[Federal Register Volume 78, Number 1 (Wednesday, January 2, 2013)]
[Rules and Regulations]
[Pages 9-15]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2012-30924]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2011-1419; Directorate Identifier 2010-NM-281-AD; 
Amendment 39-17297; AD 2012-26-02]
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 an existing airworthiness directive (AD) 
for certain The Boeing Company Model 737-300, -400, and -500 series 
airplanes. That AD currently requires repetitive inspections for 
cracking of the crown area of the fuselage skin, and corrective actions 
if necessary. This new AD adds repetitive inspections for cracking 
using different inspection methods and inspecting additional areas, and 
corrective actions if necessary. This new AD also requires additional 
repairs to previously repaired areas and repetitive inspections for 
loose fasteners and replacement if necessary in certain previously 
repaired areas. This AD also reduces certain compliance times and 
extends certain other compliance times. This AD was prompted by 
additional reports of

[[Page 10]]

cracking at the horizontal chem-mill steps away from the lap joints 
over the entire crown area, and vertical chem-mill cracks adjacent to 
the butt joints. We are issuing this AD to detect and correct fatigue 
cracking of the fuselage skin, which could cause the fuselage skin to 
fracture and fail, and result in rapid decompression of the airplane.

DATES: This AD is effective February 6, 2013.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in the AD as of February 6, 
2013.
    The Director of the Federal Register approved the incorporation by 
reference of a certain other publication listed in this AD as of August 
1, 2005 (70 FR 36821, June 27, 2005).

ADDRESSES: For service information identified in this AD, contact 
Boeing Commercial Airplanes, Attention: Data & Services Management, 
P.O. Box 3707, MC 2H-65, Seattle, Washington 98124-2207; telephone 206-
544-5000, extension 1; fax 206-766-5680; Internet https://www.myboeingfleet.com. You may review copies of the 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.

Examining the AD Docket

    You may examine the AD docket on the Internet at http://www.regulations.gov; 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 Document 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: Wayne Lockett, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue SW., Renton, Washington 98057-3356; phone: (425) 917-
6447; fax: (425) 917-6590; email: [email protected].

SUPPLEMENTARY INFORMATION:

Discussion

    We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR 
part 39 to supersede AD 2005-13-27, Amendment 39-14164 (70 FR 36821, 
June 27, 2005). That AD applies to the specified products. The NPRM 
published in the Federal Register on January 19, 2012 (77 FR 2669). 
That NPRM proposed to continue to require repetitive inspections for 
cracking of the crown area of the fuselage skin, and corrective actions 
if necessary. That NPRM also proposed to add repetitive inspections for 
cracking using different inspection methods and would inspect 
additional areas, and corrective actions if necessary. That NPRM also 
proposed to require additional repairs to previously repaired areas and 
repetitive inspections for loose fasteners and replacement if necessary 
in certain previously repaired areas. That NPRM also proposed to reduce 
certain compliance times and extend certain other compliance times.

Comments

    We gave the public the opportunity to participate in developing 
this AD. The following presents the comments received on the proposal 
(77 FR 2669, January 19, 2012) and the FAA's response to each comment.

Concurrence With NPRM (77 FR 2669, January 19, 2012)

    The National Transportation Safety Board stated that it fully 
supports the NPRM (77 FR 2669, January 19, 2012).

Request To Correct References to Repair Instructions

    Boeing asked that we revise the NPRM (77 FR 2669, January 19, 2012) 
to correct references to certain repair instructions. Boeing stated 
that paragraph (n)(2)(iii) of the NPRM specifies converting the time-
limited repair into a permanent repair by doing the permanent repair 
specified in paragraph (n)(1) of the NPRM. Boeing noted that paragraph 
(n)(1) of the NPRM specifies installing a permanent repair in 
accordance with ``Part 2'' of the Accomplishment Instructions of Boeing 
Alert Service Bulletin 737-53A1234, Revision 2, dated November 24, 
2010; however, Part 2 does not give instructions for changing the time-
limited repair to a permanent repair. Boeing stated that paragraph 
(t)(2) of the NPRM also incorrectly refers to converting the time-
limited repair into a permanent repair by doing the permanent repair 
specified in paragraph (n)(1) of the NPRM.
    Boeing stated that the correct instructions for converting the 
time-limited repair to a permanent repair are specified in Part 4 of 
the Accomplishment Instructions of Boeing Alert Service Bulletin 737-
53A1234, Revision 2, dated November 24, 2010, and added that paragraphs 
(n)(2)(iii) and (t)(2) of the NPRM (77 FR 2669, January 19, 2012) 
should specify doing the permanent repair in accordance with Part 4 of 
the Accomplishment Instructions of that service information.
    We agree that the reference to paragraph (n)(1) of this AD for 
doing the permanent repair identified in paragraphs (n)(2)(iii) and 
(t)(2) of this AD is incorrect. We have changed paragraph (n)(2)(iii) 
of this AD to specify doing the permanent repair in accordance with 
Part 4 of the Accomplishment Instructions of Boeing Alert Service 
Bulletin 737-53A1234, Revision 2, dated November 24, 2010. In addition, 
we have changed paragraph (t)(2) of this AD to refer to paragraph 
(t)(3) of this AD for the permanent repair. Paragraph (t)(3) of this AD 
specifies doing the permanent repair in accordance with paragraph 
3.B.4. (i.e., Part 4) of the service information.

