to Service Information Specifications, With No 
Changes

    This paragraph restates the requirements of paragraph (k) of AD 
2011-23-05, Amendment 39-16856 (76 FR 67343, November 1, 2011), with 
no changes. The following exceptions apply as specified in 
paragraphs (g), (i), and (j) of this AD.
    (1) Where paragraph 1.E., ``Compliance,'' of Boeing Alert 
Service Bulletin 737-53A1279, Revision 1, dated September 2, 2011, 
refers to a compliance time ``from date on Revision 1 of this 
service bulletin,'' this AD requires compliance within the specified 
compliance time after November 16, 2011 (the effective date of AD 
2011-23-05, Amendment 39-16856 (76 FR 67343, November 1, 2011)).
    (2) For airplanes meeting all of the criteria specified in 
paragraphs (k)(2)(i), (k)(2)(ii), and (k)(2)(iii) of this AD: The 
compliance time for the initial inspection specified in Part 2 of 
the Accomplishment Instructions of Boeing Alert Service Bulletin 
737-53A1279, Revision 1, dated September 2, 2011, and required by 
paragraph (g) of this AD, may be extended to 90 days after November 
16, 2011 (the effective date of AD 2011-23-05, Amendment 39-16856 
(76 FR 67343, November 1, 2011)).
    (i) Model 737-300 series airplanes in Group 1, line numbers 1001 
through 2565 inclusive;
    (ii) Airplanes that have accumulated 40,000 or more total flight 
cycles as of November 16, 2011 (the effective date of AD 2011-23-05, 
Amendment 39-16856 (76 FR 67343, November 1, 2011)); and
    (iii) Airplanes on which the modification specified in Boeing 
Service Bulletin 737-53-1273, dated September 20, 2006; Revision 1, 
dated December 21, 2006; Revision 2, dated June 4, 2007; Revision 3, 
dated December 7, 2009; or Revision 4, dated July 23, 2010; has been 
done, including any configuration or deviation that has been 
approved as an AMOC during accomplishment of these service 
bulletins, by the Boeing Commercial Airplanes Organization 
Designation Authorization (ODA) that has been authorized by the 
Manager, Seattle Aircraft Certification Office (ACO) to make those 
findings.
    (3) Where Boeing Alert Service Bulletin 737-53A1279, Revision 1, 
dated September 2, 2011, specifies to contact Boeing for appropriate 
repair instructions: Before further flight, repair the crack using a 
method approved in accordance with the procedures specified in 
paragraph (u) of this AD.
    (4) The ``Condition'' column of paragraph 1.E., ``Compliance,'' 
of Boeing Alert Service Bulletin 737-53A1279, Revision 1, dated 
September 2, 2011, refers to total flight cycles ``at the date of/on 
this service bulletin.'' However, this AD applies to the airplanes 
with the specified total flight cycles as of November 16, 2011 (the 
effective date of AD 2011-23-05, Amendment 39-16856 (76 FR 67343, 
November 1, 2011)).

(l) Retained Credit for Previous Actions, With No Changes

    This paragraph restates the requirements of paragraph (l) of AD 
2011-23-05, Amendment 39-16856 (76 FR 67343, November 1, 2011), with 
no changes. Actions done in accordance with Boeing Alert Service 
Bulletin 737-53A1279, dated December 18, 2007, before November 16, 
2011 (the effective date of AD 2011-23-05), are acceptable for 
compliance with the corresponding actions required by paragraphs 
(g), (h), (i), and (j) of this AD.

(m) New Requirement of This AD: Inspections of Frames and Frame 
Reinforcements Between S-19 and S-22 for Certain Airplanes on Which 
Certain Inspections Have Not Been Accomplished

    For airplanes identified as Groups 1 through 6, Configuration 3, 
in Boeing Alert Service Bulletin 737-53A1279, Revision 2, dated 
April 21, 2015, with 30,000 total flight cycles or fewer as of the 
effective date of this AD, on which any inspections specified in 
Boeing Alert Service Bulletin 737-53A1279, Revision 1, dated 
September 2, 2011, have not been accomplished: Except as required by 
paragraphs (t)(1) and (t)(2) of this AD, at

[[Page 74051]]

