Airworthiness Directives; The Boeing Company Airplanes, 60660-60667 [2013-24034]

Agencies

• Federal Aviation Administration
• DEPARTMENT OF TRANSPORTATION

[Federal Register Volume 78, Number 191 (Wednesday, October 2, 2013)]
[Rules and Regulations]
[Pages 60660-60667]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2013-24034]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2011-0155; Directorate Identifier 2009-NM-141-AD; 
Amendment 39-17581; AD 2013-18-08]
RIN 2120-AA64


Airworthiness Directives; The Boeing Company Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: We are superseding airworthiness directive (AD) 2004-18-06 for 
certain The Boeing Company Model 737-200, -200C, -300, -400, and -500 
series airplanes. AD 2004-18-06 required repetitive inspections to find 
fatigue cracking of certain upper and lower skin panels of the 
fuselage, and follow-on and corrective actions if necessary. AD 2004-
18-06 also included a terminating action for the repetitive inspections 
of certain modified or repaired areas only. This new AD adds new 
inspections for cracking of the fuselage skin along certain chem-milled 
lines, and corrective actions if necessary. This new AD also reduces 
certain thresholds and intervals required by AD 2004-18-06. This AD was 
prompted by new findings of vertical cracks along chem-milled steps 
adjacent to the butt joints. We are issuing this AD to detect and 
correct fatigue cracking of the skin panels, which could result in 
sudden fracture and failure of the skin panels of the fuselage, and 
consequent rapid decompression of the airplane.

DATES: This AD is effective November 6, 2013.
    The Director of the Federal Register approved the incorporation by 
reference of certain publications listed in the AD as of November 6, 
2013.
    The Director of the Federal Register approved the incorporation by 
reference of a certain other publication listed in the AD as of October 
13, 2004 (69 FR 54206, September 8, 2004).

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 https://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: wayne.lockett@faa.gov.

SUPPLEMENTARY INFORMATION:

Discussion

    We issued a supplemental notice of proposed rulemaking (SNPRM) to 
amend 14 CFR part 39 to supersede AD 2004-18-06, Amendment 39-13784 (69 
FR 54206, September 8, 2004). AD 2004-18-06 applied to the specified 
products. The SNPRM published in the

[[Page 60661]]

Federal Register on October 10, 2012 (77 FR 61550). We preceded the 
SNPRM with a notice of proposed rulemaking (NPRM) that published in the 
Federal Register on March 8, 2011 (76 FR 12619). The NPRM proposed to 
continue to require repetitive inspections to find fatigue cracking of 
certain upper and lower skin panels of the fuselage, and follow-on and 
corrective actions if necessary. The NPRM also included a terminating 
action for the repetitive inspections of certain modified or repaired 
areas only. The NPRM proposed to add new inspections for cracking of 
the fuselage skin along certain chem-milled lines, and corrective 
actions if necessary. The NPRM also proposed to reduce certain 
thresholds and intervals required by AD 2004-18-06. The SNPRM proposed 
to revise the NPRM by reducing the proposed repetitive inspection 
intervals.

Comments

    We gave the public the opportunity to participate in developing 
this AD. The following presents the comments received on the SNPRM (77 
FR 61550, October 10, 2012) and the FAA's response to each comment.

Request To Change Certain Repetitive Inspection Intervals

    Boeing asked that the repetitive inspection interval of 1,800 
flight cycles or 1,800 flight hours, as specified in paragraph (r) of 
the SNPRM (77 FR 61550, October 10, 2012), be changed to eliminate the 
1,800 flight-hour interval. Boeing stated that the longitudinal chem-
milled cracks are driven primarily by hoop loading as a result of 
pressurization cycles, and added that the vertical chem-milled cracks 
are driven by both pressure and flight loads. Boeing added that the 
threshold and repetitive inspection intervals can be affected by this. 
Boeing noted that repeating the inspection at 1,800 flight cycles at 
the butt joints was a conservative estimate obtained from crack growth 
data of longitudinal chem-milled cracks; this is conservative because 
the stresses in the skins at the butt joints are lower than the hoop 
stresses, which cause the longitudinal cracks to develop and grow. 
Boeing concluded that a detailed analysis of the stresses on the 
vertical cracks compared with the horizontal cracks confirmed that 
repeating the inspections every 1,800 flight cycles is adequate to 
detect cracks before they spread and result in an unsafe condition.
    We agree that eliminating the 1,800-flight-hour aspect of the 
repetitive inspection interval and the threshold is acceptable for the 
reasons provided by the commenter. We have determined that this change 
adequately addresses the identified unsafe condition. Therefore, we 
have changed paragraph (r) of this final rule accordingly.