Request To Remove Certain Terminating Action

    Boeing asked that we delete the last sentence in paragraph (t)(1) 
of the NPRM (77 FR 2669, January 19, 2012), which specified that 
installation of internal tear strap doublers would terminate the 
inspections required by paragraph (m) of the NPRM. Boeing stated that 
this sentence is not necessary because there are no inspection 
requirements in paragraph (m) of the NPRM for the areas covered by 
permanent repairs installed without tear strap doublers.
    We agree with the commenter for the reason provided. We have 
deleted the referenced sentence in paragraph (t)(1) of this AD.

Request To Add Certain Terminating Action Language

    Southwest Airlines (SWA) asked that we add language to paragraphs 
(n) and (s) of the NPRM (77 FR 2669, January 19, 2012), specifying that 
repairs installed in accordance with paragraphs (n) and (s) of the NPRM 
terminate the inspections required by paragraphs (m), (o), (p), and (q) 
of the NPRM.
    We partially agree with the commenter's request. The repetitive 
inspections may be terminated after a time-limited or permanent repair 
has been installed, for the repaired area only. We note that paragraph 
(n) of this AD specifies that doing a permanent repair terminates the 
inspections specified in paragraph (m) of this AD for the repaired area 
only. We also note that paragraph (n) of this AD does not terminate 
paragraphs (o), (p), and (q) of this AD. Accomplishing paragraph (s) of 
this AD terminates the inspections

[[Page 11]]

required by paragraphs (o), (p), and (q) of this AD. We have changed 
paragraph (s) of this AD accordingly.

Request To Include Additional Service Information

    SWA asked that we include the internal inspection procedure 
specified in Boeing 737 Nondestructive Test (NDT) Manual, Part 6, 
Chapter 53-30-20, as an acceptable method for accomplishing the 
inspections in areas covered by non-terminating repairs as required by 
paragraphs (m), (o), (p), and (q) of the NPRM (77 FR 2669, January 19, 
2012). SWA stated that the inspection procedure in the NDT manual has 
been previously approved as an alternative inspection method for 
paragraph (s) of AD 2005-13-27, Amendment 39-14164 (70 FR 36821, June 
27, 2005), in areas covered by an existing repair that do not meet the 
terminating repair specified in the compliance tables in Boeing Alert 
Service Bulletin 737-53A1234, Revision 2, dated November 24, 2010.
    We disagree with the commenter's request. Operators may submit a 
request for approval of an alternative method of compliance (AMOC) to 
use the inspection procedure specified in the NDT manual for 
accomplishing the inspections in areas covered by non-terminating 
repairs, as specified in paragraph (x) of this AD. We have not changed 
this AD in this regard.

Request To Change Compliance Time

    SWA asked that we change the compliance time for the inspections 
proposed by paragraphs (g), (m), (o), (p), and (q) of the NPRM (77 FR 
2669, January 19, 2012) from ``total flight cycles'' to ``flight cycles 
since panel replacement'' for airplanes on which fuselage crown skin 
panels that were replaced in accordance with Boeing Service Bulletin 
737-53-1306, dated September 22, 2010; Revision 1, dated March 17, 
2011; or Revision 2, dated October 25, 2011. SWA stated that this 
modification replaces crown skin panels with new skin panels, and the 
new skin panels should have a threshold ``from panel replacement,'' and 
not ``total airplane cycles.'' SWA added that accomplishing Boeing 
Service Bulletin 737-53-1306, original issue, Revision 1, or Revision 2 
has been approved previously as an AMOC to certain requirements in 
multiple ADs; including AD 2005-13-27, Amendment 39-14164 (70 FR 36821, 
June 27, 2005), which is being superseded by the NPRM. SWA stated that 
the AMOC provides approval for changes in compliance time from total 
flight cycles to cycles since panel replacement.
    We do not agree with the commenter's request to change paragraphs 
(g), (m), (o), (p), and (q) of this AD. The existing AMOC discussed by 
the commenter is approved for the restated requirements of this AD, 
including paragraph (g) of this AD. Due to the extent of the 
replacement specified in Boeing Service Bulletin 737-53-1306, dated 
September 22, 2010; Revision 1, dated March 17, 2011; or Revision 2, 
dated October 25, 2011, and the number of ADs that affect that 
replacement, we have determined that clarification of the AMOCs for all 
these ADs should be provided in a separate AMOC letter. This will 
ensure that multiple parties (e.g., Flight Standards, Maintenance 
Repair and Overhaul facilities (MROs), and operators) have access to 
the approval information for the replacement in one document. We have 
made no change to this AD in this regard.