the applicable time specified in table 1 of paragraph 1.E., 
``Compliance,'' of Boeing Alert Service Bulletin 737-53A1279, 
Revision 2, dated April 21, 2015, or within 4,500 flight cycles 
after the effective date of this AD, whichever occurs later, do 
inspections for cracking at certain locations in the frames and 
frame reinforcements in accordance with ``Part 2--Initial Detail and 
HFEC Inspection'' of the Accomplishment Instructions of Boeing Alert 
Service Bulletin 737-53A1279, Revision 2, dated April 21, 2015. 
Repeat the inspections for cracking at certain locations in the 
frames and frame reinforcements as specified in ``Part 4--Repeat 
Detail and HFEC Inspections'' of the Accomplishment Instructions of 
Boeing Alert Service Bulletin 737-53A1279, Revision 2, dated April 
21, 2015, thereafter at the applicable interval specified in 
paragraph 1.E., ``Compliance,'' of Boeing Alert Service Bulletin 
737-53A1279, Revision 2, dated April 21, 2015; or, before further 
flight after accomplishing an inspection and no cracking was found, 
do ``Part 5--Preventative Modification'' as specified in the 
Accomplishment Instructions of Boeing Alert Service Bulletin 737-
53A1279, Revision 2, dated April 21, 2015. Accomplishment of the 
preventive modification specified in this paragraph terminates the 
repetitive inspections required by this paragraph for the modified 
area only. Do all actions specified in this paragraph in accordance 
with Accomplishment Instructions of Boeing Alert Service Bulletin 
737-53A1279, Revision 2, dated April 21, 2015.

(n) New Requirement of This AD: Inspections of Frames and Frame 
Reinforcements Between S-19 and S-22 for Groups 1-6, Configuration 3, 
Airplanes

    For airplanes identified as Groups 1 through 6, Configuration 3, 
in Boeing Alert Service Bulletin 737-53A1279, Revision 2, dated 
April 21, 2015, with more than 30,000 total flight cycles as of the 
effective date of this AD, or that have been inspected as specified 
in Boeing Alert Service Bulletin 737-53A1279, Revision 1, dated 
September 2, 2011: Except as required by paragraphs (t)(1) and 
(t)(2) of this AD, at the applicable time specified in table 1 of 
paragraph 1.E., ``Compliance,'' of Boeing Alert Service Bulletin 
737-53A1279, Revision 2, dated April 21, 2015, do inspections for 
cracking at certain locations of the frames and frame reinforcements 
in accordance with ``Part 4--Repeat Detail and HFEC Inspections'' of 
the Accomplishment Instructions of Boeing Alert Service Bulletin 
737-53A1279, Revision 2, dated April 21, 2015. Repeat the 
inspections thereafter at the applicable interval specified in 
paragraph 1.E., ``Compliance,'' of Boeing Alert Service Bulletin 
737-53A1279, Revision 2, dated April 21, 2015; or, before further 
flight after accomplishing an inspection and no cracking was found, 
do ``Part 5--Preventative Modification'' as specified in the 
Accomplishment Instructions of Boeing Alert Service Bulletin 737-
53A1279, Revision 2, dated April 21, 2015. Accomplishment of the 
preventive modification specified in this paragraph terminates the 
repetitive inspections required by this paragraph for the modified 
area only.

(o) New Requirement of This AD: Repairs

    If any crack is found during any inspection required by 
paragraph (m) or (n) of this AD: Before further flight, repair, in 
accordance with ``Part 3--Repair'' of the Accomplishment 
Instructions of Boeing Alert Service Bulletin 737-53A1279, Revision 
2, dated April 21, 2015, except where Boeing Alert Service Bulletin 
737-53A1279, Revision 2, dated April 21, 2015, specifies to contact 
Boeing for damage removal and repair instructions, repair before 
further flight using a method approved in accordance with the 
procedures specified in paragraph (u) of this AD. Accomplishing a 
repair terminates the inspections required by paragraphs (m) and (n) 
of this AD in the repaired area only. Accomplishment of a repair 
terminates the modification required by paragraph (p) of this AD at 
the repaired location only.

(p) New Requirement of This AD: Preventative Modification of the Frames 
Between S-19 and S-22

    For airplanes identified as Groups 1 through 6, Configuration 3, 
in Boeing Alert Service Bulletin 737-53A1279, Revision 2, dated 
April 21, 2015: Except as required by paragraphs (t)(1) and (t)(2) 
of this AD, at the applicable time specified in table 2 of paragraph 
1.E., ``Compliance,'' of Boeing Alert Service Bulletin 737-53A1279, 
Revision 2, dated April 21, 2015, do the preventive modification of 
the frames between S-19 and S-22, in accordance with ``Part 5--
Preventative Modification'' of the Accomplishment Instructions of 
Boeing Alert Service Bulletin 737-53A1279, Revision 2, dated April 
21, 2015. Accomplish of the modification required by this paragraph 
terminates the requirements of paragraphs (g), (h), (m), and (n) of 
this AD for the modified location only.