Requests To Clarify Exception to Service Information

    Boeing and Southwest Airlines (SWA) asked that we clarify the 
exception language identified in paragraph (o) of the SNPRM (77 FR 
61550, October 10, 2012). Boeing and SWA both suggested language for 
changing that paragraph.
    Boeing stated that the language in paragraph (o) of the SNPRM (77 
FR 61550, October 10, 2012) gives relief for inspections under FAA-
approved repair doublers that span the chem-milled step by a minimum of 
three rows of fasteners above and below the chem-milled step. Boeing 
added that paragraph (o) of the SNPRM does not distinguish the reason 
for the repair (i.e., cracks, dents, corrosion, etc.), but just 
specifies that a repair doubler exists and spans the chem-milled step 
with a sufficient number of fastener rows. Boeing asked that this same 
allowance be given to chem-milled steps under repairs that are 
accomplished according to the general skin repairs specified in 
paragraph (k) of the SNPRM. Boeing noted that paragraph (k) of the 
SNPRM already has language that terminates inspections under repairs 
accomplished according to paragraph (k) of the SNPRM; however, 
paragraph (k) of the SNPRM is for the repair of chem-milled step cracks 
only, so it would not terminate future chem-milled steps under a repair 
that is installed for some reason other than chem-milled cracking.
    SWA stated certain conditions for external repairs are not 
stipulated in paragraph (o) of the SNPRM (77 FR 61550, October 10, 
2012). SWA noted that for airplanes on which the repair does not meet 
these conditions, paragraph (o) of the SNPRM specifies that one option 
to comply with the inspections is to use the Work Instructions of 
Boeing Alert Service Bulletin 737-53A1210, Revision 3, dated July 16, 
2009. SWA added that the option to use an alternate inspection is given 
in the notes section of Tables 1 through 6 of paragraph 1.E., 
``Compliance,'' of Boeing Alert Service Bulletin 737-53A1210, Revision 
3, dated July 16, 2009, rather than in the Work Instructions of this 
service bulletin. SWA also asked that we change the language in 
paragraphs (p), (q), and (r) of the SNPRM for the alternate inspection 
given in Tables 1 through 6 of paragraph 1.E., ``Compliance'' of this 
service bulletin.
    We agree that clarification of the language in paragraph (o) of 
this final rule is necessary to ensure that all inspection requirements 
are complied with as written. We have revised the language in paragraph 
(o) of this final rule to include the language ``or repairs that have a 
minimum of 2 rows of fasteners above and below the chem-milled step, 
and have been installed in accordance with the requirements of 
paragraph (k) of this final rule.'' We have also included language for 
repairs to the vertical chem-milled steps. In addition, we have revised 
paragraph (o) of this final rule to refer to the notes in Tables 1 
through 6 of paragraph 1.E., ``Compliance,'' of Boeing Alert Service 
Bulletin 737-53A1210, Revision 3, dated July 16, 2009, for the 
inspection requirements. With this clarification added to paragraph (o) 
of this final rule, it is not necessary to change the language in 
paragraphs (p) and (q) of this final rule. We have added the exception 
specified in paragraph (o) of this final rule to paragraphs (r), (s), 
(t), and (u) of this final rule.

Request To Clarify Certain Repetitive Inspection Intervals

    SWA asked that we clarify the repetitive inspection intervals 
required by paragraph (h) of the SNPRM (77 FR 61550, October 10, 2012). 
SWA stated that paragraph (h) of the SNPRM includes a new repetitive 
inspection interval for doing the inspections of the lower lobe and 
section 41, and that repeating those inspections every 4,500 flight 
cycles is a new requirement. SWA added that paragraph (s) of the SNPRM 
introduces a new repetitive inspection interval of 1,800 flight cycles 
for the inspections of the lower lobe and section 41, which contradicts 
paragraph (h) of the SNPRM.
    SWA stated that paragraph (s) of the SNPRM (77 FR 61550, October 
10, 2012) introduces the terminology ``areas of known cracking'' and 
``areas of no known cracking'' for inspections of the lower lobe and 
section 41. SWA added that, for areas of known cracking, the 
inspections are required at the latest of the times specified in 
paragraphs (s)(2)(i) and (s)(2)(ii) of the SNPRM. SWA stated that 
paragraph (s)(2)(i) of the SNPRM specifies inspections before the 
accumulation of 35,000 total flight cycles; paragraph (s)(2)(ii) of the 
SNPRM specifies inspections within 4,500 flight cycles after the most 
recent inspection required by paragraph (h) of the SNPRM or within 
1,800 flight cycles after the effective date of the AD, whichever is 
earlier. SWA noted that although paragraph (h) of the SNPRM includes 
the new requirement of

[[Page 60662]]

repeating those inspections every 4,500 flight cycles, airplanes are 
still subject to the existing repetitive inspection interval of 9,000 
flight cycles, as required by AD 2004-18-06, Amendment 39-13784 (69 FR 
54206, September 8, 2004). SWA added that this is a significant 
conflict since airplanes on which the inspection threshold specified in 
paragraph (s)(2)(i) of the SNPRM has been surpassed ``will immediately 
be rendered out of compliance by paragraph (s)(2)(ii) if the most 
recent inspection was accomplished more than 4,500 flight cycles from 
the last inspection.'' SWA also asked that we clarify the inspection 
requirements for airplanes that have accumulated more than 35,000 total 
flight cycles as of the effective date of the AD.
    Boeing stated that paragraph (s)(2)(ii) of the SNPRM (77 FR 61550, 
October 10, 2012) gives a grace period to start inspections in lower 
lobe and section 41 for areas of known cracking for airplanes that have 
exceeded the threshold of 35,000 total flight cycles. Boeing added that 
this grace period is 4,500 flight cycles from the previous inspections 
done in accordance with AD 2004-18-06, Amendment 39-13784 (69 FR 54206, 
September 8, 2004), which required that those areas be re-inspected at 
9,000 flight-cycle intervals. Boeing noted that, as a result of this, 
it is likely that many airplanes will be grounded. Boeing asked that 
the grace period be changed to 9,000 flight cycles.
    We agree that paragraphs (h) and (s) of this final rule should be 
changed since the new requirements could put airplanes out of 
compliance. We have revised paragraph (h) of this final rule to specify 
a repetitive inspection interval of 9,000 flight cycles, as required by 
AD 2004-18-06, Amendment 39-13784 (69 FR 54206, September 8, 2004), and 
have deleted paragraphs (h)(1) and (h)(2) of this final rule to 
eliminate those repetitive inspection intervals.
    We have also revised paragraph (s)(2) of this final rule to include 
the existing repetitive inspection interval of 9,000 flight cycles so 
that no airplanes will be out of compliance with the inspection 
requirements carried over from AD 2004-18-06, Amendment 39-13784 (69 FR 
54206, September 8, 2004).