Request for Alternate Option for Inspections

    SWA asked that we revise the NPRM (77 FR 2669, January 19, 2012) to 
allow the inspections in paragraph (w) of the NPRM as an alternate 
option for the permanent repairs required by paragraph (t) of the NPRM 
for airplanes on which internal tear strap doublers were not installed. 
SWA stated that permanent repairs installed in accordance with Boeing 
Special Attention Service Bulletin 737-53-1234, dated June 13, 2001; or 
Revision 1, dated March 31, 2005; have been evaluated and determined to 
meet the damage tolerance requirements of part 26 of the Federal 
Aviation Regulations (14 CFR Part 26), as indicated in Figure 41 of 
Boeing Alert Service Bulletin 737-53A1234, Revision 2, dated November 
24, 2010. SWA added that accomplishing the post-repair inspections in 
accordance with Figure 41, at the time specified in Table 7 of 
paragraph 1.E., ``Compliance,'' of Boeing Alert Service Bulletin 737-
53A1234, Revision 2, dated November 24, 2010, should be considered an 
alternate option to the requirements in paragraph (t) of the NPRM.
    We do not agree with the commenter's request. The 60,000-flight-
cycle threshold for the post-repair inspection addresses the critical 
outer fastener row installed with the repair doubler, and does not 
address the area of the tear strap doubler installed in accordance with 
paragraph (t)(1) of this AD. We have made no change to this AD in this 
regard.

Request To Provide Clarification

    SWA asked that we provide clarification whether the notes in 
paragraph 3.B. of the Accomplishment Instructions of Boeing Alert 
Service Bulletin 737-53A1234, Revision 2, dated November 24, 2010, are 
applicable to paragraphs (m), (o), (p), and (q) of the NPRM (77 FR 
2669, January 19, 2012).
    We agree to provide clarification. The notes specified in paragraph 
3.A., ``General Information,'' and paragraph 3.B., ``Work 
Instructions,'' of the Accomplishment Instructions of Boeing Alert 
Service Bulletin 737-53A1234, Revision 2, dated November 24, 2010, 
apply to all the sub-paragraphs of the Accomplishment Instructions, 
including the actions that correspond to the requirements of paragraphs 
(m), (o), (p), and (q) of this AD. We have made no change to this AD in 
this regard.

Explanation of Change to This AD

    We have revised the heading for and the wording in paragraph (l) of 
this AD; this change has not changed the intent of that paragraph.

Conclusion

    We reviewed the relevant data, considered the comments received, 
and determined that air safety and the public interest require adopting 
the 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 (77 FR 2669, January 19, 2012) for correcting the unsafe 
condition; and
     Do not add any additional burden upon the public than was 
already proposed in the NPRM (77 FR 2669, January 19, 2012).
    We also determined that these changes will not increase the 
economic burden on any operator or increase the scope of the AD.

Costs of Compliance

    We estimate that this AD affects 109 airplanes of U.S. registry.
    We estimate the following costs to comply with this AD:

[[Page 12]]



                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
               Action                      Labor cost          Cost per product       Cost on U.S.  operators
----------------------------------------------------------------------------------------------------------------
Inspection (retained actions from    94 work-hours x $85    $7,990 per inspection  $870,910
 AD 2005-13-27, Amendment             per hour = $7,990.     cycle.
 39[dash]14164 (70 FR 36821, June
 27, 2005)).
New NDI (non-destructive             Up to 390 work-hours   Up to $33,150 per      Up to $3,613,350.
 inspection) Inspections (medium      x $85 per hour =       inspection cycle.
 frequency eddy current, magneto      $33,150.
 optical imaging, C-scan, or
 ultrasonic phased array).
Install internal tear strap          Up to 30               Up to $2,550.........  Up to $277,950.
 doublers (for airplanes on which     work[dash]hours x
 permanent repair was already done).  $85 per hour =
                                      $2,550.
Inspection for loose fasteners (for  1 work-hour x $85 per  $85..................  $9,265.
 airplanes on which temporary         hour = $85.
 repair was already done)[sup1].
Install permanent repair (for        Up to 48               Up to $4,080.........  Up to $444,720.
 airplanes on which temporary         work[dash]hours x
 repair was already done)[sup1].      $85 per hour =
                                      $4,080.
Inspection adjacent to lap joint     3 work-hours x $85     $255.................  $27,795.
 repair[sup1].                        per hour = $255.
----------------------------------------------------------------------------------------------------------------
\1\ The cost for this action is for one typical repair only.