(q) New Requirement of This AD: Inspections of Preventive Modification 
for Groups 1-3, Configuration 1, Airplanes

    For airplanes identified as Groups 1 through 3, Configuration 1, 
in Boeing Alert Service Bulletin 737-53A1279, Revision 2, dated 
April 21, 2015: Except as required by paragraph (t)(1) of this AD, 
at the applicable time specified in table 3 of paragraph 1.E., 
``Compliance,'' of Boeing Alert Service Bulletin 737-53A1279, 
Revision 2, dated April 21, 2015, do HFEC, LFEC, and detailed 
inspections for cracking in accordance with ``Part 7--INSPECTION OF 
PREVENTATIVE MODIFICATION'' of the Accomplishment Instructions of 
Boeing Alert Service Bulletin 737-53A1279, Revision 2, dated April 
21, 2015. Repeat the inspections thereafter at the applicable 
interval specified in paragraph 1.E., ``Compliance,'' of Boeing 
Alert Service Bulletin 737-53A1279, Revision 2, dated April 21, 
2015. If any cracking is found during any inspection required by 
this paragraph, before further flight, repair using a method 
approved in accordance with the procedures specified in paragraph 
(u) of this AD.

(r) New Requirement of This AD: Inspections of Preventive Modification 
for Groups 1-6, Configuration 2

    For airplanes identified as Groups 1 through 6, Configuration 2, 
in Boeing Alert Service Bulletin 737-53A1279, Revision 2, dated 
April 21, 2015: Except as required by paragraph (t)(1)of this AD, at 
the applicable time specified in table 4 or table 6 of paragraph 
1.E., ``Compliance,'' of Boeing Alert Service Bulletin 737-53A1279, 
Revision 2, dated April 21, 2015, do HFEC, LFEC, and detailed 
inspections for cracking in accordance with ``Part 8--INSPECTION OF 
PREVENTATIVE MODIFICATION'' of the Accomplishment Instructions of 
Boeing Alert Service Bulletin 737-53A1279, Revision 2, dated April 
21, 2015. Repeat the inspections thereafter at the applicable 
interval specified in table 4 or table 6 of paragraph 1.E., 
``Compliance,'' of Boeing Alert Service Bulletin 737-53A1279, 
Revision 2, dated April 21, 2015. If any cracking is found during 
any inspection required by this paragraph, before further flight, 
repair using a method approved in accordance with the procedures 
specified in paragraph (u) of this AD.

(s) New Requirement of This AD: Inspections of Preventive Modification 
for Group 4-6, Configuration 1, Airplanes

    For airplanes identified as Group 4 through 6, Configuration 1, 
in Boeing Alert Service Bulletin 737-53A1279, Revision 2, dated 
April 21, 2015: At the applicable time specified in table 5 of 
paragraph 1.E., ``Compliance,'' of Boeing Alert Service Bulletin 
737-53A1279, Revision 2, dated April 21, 2015, except as required by 
paragraph (t)(1) of this AD: Do HFEC, LFEC and detailed inspections 
for cracking in accordance with ``Part 7--INSPECTION OF PREVENTATIVE 
MODIFICATION'' of the Accomplishment Instructions of Boeing Alert 
Service Bulletin 737-53A1279, Revision 2, dated April 21, 2015. 
Repeat the inspections thereafter at the applicable time specified 
in paragraph 1.E., ``Compliance,'' of Boeing Alert Service Bulletin 
737-53A1279, Revision 2, dated April 21, 2015. If any cracking is 
found during any inspection required by this paragraph, before 
further flight, repair using a method approved in accordance with 
the procedures specified in paragraph (u) of this AD.

(t) New Requirement of This AD: Exceptions to Service Bulletin 
Specifications

    (1) Where paragraph 1.E., ``Compliance,'' of Boeing Alert 
Service Bulletin 737-53A1279, Revision 2, dated April 21, 2015, 
refers to a compliance time ``after the Revision 2 date of this 
service bulletin,'' this AD requires compliance within the specified 
compliance time after the effective date of this AD.
    (2) The ``Condition'' column in table 1 and table 2 of paragraph 
1.E., ``Compliance,'' of Boeing Alert Service Bulletin 737-53A1279, 
Revision 2, dated April 21, 2015, refers to total flight cycles ``at 
the Revision 2 date of this service bulletin.'' However, this AD 
applies to the airplanes with the specified total flight cycles as 
of the effective date of this AD.

[[Page 74052]]

(u) 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 (v)(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 for AD 2009-02-06, Amendment 39-15796 (74 FR 
10469, March 11, 2009); AD 2009-02-06 R1, Amendment 39-16015 (74 FR 
45979, September 6, 2009); and AD 2011-23-05, Amendment 39-16856 (76 
FR 67343, November 1, 2011); are approved as AMOCs for the 
corresponding provisions of this AD.

(v) Related Information

    (1) For more information about this AD, contact Wayne Lockett, 
Aerospace Engineer, Airframe Branch, ANM-120S, Seattle Aircraft 
Certification Office (ACO), FAA, 1601 Lind Avenue SW., Renton, 
Washington 98057-3356; phone: 425-917-6447; 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, 1601 Lind Avenue SW., Renton, Washington. 
For information on the availability of this material at the FAA, 
call 425-227-1221.

    Issued in Renton, Washington, on November 17, 2015.
Jeffrey E. Duven,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.

[FR Doc. 2015-30008 Filed 11-25-15; 8:45 am]
 BILLING CODE 4910-13-P