Request To Update Structural Repair Manual (SRM) References

    SWA asked that we update the SRM repair references in paragraphs 
(k)(2) and (k)(4) of the SNPRM (77 FR 61550, October 10, 2012). SWA 
stated that the references to Figure 229 for Revisions 92 and 70, both 
dated November 10, 2010, in those paragraphs is incorrect. SWA noted 
that the correct repair for those SRM revisions is Repair 31.
    We agree that this final rule should refer to the latest repairs. 
We have determined that the SRM repair references specified in 
paragraphs (k)(2) and (k)(4) of the SNPRM (77 FR 61550, October 10, 
2012), have been updated. The SRM repair reference in paragraph (k)(3) 
of the SNPRM also has been updated. Therefore, we have changed 
paragraphs (k)(2), (k)(3), and (k)(4) of this final rule to update the 
SRM references to include the appropriate repair.

Request To Clarify Terminating Action

    SWA asked that we change paragraph (j)(1)(i) of the SNPRM (77 FR 
61550, October 10, 2012) to reflect that the time-limited repair 
specified in that paragraph terminates the repetitive inspections 
required by paragraph (g) of the SNPRM. SWA also asked that, if we do 
not change that paragraph, we provide clarification that accomplishment 
of the repair specified in paragraph (v) of the SNPRM terminates those 
repetitive inspections. SWA stated that paragraph (j) of the SNPRM 
addresses retained corrective actions for cracking found during the 
inspections required by paragraphs (g), (h), (p), (q), (r), and (s) of 
the SNPRM. SWA added that paragraph (v) of the SNPRM specifies that 
accomplishment of the permanent repair specified in Part 5, or the 
time-limited repair specified in Part 6, of the Accomplishment 
Instructions of Boeing Alert Service Bulletin 737-53A1210, Revision 3, 
dated July 16, 2009, terminates the repetitive inspections required by 
paragraphs (p), (q), (r), and (s) of the SNPRM for the repaired area 
only. SWA noted that paragraph (j)(1)(i) of the SNPRM specifies that 
installation of a permanent repair terminates the repetitive 
inspections required by paragraph (g) of the SNPRM for the repaired 
area only; however, paragraph (j)(1)(i) of the SNPRM does not indicate 
that accomplishing the time-limited repair terminates the repetitive 
inspections.
    We agree that clarification is necessary. Since the crack at the 
chem-milled step has been trimmed out during installation of the time-
limited repair in accordance with Boeing Alert Service Bulletin 737-
53A1210, Revision 3, dated July 16, 2009, the inspections required by 
paragraph (g) of this final rule cannot be accomplished. We have 
changed paragraph (j)(1)(i) of this final rule to specify 
``Installation of a time-limited repair ends the repetitive inspections 
required by paragraph (g) of this final rule for the repaired area 
only.'' We have also added a reference to paragraph (j)(1)(i) of this 
final rule in paragraph (g) of this final rule to specify that the 
actions specified in paragraph (j)(1)(i) of this final rule terminate 
the repetitive inspections.

Additional Changes Made to This Final Rule

    We have removed paragraph (b)(2) of the SNPRM (77 FR 61550, October 
10, 2012) from this final rule, because the ADs that were identified in 
paragraph (b)(2) of the SNPRM are not ``affected'' by this AD. We have 
also redesignated paragraph (b)(1) of the SNPRM as paragraph (b) of 
this final rule. These changes do not affect the intent of this AD.
    We have revised the wording in paragraph (n) 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 
this AD with the changes described previously--and minor editorial 
changes. We have determined that these minor changes:
     [Agr]re consistent with the intent that was proposed in 
the SNPRM (77 FR 61550, October 10, 2012) for correcting the unsafe 
condition; and
     Do not add any additional burden upon the public than was 
already proposed in the SNPRM (77 FR 61550, October 10, 2012).
    We also determined that these changes will not increase the 
economic burden on any operator or increase the scope of this AD.

Costs of Compliance

    We estimated that 903 airplanes of U.S. registry are affected by AD 
2004-18-06, Amendment 39-13784 (69 FR 54206, September 8, 2004).
    The inspections of the crown area that are retained from AD 2004-
18-06, Amendment 39-13784 (69 FR 54206, September 8, 2004), take about 
94 work-hours per airplane to accomplish, at an average labor rate of 
$85 per work-hour. Based on these figures, the estimated cost of the 
retained inspections is $7,990 per airplane, per inspection cycle.
    The inspections of the lower lobe area that are retained from AD 
2004-18-06, Amendment 39-13784 (69 FR 54206, September 8, 2004), take 
about 96 work-hours per airplane to accomplish, at an average labor 
rate of $85 per work-hour. Based on these figures, the estimated cost 
of the retained inspections is

[[Page 60663]]

$8,160 per airplane, per inspection cycle.
    Should an operator elect to install the preventive modification 
specified in AD 2004-18-06, Amendment 39-13784 (69 FR 54206, September 
8, 2004), it will take about 108 work-hours per airplane to accomplish, 
at an average labor rate of $85 per work-hour. Based on these figures, 
the estimated cost of the modification is $9,180 per airplane.
    We estimate that this AD affects about 701 airplanes of U.S. 
registry.
    The new inspections take about 27 work-hours per airplane, at an 
average labor rate of $85 per work-hour. Based on these figures, the 
estimated cost of the new actions specified in this AD for U.S. 
operators is $1,608,795, or $2,295 per airplane, per inspection cycle.