    We estimate the following costs to do any necessary repairs that 
would be required based on the results of the inspection. 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
----------------------------------------------------------------------------------------------------------------
Repair \1\..........................  209 work-hours x $85     None...................  $17,765.
                                       per hour = $17,765.
----------------------------------------------------------------------------------------------------------------
\1\ Repair cost estimate is for one typical repair only.

Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to 
issue rules on aviation safety. Subtitle I, Section 106, describes the 
authority of the FAA Administrator. Subtitle VII, Aviation Programs, 
describes in more detail the scope of the Agency's authority.
    We are issuing this rulemaking under the authority described in 
Subtitle VII, Part A, Subpart III, Section 44701, ``General 
requirements.'' Under that section, Congress charges the FAA with 
promoting safe flight of civil aircraft in air commerce by prescribing 
regulations for practices, methods, and procedures the Administrator 
finds necessary for safety in air commerce. This regulation is within 
the scope of that authority because it addresses an unsafe condition 
that is likely to exist or develop on products identified in this 
rulemaking action.

Regulatory Findings

    We have determined that this AD will not have federalism 
implications under Executive Order 13132. This AD will not have a 
substantial direct effect on the States, on the relationship between 
the national government and the States, or on the distribution of power 
and responsibilities among the various levels of government.
    For the reasons discussed above, I certify that this AD:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866,
    (2) Is not a ``significant rule'' under DOT Regulatory Policies and 
Procedures (44 FR 11034, February 26, 1979),
    (3) Will not affect intrastate aviation in Alaska, and
    (4) Will not have a significant economic impact, positive or 
negative, on a substantial number of small entities under the criteria 
of the Regulatory Flexibility Act.

List of Subjects in 14 CFR Part 39

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

Adoption of the Amendment

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

PART 39--AIRWORTHINESS DIRECTIVES

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

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

Sec.  39.13  [Amended]

0
2. The FAA amends Sec.  39.13 by removing airworthiness directive (AD) 
2005-13-27, Amendment 39-14164 (70 FR 36821, June 27, 2005), and adding 
the following new AD:

2012-26-02 The Boeing Company: Amendment 39-17297; Docket No. FAA-
2011-1419; Directorate Identifier 2010-NM-281-AD.

(a) Effective Date

    This airworthiness directive (AD) is effective February 6, 2013.

(b) Affected ADs

    This AD supersedes AD 2005-13-27, Amendment 39-14164 (70 FR 
36821, June 27, 2005).

(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 737-53A1234, Revision 2, dated 
November 24, 2010.

(d) Subject

    Joint Aircraft System Component (JASC)/Air Transport Association 
(ATA) of America Code 53, Fuselage.

(e) Unsafe Condition

    This AD was prompted by reports of cracking at the horizontal 
chem-mill steps away from the lap joints over the entire crown area, 
and vertical chem-mill cracks adjacent to the butt joints. We are 
issuing this AD to detect and correct fatigue cracking of the 
fuselage skin, which could cause the fuselage skin to fracture and 
fail, and result in rapid decompression of the airplane.

(f) Compliance

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

[[Page 13]]

(g) Retained Initial Inspections

    This paragraph restates the requirements of paragraph (g) of AD 
2005-13-27, Amendment 39-14164 (70 FR 36821, June 27, 2005). At the 
later of the times specified in paragraphs (g)(1) and (g)(2) of this 
AD, perform detailed and eddy current inspections for cracking of 
the crown area of the fuselage skin in accordance with Part 1, 
including the ``Note,'' of the Work Instructions of Boeing Special 
Attention Service Bulletin 737-53-1234, Revision 1, dated March 31, 
2005, except as provided by paragraph (j) of this AD. Doing the 
inspections required by paragraph (m) of this AD terminates the 
inspections required by this paragraph for the corresponding 
inspection areas.
    (1) Before the accumulation of the applicable total flight 
cycles specified in the ``Threshold'' column of Table 1 of Figure 1 
of Boeing Special Attention Service Bulletin 737-53-1234, Revision 
1, dated March 31, 2005.
    (2) Within 4,500 flight cycles after August 1, 2005 (the 
effective date of AD 2005-13-27, Amendment 39-14164 (70 FR 36821, 
June 27, 2005).

(h) Retained Repetitive Inspections

    This paragraph restates the requirements of paragraph (h) of AD 
2005-13-27, Amendment 39-14164 (70 FR 36821, June 27, 2005). Repeat 
either the detailed or eddy current inspections specified in 
paragraph (g) of this AD at the applicable intervals specified in 
paragraph (h)(1) or (h)(2) of this AD until paragraph (i)(1) or 
(i)(2) of this AD has been done, as applicable. Doing the inspection 
required by paragraph (m) of this AD terminates the inspections 
required by this paragraph for the corresponding inspection area.
    (1) Repeat the detailed inspections thereafter at intervals not 
to exceed 1,200 flight cycles.
    (2) Repeat the eddy current inspections thereafter at intervals 
not to exceed 3,000 flight cycles.

(i) Retained Permanent or Time-Limited Repair for Cracking Found During 
Inspections

    This paragraph restates the requirements of paragraph (i) of AD 
2005-13-27, Amendment 39-14164 (70 FR 36821, June 27, 2005). If any 
cracking is found during any inspection required by paragraph (g) or 
(h) of this AD, do the actions specified in paragraph (i)(1) or 
(i)(2) of this AD, in accordance with Boeing Special Attention 
Service Bulletin 737-53-1234, Revision 1, dated March 31, 2005, 
except as provided by paragraphs (j) and (k) of this AD.
    (1) Before further flight, do a permanent repair (including 
related investigative actions and applicable corrective actions) in 
accordance with Part 2 of the Work Instructions of Boeing Special 
Attention Service Bulletin 737-53-1234, Revision 1, dated March 31, 
2005. Doing a permanent repair ends the repetitive inspections 
required by paragraph (h) of this AD for the repaired area only.
    (2) Do the actions specified in paragraphs (i)(2)(i) and 
(i)(2)(ii) of this AD at the time specified in the applicable 
paragraph. Doing a time-limited repair ends the repetitive 
inspections required by paragraph (h) of this AD for the repaired 
area only.
    (i) Before further flight, do a time-limited repair (including 
related investigative actions and applicable corrective actions) in 
accordance with Part 3 of the Work Instructions of Boeing Special 
Attention Service Bulletin 737-53-1234, Revision 1, dated March 31, 
2005.
    (ii) At the times specified in Figure 8 of Boeing Special 
Attention Service Bulletin 737-53-1234, Revision 1, dated March 31, 
2005, do the related investigative and corrective actions in 
accordance with Part 3 of the Work Instructions of Boeing Special 
Attention Service Bulletin 737-53-1234, Revision 1, dated March 31, 
2005.

(j) Retained Provision for Repair per FAA

    This paragraph restates the requirements of paragraph (j) of AD 
2005-13-27, Amendment 39-14164 (70 FR 36821, June 27, 2005). Where 
Boeing Special Attention Service Bulletin 737-53-1234, Revision 1, 
dated March 31, 2005, specifies to contact Boeing for appropriate 
action: Before further flight, repair according to a method approved 
by the Manager, Seattle Aircraft Certification Office (ACO), FAA; or 
according to data meeting the certification basis of the airplane 
approved by an Authorized Representative for the Boeing Delegation 
Option Authorization Organization who has been authorized by the 
Manager, Seattle ACO, to make those findings; or using a method 
approved in accordance with the procedures specified in paragraph 
(x) of this AD. For a repair method to be approved, the approval 
must specifically reference this AD.

(k) Retained Provision, Reporting Not Required

    This paragraph restates the provisions of paragraph (k) of AD 
2005-13-27, Amendment 39-14164 (70 FR 36821, June 27, 2005). 
Although Boeing Special Attention Service Bulletin 737-53-1234, 
Revision 1, dated March 31, 2005, specifies reporting certain 
information to Boeing, this AD does not require that action.

(l) Retained Credit for Previous Actions

    This paragraph restates the requirements of paragraph (l) of AD 
2005-13-27, Amendment 39-14164 (70 FR 36821, June 27, 2005). Actions 
done before August 1, 2005, in accordance with Boeing Special 
Attention Service Bulletin 737-53-1234, dated June 13, 2002 (which 
is not incorporated by reference in this AD), are acceptable for 
compliance with the corresponding actions required by paragraphs 
(g), (h), and (i) of this AD.

(m) New Fuselage Skin Inspections at Chem-Mill Steps Common to Lap 
Joints

    Except as provided by paragraph (v)(1) of this AD, at the 
applicable time specified in Tables 1 and 2 of paragraph 1.E, 
``Compliance,'' of Boeing Alert Service Bulletin 737-53A1234, 
Revision 2, dated November 24, 2010: Do a non-destructive inspection 
(NDI) (medium frequency eddy current, magneto optical imaging, C-
scan, or ultrasonic phased array) for horizontal chem-mill cracking 
above the S-4 and S-10 lap joints, in accordance with paragraph 
3.B.1.a. of the Accomplishment Instructions of Boeing Alert Service 
Bulletin 737-53A1234, Revision 2, dated November 24, 2010, except as 
provided by paragraph (r) of this AD. Repeat the applicable 
inspections thereafter at intervals not to exceed those specified in 
paragraph 1.E., ``Compliance,'' of Boeing Alert Service Bulletin 
737-53A1234, Revision 2, dated November 24, 2010. Accomplishment of 
the inspections required by this paragraph terminates the 
requirements of paragraphs (g) and (h) of this AD for the 
corresponding inspection areas.