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 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.

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) 
2004-18-06, Amendment 39-13784 (69 FR 54206, September 8, 2004), and 
adding the following new AD:

2013-18-08 The Boeing Company: Amendment 39-17581; Docket No. FAA-
2011-0155; Directorate Identifier 2009-NM-141-AD.

(a) Effective Date

    This AD is effective November 6, 2013.

(b) Affected ADs

    This AD supersedes AD 2004-18-06, Amendment 39-13784 (69 FR 
54206, September 8, 2004).

(c) Applicability

    This AD applies to The Boeing Company Model 737-200, -200C, -
300, -400, and -500 series airplanes, certificated in any category, 
as identified in Boeing Alert Service Bulletin 737-53A1210, Revision 
3, dated July 16, 2009.

(d) Subject

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

(e) Unsafe Condition

    This AD was prompted by new findings of vertical cracks along 
chem-milled steps adjacent to the butt joints. We are issuing this 
AD to detect and correct fatigue cracking of the skin panels, which 
could result in sudden fracture and failure of the skin panels of 
the fuselage, and consequent rapid decompression of the airplane.

(f) Compliance

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

(g) Retained External Detailed and Eddy Current Inspections

    This paragraph restates the requirements of paragraph (a) of AD 
2004-18-06, Amendment 39-13784 (69 FR 54206, September 8, 2004), 
with revised service information. For Groups 1 through 5 airplanes 
identified in Boeing Alert Service Bulletin 737-53A1210, Revision 1, 
dated October 25, 2001: Before the accumulation of 35,000 total 
flight cycles, or within 4,500 flight cycles after October 13, 2004 
(the effective date of AD 2004-18-06), whichever is later, do 
external detailed and eddy current inspections of the crown area and 
other known areas of fuselage skin cracking, in accordance with Part 
1 and Figure 1 of the Work Instructions of Boeing Alert Service 
Bulletin 737-53A1210, Revision 1, dated October 25, 2001; or in 
accordance with Part 1 of the Accomplishment Instructions of Boeing 
Alert Service Bulletin 737-53A1210, Revision 3, dated July 16, 2009; 
except as provided by paragraph (o) of this AD. Repeat the external 
detailed and eddy current inspections at intervals not to exceed 
4,500 flight cycles until paragraph (i), (j)(1)(i), (j)(1)(ii), (k), 
(l), or (m) of this AD has been done, as applicable. Although 
paragraph 1.D. of Boeing Alert Service Bulletin 737-53A1210, 
Revision 1, dated October 25, 2001, references a reporting 
requirement, such reporting is not required by this AD. 
Accomplishing the actions required by paragraph (p) or (q) of this 
AD ends the repetitive requirements in this paragraph.

(h) Retained External Detailed Inspection With Reduced Compliance Time

    This paragraph restates the requirements of paragraph (b) of AD 
2004-18-06, Amendment 39-13784 (69 FR 54206, September 8, 2004), 
with reduced compliance time and revised service information. For 
all airplanes identified in Boeing Alert Service Bulletin 737-
53A1210, Revision 1, dated October 25, 2001: Before the accumulation 
of 40,000 total flight cycles, or within 4,500 flight cycles after 
October 13, 2004 (the effective date of AD 2004-18-06), whichever is 
later, do an external detailed inspection of the lower lobe area and 
section 41 of the fuselage for cracking, in accordance with Part 2 
and Figure 2 of the Work Instructions of Boeing Alert Service 
Bulletin 737-53A1210, Revision 1, dated October 25, 2001; or in 
accordance with Part 4 of the Accomplishment Instructions of Boeing 
Alert Service Bulletin 737-53A1210, Revision 3, dated July 16, 2009; 
except as provided by paragraph (o) of this AD. Repeat the 
inspection thereafter at intervals not to exceed 9,000 flight cycles 
until the actions specified in paragraph (j)(2) or paragraph (k), as 
applicable, of this AD have been done. Accomplishing the actions 
required by paragraph (s) of this AD ends the requirements in this 
paragraph.

(i) Retained Preventive Modification at Stringer 12

    This paragraph restates the requirements of paragraph (c) of AD 
2004-18-06, Amendment 39-13784 (69 FR 54206, September 8, 2004), 
with revised service information. For Groups 3 and 5 airplanes 
identified in Boeing Alert Service Bulletin 737-53A1210, Revision 1, 
dated October 25, 2001: If no cracking is found during any 
inspection required by paragraph (g) of this AD, doing the 
preventive modification of the chem-milled pockets in the upper 
skin, as

[[Page 60664]]

specified in Part 5 of the Work Instructions of Boeing Alert Service 
Bulletin 737-53A1210, Revision 1, dated October 25, 2001; or as 
specified in Part 7 of the Work Instructions of Boeing Alert Service 
Bulletin 737-53A1210, Revision 3, dated July 16, 2009, except as 
required by paragraph (x) of this AD; ends the repetitive external 
detailed and eddy current inspections required by paragraph (g) of 
this AD for the modified area only. As of the effective date of this 
AD, use only Boeing Alert Service Bulletin 737-53A1210, Revision 3, 
dated July 16, 2009, to do the actions required by this paragraph.