    Note 1 to paragraph (m) of this AD:
     Option 1 of Boeing Alert Service Bulletin 737-53A1234, Revision 
2, dated November 24, 2010, specifies doing one of the following 
NDI: Medium frequency eddy current inspection, magneto optical 
imaging inspection, or C-scan inspection. Option 2 specifies doing 
one NDI--an external ultrasonic phased array inspection. These 
options have different compliance times after the initial 
inspection.

(n) New Permanent or Time-Limited Repair for Cracking Found During 
Inspections Required by Paragraph (m) of This AD

    If any cracking is found during any inspection required by 
paragraph (m) of this AD, do the actions specified in paragraph 
(n)(1) or (n)(2) of this AD.
    (1) Before further flight, do a permanent repair, including 
related investigative actions and applicable corrective actions, in 
accordance with Part 2 of the Accomplishment Instructions of Boeing 
Alert Service Bulletin 737-53A1234, Revision 2, dated November 24, 
2010, except as provided by paragraph (v)(2) of this AD. Doing a 
permanent repair ends the repetitive inspections required by 
paragraph (m) of this AD for the repaired area only.
    (2) Do the actions specified in paragraphs (n)(2)(i), 
(n)(2)(ii), and (n)(2)(iii) of this AD at the time specified in the 
applicable paragraph. Doing a time-limited repair ends the 
repetitive inspections required by paragraph (m) of this AD for the 
repaired area only.
    (i) Before further flight, do a time-limited repair, including 
related investigative actions and applicable corrective actions, in 
accordance with Part 4 of the Accomplishment Instructions of Boeing 
Alert Service Bulletin 737-53A1234, Revision 2, dated November 24, 
2010, except as provided by paragraph (v)(2) of this AD.
    (ii) Within 3,000 flight cycles after the time-limited repair 
was installed as specified in paragraph (n)(2)(i) of this AD, or 
within 500 flight cycles after the effective date of this AD, 
whichever occurs later, do a detailed inspection for loose 
fasteners, in accordance with Part 4 of the Accomplishment 
Instructions of Boeing Alert Service Bulletin 737-53A1234, Revision 
2, dated November 24, 2010. Repeat the inspection thereafter at 
intervals not to exceed 3,000 flight cycles until the permanent 
repair required by paragraph (n)(2)(iii) of this AD is done. If any 
loose fasteners are found, before further flight, replace the 
fasteners with new fasteners of the same type and size, as specified 
in Figures 6, 35, and 36 of Boeing

[[Page 14]]

Alert Service Bulletin 737-53A1234, Revision 2, dated November 24, 
2010.
    (iii) Within 6,000 flight cycles after the time-limited repair 
was installed, as specified in paragraph (n)(2)(i) of this AD, do 
the permanent repair, in accordance with Part 4 of the 
Accomplishment Instructions of Boeing Alert Service Bulletin 737-
53A1234, Revision 2, dated November 24, 2010, except as provided by 
paragraph (v)(2) of this AD.

(o) New Fuselage Skin Inspections at Chem-Mill Steps Common to Shear 
Wrinkle Areas

    Except as provided by paragraph (v)(1) of this AD, at the 
applicable time specified in Table 3 of paragraph 1.E, 
``Compliance,'' of Boeing Alert Service Bulletin 737-53A1234, 
Revision 2, dated November 24, 2010: Do an NDI (medium frequency 
eddy current, magneto optical imaging, C-scan, or ultrasonic phased 
array) for horizontal chem-mill cracking in the shear wrinkle areas, 
in accordance with paragraph 3.B.1.b of the Accomplishment 
Instructions of Boeing Alert Service Bulletin 737-53A1234, Revision 
2, dated November 24, 2010. Repeat the applicable inspections 
thereafter at intervals not to exceed those specified in paragraph 
1.E., ``Compliance,'' of Boeing Alert Service Bulletin 737-53A1234, 
Revision 2, dated November 24, 2010.

(p) New Fuselage Skin Inspections at Specified Vertical Chem-Mill Step 
Locations

    Except as provided by paragraph (v)(1) of this AD, at the 
applicable time specified in Table 4 of paragraph 1.E, 
``Compliance,'' of Boeing Alert Service Bulletin 737-53A1234, 
Revision 2, dated November 24, 2010: Do an NDI (medium frequency 
eddy current, magneto optical imaging, C-scan, or ultrasonic phased 
array) for vertical chem-mill cracking at locations specified in, 
and in accordance with paragraph 3.B.1.c. of the Accomplishment 
Instructions of Boeing Alert Service Bulletin 737-53A1234, Revision 
2, dated November 24, 2010. Repeat the applicable inspections 
thereafter at intervals not to exceed those specified in paragraph 
1.E., ``Compliance,'' of Boeing Alert Service Bulletin 737-53A1234, 
Revision 2, dated November 24, 2010.

(q) New Fuselage Skin Inspections at Chem-Mill Steps in General Pocket-
to-Pocket Areas

    Except as provided by paragraph (v)(1) of this AD, at the 
applicable time specified in Tables 5 and 6 of paragraph 1.E, 
``Compliance,'' of Boeing Alert Service Bulletin 737-53A1234, 
Revision 2, dated November 24, 2010: Do an NDI (medium frequency 
eddy current, magneto optical imaging, C-scan, or ultrasonic phased 
array) for horizontal chem-mill cracking in general pocket-to-pocket 
areas at specified locations in and in accordance with paragraphs 
3.B.1.d., 3.B.1.e., and 3.B.1.f., as applicable, of the 
Accomplishment Instructions of Boeing Alert Service Bulletin 737-
53A1234, Revision 2, dated November 24, 2010. Repeat the applicable 
inspections thereafter at intervals not to exceed those specified in 
Tables 5 and 6 of paragraph 1.E., ``Compliance,'' of Boeing Alert 
Service Bulletin 737-53A1234, Revision 2, dated November 24, 2010.

(r) New Inspection Exception

    For inspections required by paragraph (m) of this AD: It is not 
necessary to inspect the chem-mill steps under an existing repair 
installed using Boeing Special Attention Service Bulletin 737-53-
1234, dated June 13, 2002 (which is not incorporated by reference in 
this AD); or Revision 1, dated March 31, 2005.

(s) New Repair of Cracking Found During Inspections Required by 
Paragraphs (o) Through (q) of This AD

    If any crack is found during any inspection required by 
paragraph (o), (p), or (q) of this AD, before further flight, repair 
the crack using a method approved in accordance with the procedures 
specified in paragraph (x) of this AD. Doing this repair ends the 
repetitive inspections required by paragraphs (o), (p), and (q) of 
this AD for the repaired area only.

(t) New Actions for Airplanes on Which Repairs Have Been Done Using 
Previous Service Information

    (1) For airplanes on which permanent repairs have been done as 
specified in Boeing Special Attention Service Bulletin 737-53-1234, 
dated June 13, 2002 (which is not incorporated by reference in this 
AD); or Revision 1, dated March 31, 2005; except airplanes on which 
internal tear strap doublers were previously installed using a 
repair plan approved using the procedures specified in paragraph (x) 
of this AD: Within 6,000 flight cycles after the effective date of 
this AD, install internal tear strap doublers, in accordance with 
paragraph 3.B.3. of the Accomplishment Instructions of Boeing Alert 
Service Bulletin 737-53A1234, Revision 2, dated November 24, 2010, 
except as provided by paragraph (v)(2) of this AD.
    (2) For airplanes on which time-limited repairs have been 
installed as specified in Boeing Special Attention Service Bulletin 
737-53-1234, dated June 13, 2002 (which is not incorporated by 
reference in this AD); or Revision 1, dated March 31, 2005; except 
airplanes on which the permanent repair has been installed before 
the effective date of this AD as specified in Boeing Special 
Attention Service Bulletin 737-53-1234, dated June 13, 2002 (which 
is not incorporated by reference in this AD); or Revision 1, dated 
March 31, 2005: Within 3,000 flight cycles after the time limited 
repair is installed, or within 500 flight cycles after the effective 
date of the AD, whichever occurs later, do a detailed inspection for 
loose fasteners, in accordance with paragraph 3.B.4. of the 
Accomplishment Instructions of Boeing Alert Service Bulletin 737-
53A1234, Revision 2, dated November 24, 2010. Repeat the inspection 
thereafter at intervals not to exceed 3,000 flight cycles until the 
permanent repair is installed in accordance with paragraph (t)(3) of 
this AD. If any loose fasteners are found, before further flight, 
replace the fasteners with new fasteners of the same type and size, 
as specified in Figures 6, 35, and 36, as applicable, of Boeing 
Alert Service Bulletin 737-53A1234, Revision 2, dated November 24, 
2010.
    (3) For airplanes on which time-limited repairs have been 
installed as specified in Boeing Special Attention Service Bulletin 
737-53-1234, dated June 13, 2002 (which is not incorporated by 
reference in this AD); or Revision 1, dated March 31, 2005; except 
airplanes on which the permanent repair has been installed before 
the effective date of this AD as specified in Boeing Special 
Attention Service Bulletin 737-53-1234, dated June 13, 2002, or 
Revision 1, dated March 31, 2005; before the effective date of this 
AD: Within 6,000 flight cycles after the time-limited repair is 
installed, or within 1,000 flight cycles after the effective date of 
this AD, whichever occurs later, make the repair permanent by 
replacing the blind fasteners in the time-limited repair with solid 
rivets, and install internal tear strap doublers, in accordance with 
paragraph 3.B.4. of the Accomplishment Instructions of Boeing Alert 
Service Bulletin 737-53A1234, Revision 2, dated November 24, 2010, 
except as provided by paragraph (v)(2) of this AD.