(j) Retained Corrective Actions

    This paragraph restates the requirements of paragraph (d) of AD 
2004-18-06, Amendment 39-13784 (69 FR 54206, September 8, 2004), 
with revised service information. If any cracking is found during 
any inspection required by paragraph (g), (h), (p), (q), or (s) of 
this AD, before further flight, do the actions specified in 
paragraphs (j)(1) and (j)(2) of this AD, as applicable, in 
accordance with the Work Instructions of Boeing Alert Service 
Bulletin 737-53A1210, Revision 1, dated October 25, 2001; or in 
accordance with the Work Instructions of Boeing Alert Service 
Bulletin 737-53A1210, Revision 3, dated July 16, 2009. As of the 
effective date of this AD, use only Boeing Alert Service Bulletin 
737-53A1210, Revision 3, dated July 16, 2009, to do the actions 
required by this paragraph. Where Boeing Alert Service Bulletin 737-
53A1210, Revision 1, dated October 25, 2001; or Boeing Alert Service 
Bulletin 737-53A1210, Revision 3, dated July 16, 2009; specify to 
contact Boeing for repair instructions, before further flight, 
repair in accordance with a method approved by the Manager, Seattle 
Aircraft Certification Office (ACO), FAA; or in accordance with data 
meeting the type certification basis of the airplane if it is 
approved by the Boeing Commercial Airplanes Organization Designation 
Authorization (ODA) or any other person 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.
    (1) Except as provided by paragraph (k) of this AD, for cracking 
of the crown area, do the repair specified in either paragraph 
(j)(1)(i) or (j)(1)(ii) of this AD.
    (i) Do a time-limited repair in accordance with Part 4 of the 
Work Instructions of Boeing Alert Service Bulletin 737-53A1210, 
Revision 1, dated October 25, 2001; or in accordance with Part 6 of 
the Work Instructions of Boeing Alert Service Bulletin 737-53A1210, 
Revision 3, dated July 16, 2009, except as required by paragraph (x) 
of this AD; then do the actions required by paragraph (l) of this AD 
at the times specified in that paragraph. Installation of a time-
limited repair ends the repetitive inspections required by paragraph 
(g) of this AD for the repaired area only.
    (ii) Do a permanent repair in accordance with Part 3 of the Work 
Instructions of Boeing Alert Service Bulletin 737-53A1210, Revision 
1, dated October 25, 2001; or in accordance with Part 5 of the Work 
Instructions of Boeing Alert Service Bulletin 737-53A1210, Revision 
3, dated July 16, 2009. Installation of a permanent repair ends the 
repetitive inspections required by paragraph (g) of this AD for the 
repaired area only. Installation of the lap joint repair specified 
in paragraph (g) of AD 2002-07-08, Amendment 39-12702 (67 FR 17917, 
April 12, 2002), is considered acceptable for compliance with the 
corresponding permanent repair specified in this paragraph for the 
repaired areas only.
    (2) Except as provided by paragraph (k) of this AD, for cracking 
of the lower lobe area and section 41, repair in accordance with 
Part 2 of the Work Instructions of Boeing Alert Service Bulletin 
737-53A1210, Revision 1, dated October 25, 2001; or in accordance 
with paragraph (j)(2)(i) or (j)(2)(ii) of this AD. Accomplishment of 
this repair ends the repetitive inspections required by paragraph 
(h) of this AD for the repaired area only. As of the effective date 
of this, do the repair specified in paragraph (j)(2)(i) or 
(j)(2)(ii) of this AD.
    (i) Do a time-limited repair in accordance with Part 6 of the 
Work Instructions of Boeing Alert Service Bulletin 737-53A1210, 
Revision 3, dated July 16, 2009, except as required by paragraph (x) 
of this AD, then do the actions required by paragraph (l) of this AD 
at the times specified in that paragraph.
    (ii) Do a permanent repair in accordance with Part 5 of the 
Accomplishment Instructions of Boeing Alert Service Bulletin 737-
53A1210, Revision 3, dated July 16, 2009.