(u) New Action Not in Accomplishment Instructions of Service 
Information

    If any crack is found after the time-limited or permanent repair 
is installed, and Boeing Alert Service Bulletin 737-53A1234, 
Revision 2, dated November 24, 2010, specifies to contact Boeing for 
appropriate action: Before further flight, repair the crack using a 
method approved in accordance with the procedures specified in 
paragraph (x) of this AD.

(v) Exceptions to Boeing Alert Service Bulletin 737-53A1234, Revision 
2, Dated November 24, 2010

    (1) Where paragraph 1.E., ``Compliance,'' of Boeing Alert 
Service Bulletin 737-53A1234, Revision 2, dated November 24, 2010, 
specifies a compliance time relative to the ``release of Revision 2 
of this service bulletin,'' this AD requires compliance within the 
specified compliance time after the effective date of this AD.
    (2) Where Boeing Alert Service Bulletin 737-53A1234, Revision 2, 
dated November 24, 2010, specifies to contact Boeing for appropriate 
action: Before further flight, repair the cracking using a method 
approved in accordance with the procedures specified in paragraph 
(x) of this AD.
    (3) Although Boeing Alert Service Bulletin 737-53A1234, Revision 
2, dated November 24, 2010, specifies reporting certain information 
to Boeing, this AD does not require that action.

(w) Post-Repair Inspections Not Required

    The post-repair inspection specified in Table 7 of paragraph 
1.E., ``Compliance,'' of Boeing Alert Service Bulletin 737-53A1234, 
Revision 2, dated November 24, 2010, is not required by this AD.

    Note 2 to paragraph (w) of this AD:
    The damage tolerance inspections specified in Table 7 of 
paragraph 1.E., ``Compliance,'' of Boeing Alert Service Bulletin 
737-53A1234, Revision 2, dated November 24, 2010, may be used in 
support of compliance with section 121.1109(c)(2) or 129.109(c)(2) 
of the Federal Aviation Regulations (14 CFR 121.1109(c)(2) or 14 CFR 
129.109(c)(2)). The corresponding actions specified in the 
Accomplishment Instructions and Figures 40 and 41 of Boeing Alert 
Service Bulletin 737-53A1234,

[[Page 15]]

Revision 2, dated November 24, 2010, are not required in this AD.

(x) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, Seattle 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 the 
Related Information section 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 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. For a repair method to be approved, the repair must 
meet the certification basis of the airplane, and the approval must 
specifically refer to this AD.
    (4) AMOCs approved previously in accordance with AD 2005-13-27, 
Amendment 39-14164 (70 FR 36821, June 27, 2005), are approved as 
AMOCs for the corresponding requirements in this AD.

(y) Related Information

    (1) For more information about this AD, contact Wayne Lockett, 
Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft 
Certification Office, 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, Washington 98124-2207; telephone 
206-544-5000, extension 1; fax 206-766-5680; Internet https://www.myboeingfleet.com. You may review copies of the 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.

(z) 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.
    (3) The following service information was approved on February 
6, 2013.
    (i) Boeing Alert Service Bulletin 737-53A1234, Revision 2, dated 
November 24, 2010.
    (ii) Reserved.
    (4) The following service information was approved for IBR on 
August 1, 2005 (70 FR 36821, June 27, 2005).
    (i) Boeing Special Attention Service Bulletin 737-53-1234, 
Revision 1, dated March 31, 2005.
    (ii) Reserved.
    (5) For service information identified in this AD, contact 
Boeing Commercial Airplanes, Attention: Data & Services Management, 
P. O. Box 3707, MC 2H-65, Seattle, Washington 98124-2207; telephone 
206-544-5000, extension 1; fax 206-766-5680; Internet https://www.myboeingfleet.com.
    (6) You may review copies of the 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.
    (7) 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 December 12, 2012.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2012-30924 Filed 12-31-12; 8:45 am]
BILLING CODE 4910-13-P