(k) Retained Optional Repair Method

    This paragraph restates the requirements of paragraph (e) of AD 
2004-18-06, Amendment 39-13784 (69 FR 54206, September 8, 2004), 
with revised service information. For cracking in any area specified 
in paragraphs (j)(1) and (j)(2) of this AD within the limitations of 
the applicable structural repair manual (SRM) specified in 
paragraphs (k)(1) through (k)(4) of this AD, repair any cracks, in 
accordance with a method approved by the Manager, Seattle ACO; or in 
accordance with data meeting the type certification basis of the 
airplane if it is approved by the Boeing Commercial Airplanes ODA or 
any other person 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. Accomplishment of the applicable 
repair terminates the repetitive inspections required by paragraphs 
(g) and (h) of this AD for the repaired area only. Guidance on 
repairing the cracking can be found in the applicable SRM specified 
in paragraphs (k)(1) through (k)(4) of this AD.
    (1) For Model 737-100, -200 series airplanes: Figure 48, General 
Fuselage Skin Repair, of Subject 53-30-3, Skin Repair, of Chapter 
53, Fuselage, of the Boeing 737-100/-200 SRM D6-15565, Revision 102, 
dated September 10, 2010.
    (2) For Model 737-300 series airplanes: Repair 31, General 
Fuselage Skin Repairs, of Subject 53-00-01, Fuselage Skin--General, 
of Chapter 53, Fuselage, of the Boeing 737-300 SRM D6-37635, 
Revision 92, dated November 10, 2010.
    (3) For Model 737-400 series airplanes: Repair 31, General 
Fuselage Skin Repairs, of Subject 53-00-01, Fuselage Skin--General, 
of Chapter 53, Fuselage, of the Boeing 737-400 SRM D6-38246, 
Revision 75, dated November 10, 2010.
    (4) For Model 737-500 series airplanes: Repair 31, General 
Fuselage Skin Repairs, of Subject 53-00-01, Fuselage Skin--General, 
of Chapter 53, Fuselage, of the Boeing 737-500 SRM D6-38441, 
Revision 70, dated November 10, 2010.

(l) Retained Follow-On and Corrective Actions

    This paragraph restates the requirements of paragraph (f) of AD 
2004-18-06, Amendment 39-13784 (69 FR 54206, September 8, 2004), 
with revised service information. If a time-limited repair is done, 
as specified in paragraph (j)(1)(i) or (j)(2)(i) of this AD: Do the 
actions specified in paragraphs (l)(1), (l)(2), and (l)(3) of this 
AD, at the times specified in paragraphs (l)(1), (l)(2), and (l)(3) 
of this AD, in accordance with the Work Instructions of Boeing Alert 
Service Bulletin 737-53A1210, Revision 1, dated October 25, 2001; or 
in accordance with the Work Instructions of Boeing Alert Service 
Bulletin 737-53A1210, Revision 3, dated July 16, 2009.
    (1) Within 3,000 flight cycles after doing the repair: Do the 
actions specified in paragraph (l)(1)(i) or (l)(1)(ii) of this AD. 
Then repeat the applicable inspection specified in paragraph 
(l)(1)(i) or (l)(1)(ii) of this AD at intervals not to exceed 3,000 
flight cycles until permanent rivets are installed in the repaired 
area, which ends the repetitive inspections for this paragraph. As 
of the effective date of this AD, do only the inspections specified 
in paragraph (l)(1)(ii) of this AD.
    (i) For repairs done before the effective date of this AD: Do a 
detailed inspection of the repaired area for loose fasteners in 
accordance with Part 4 of the Work Instructions of Boeing Alert 
Service Bulletin 737-53A1210, Revision 1, dated October 25, 2001, or 
do the actions specified in paragraph (l)(1)(ii) of this AD. If any 
loose fastener is found, before further flight, replace with a new 
fastener, in accordance with the Work Instructions of Boeing Alert 
Service Bulletin 737-53A1210, Revision 1, dated October 25, 2001.
    (ii) For repairs done after the effective date of this AD: Do a 
detailed inspection of the repaired area for loose, damaged, and 
missing fasteners, in accordance with Part 6 of the Work 
Instructions of Boeing Alert Service Bulletin 737-53A1210, Revision 
3, dated July 16, 2009. If any loose, missing, or damaged fastener 
is found, before further flight, replace with a new fastener, in 
accordance with the Work Instructions of Boeing Alert Service 
Bulletin 737-53A1210, Revision 3, dated July 16, 2009.
    (2) At the applicable time specified in paragraph (l)(2)(i) and 
(l)(2)(ii) of this AD: Do inspections of the repaired area for 
cracking in accordance with Part 4 of the Work Instructions of 
Boeing Alert Service Bulletin 737-53A1210, Revision 1, dated October 
25,

[[Page 60665]]

2001; or in accordance with Part 6 of the Work Instructions of 
Boeing Alert Service Bulletin 737-53A1210, Revision 3, dated July 
16, 2009. If any cracking is found, before further flight, repair in 
accordance with a method approved by the Manager, Seattle ACO, or in 
accordance with data meeting the type certification basis of the 
airplane if it is approved by the Boeing Commercial Airplanes ODA or 
any other person 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.
    (i) For repairs done before the effective date of this AD: 
Within 4,000 flight cycles after doing the repair, do the 
inspections.
    (ii) For repairs done on or after the effective date of this AD: 
Within 3,000 flight cycles after doing the repair, do the 
inspections.
    (3) At the earlier of the times specified in paragraphs 
(l)(3)(i) and (l)(3)(ii) of this AD: Make the repair permanent in 
accordance with Part 4 and Figure 20 of the Work Instructions of 
Boeing Alert Service Bulletin 737-53A1210, Revision 1, dated October 
25, 2001, or do the permanent repair, in accordance with Part 5 of 
the Work Instructions of Boeing Alert Service Bulletin 737-53A1210, 
Revision 3, dated July 16, 2009, which ends the repetitive 
inspections for the repaired area only. As of the effective date of 
this AD, only Boeing Alert Service Bulletin 737-53A1210, Revision 3, 
dated July 16, 2009, may be used to make the repair permanent.
    (i) Within 10,000 flight cycles after doing the repair in 
accordance with Boeing Alert Service Bulletin 737-53A1210, Revision 
1, dated October 25, 2001.
    (ii) At the later of the times specified in paragraphs 
(l)(3)(ii)(A) and (l)(3)(ii)(B) of this AD.
    (A) Within 6,000 flight cycles after doing the repair.
    (B) Within 1,000 flight cycles after the effective date of this 
AD.

(m) Retained Optional Terminating Action for Repetitive Eddy Current 
Inspections

    This paragraph restates the requirements of paragraph (g) of AD 
2004-18-06, Amendment 39-13784 (69 FR 54206, September 8, 2004), 
with revised service information. Accomplishment of paragraph (b) or 
(c), as applicable, of AD 2003-14-06, Amendment 39-13225 (68 FR 
42956, July 21, 2003), before the effective date of this AD ends the 
repetitive eddy current inspections required by paragraph (g) of 
this AD for that skin panel only; however, the repetitive external 
detailed inspections required by paragraph (g) of this AD are still 
required for all areas. Accomplishing paragraph (b) or (c), as 
applicable, of AD 2003-14-06, on or after the effective date of this 
AD, does not end either the repetitive detailed or eddy current 
inspections required by paragraph (g) of this AD.

(n) Retained Credit for Previous Actions

    This paragraph restates the provisions of paragraph (h) of AD 
2004-18-06, Amendment 39-13784 (69 FR 54206, September 8, 2004). 
This paragraph provides credit for actions specified by paragraphs 
(g), (h), (i), (j), (k), and (l) of this AD, if those actions were 
done before October 13, 2004 (the effective date of AD 2004-18-06), 
using Boeing Alert Service Bulletin 737-53A1210, dated December 14, 
2000 (which is not incorporated by reference in this AD).

(o) Retained Exception to Service Bulletin Procedures

    This paragraph restates the provision of paragraph (i) of AD 
2004-18-06, Amendment 39-13784 (69 FR 54206, September 8, 2004), 
with revised service information. For airplanes subject to the 
requirements of paragraphs (g) and (h) of this AD: Inspections are 
not required in areas that are spanned by an FAA-approved repair 
that has a minimum of 3 rows of fasteners above and below, or 
forward and aft of the chem-milled step, or repairs that have a 
minimum of 2 rows of fasteners above and below, or forward and aft 
of the chem-milled step, and have been installed in accordance with 
the requirements of paragraph (k) of this AD. If an external doubler 
covers the chem-milled step, but does not span it by a minimum of 3 
rows of fasteners above and below, or forward and aft, or does not 
have a minimum of 2 rows of fasteners above and below, and have been 
installed in accordance with the requirements of paragraph (k) of 
this AD: In lieu of requesting approval for an alternative method of 
compliance (AMOC), one option to comply with the inspection 
requirement of paragraphs (g) and (h) of this AD is to inspect all 
chem-milled steps covered by the repair using the method specified 
in the notes in Tables 1 through 6 of paragraph 1.E., 
``Compliance,'' and in accordance with the Work Instructions, of 
Boeing Alert Service Bulletin 737-53A1210, Revision 3, dated July 
16, 2009.

(p) For Certain Airplanes: New Repetitive External Detailed and Eddy 
Current Inspections of the Crown Area and Other Known Areas of Fuselage 
Skin Cracking, and Corrective Actions

    For Groups 1 through 5 and Groups 9 through 21 airplanes 
identified in Boeing Alert Service Bulletin 737-53A1210, Revision 3, 
dated July 16, 2009, on which the inspections required by paragraph 
(g) of this AD have been done before the effective date of this AD: 
Within 4,500 flight cycles after doing the most recent inspection 
required by paragraph (g) of this AD, or within 1,800 flight cycles 
after the effective date of this AD, whichever is earlier; do 
external detailed and eddy current inspections of the crown area and 
other known areas of the fuselage skin cracking, in accordance with 
Part 1 of the Accomplishment Instructions of Boeing Alert Service 
Bulletin 737-53A1210, Revision 3, dated July 16, 2009; except as 
provided by paragraph (o) of this AD. Repeat the external detailed 
and eddy current inspections thereafter at intervals not to exceed 
1,800 flight cycles. Accomplishing the inspections required by this 
paragraph ends the repetitive inspections required by paragraph (g) 
of this AD. Before further flight, do all applicable corrective 
actions as specified in paragraph (j) of this AD. For the locations 
specified in Boeing Alert Service Bulletin 737-53A1210, Revision 3, 
dated July 16, 2009, in lieu of doing detailed inspections, 
operators may do general visual inspections, provided that the 
general visual inspections are done at intervals not to exceed 1,000 
flight cycles.

(q) For Certain Other Airplanes: New Repetitive External Detailed and 
Eddy Current Inspections of the Crown Area and Other Known Areas of 
Fuselage Skin Cracking, and Corrective Actions

    For Groups 1 through 5 and 9 through 21 airplanes identified in 
Boeing Alert Service Bulletin 737-53A1210, Revision 3, dated July 
16, 2009, on which the inspections required by paragraph (g) of this 
AD have not been done before the effective date of this AD: Before 
the accumulation of 28,000 total flight cycles, or within 1,800 
flight cycles after the effective date of this AD, whichever is 
later, do external detailed and eddy current inspections of the 
crown area and other known areas of fuselage skin cracking, in 
accordance with Part 1 of the Accomplishment Instructions of Boeing 
Alert Service Bulletin 737-53A1210, Revision 3, dated July 16, 2009, 
except as provided by paragraph (o) of this AD. Repeat the external 
detailed and eddy current inspections thereafter at intervals not to 
exceed 1,800 flight cycles. Accomplishing the inspections required 
by this paragraph ends the repetitive inspections required by 
paragraph (g) of this AD. Before further flight, do all applicable 
corrective actions as specified in paragraph (j) of this AD. For the 
locations specified in Boeing Alert Service Bulletin 737-53A1210, 
Revision 3, dated July 16, 2009, in lieu of doing detailed 
inspections, operators may do general visual inspections, provided 
that the general visual inspections are done at intervals not to 
exceed 1,000 flight cycles.

(r) New Repetitive External Detailed and Eddy Current Inspections of 
the Fuselage Skin Along the Chem-Milled Steps of the Butt Joints, and 
Corrective Actions

    For Groups 1 through 5, and 9 through 21 airplanes identified in 
Boeing Alert Service Bulletin 737-53A1210, Revision 3, dated July 
16, 2009: At the later of the times specified in paragraphs (r)(1) 
and (r)(2) of this AD, do external detailed and eddy current 
inspections for vertical cracks in the fuselage skin along the chem-
milled steps of the butt joints, in accordance with Part 3 of the 
Accomplishment Instructions of Boeing Alert Service Bulletin 737-
53A1210, Revision 3, dated July 16, 2009, except as provided by 
paragraph (o) of this AD. Repeat the inspections thereafter at 
intervals not to exceed 1,800 flight cycles. If any cracking is 
found, before further flight, repair in accordance with Part 5 of 
the Accomplishment Instructions of Boeing Alert Service Bulletin 
737-53A1210, Revision 3, dated July 16, 2009. Doing the repair 
terminates the repetitive inspections specified in this paragraph 
for the repaired area only.
    (1) Before the accumulation of 55,000 total flight cycles or 
55,000 total flight hours, whichever occurs first.
    (2) Within 1,800 flight cycles after the effective date of this 
AD.

[[Page 60666]]

(s) New Repetitive Detailed and Eddy Current Inspections Along the 
Chem-Milled Lines of the Fuselage Skin of the Lower Lobe Area and 
Section 41, and Corrective Actions

    For Groups 1 through 21 airplanes identified in Boeing Alert 
Service Bulletin 737-53A1210, Revision 3, dated July 16, 2009: At 
the applicable time specified in paragraph (s)(1) or (s)(2) of this 
AD, do external detailed and eddy current inspections, as 
applicable, for horizontal cracks along the chem-milled lines of the 
fuselage skin of the lower lobe area and section 41, in accordance 
with Part 4 of the Accomplishment Instructions of Boeing Alert 
Service Bulletin 737-53A1210, Revision 3, dated July 16, 2009, 
except as provided by paragraphs (o) and (x) of this AD. Repeat the 
inspections thereafter at intervals not to exceed 1,800 flight 
cycles. Accomplishing the inspections required by this paragraph 
ends the inspections required by paragraph (h) of this AD. Before 
further flight, do all applicable corrective actions as specified in 
paragraph (j) of this AD. For the locations specified in Boeing 
Alert Service Bulletin 737-53A1210, Revision 3, dated July 16, 2009, 
in lieu of doing detailed inspections, operators may do general 
visual inspections, provided that the general visual inspections are 
done at intervals not to exceed 1,000 flight cycles.
    (1) Before the accumulation of 35,000 total flight cycles.
    (2) Within 9,000 flight cycles after the most recent inspection 
required by paragraph (h) of this AD, or within 1,800 flight cycles 
after the effective date of this AD, whichever is earlier.

(t) For Certain Airplanes: New Repetitive External Detailed and Eddy 
Current Inspections Along the Chem-Milled Lines of the Fuselage Skin of 
the Window Belt Area, and Corrective Actions

    For Groups 4, 11, and 16 airplanes identified in Boeing Alert 
Service Bulletin 737-53A1210, Revision 3, dated July 16, 2009: 
Before the accumulation of 25,000 total flight cycles or within 
1,800 flight cycles after the effective date of this AD, whichever 
is later, do external detailed and eddy current inspections for 
horizontal cracks along the chem-milled lines of the fuselage skin 
of the fuselage window belt area, in accordance with Part 2 of the 
Accomplishment Instructions of Boeing Alert Service Bulletin 737-
53A1210, Revision 3, dated July 16, 2009, except as provided by 
paragraph (o) of this AD. Repeat the inspections thereafter at 
intervals not to exceed 1,800 flight cycles. If any cracking is 
found, before further flight, repair using a method approved in 
accordance with the procedures specified in paragraph (y) of this 
AD. Doing the repair terminates the repetitive inspections specified 
in this paragraph for the repaired area only.

(u) For Certain Other Airplanes: New Repetitive External Detailed and 
Eddy Current Inspections Along the Chem-Milled Lines of the Fuselage 
Skin of the Window Belt Area, and Corrective Actions

    For Groups 3, 5, 9, 10, 12, 14, 15, 17, 18, 19, 20, and 21 
airplanes identified in Boeing Alert Service Bulletin 737-53A1210, 
Revision 3, dated July 16, 2009: Do the actions specified in 
paragraph (u)(1) or (u)(2) of this AD, as applicable. Part 7 (Figure 
10) of the Accomplishment Instructions of Boeing Alert Service 
Bulletin 737-53A1210, Revision 3, dated July 16, 2009, specifies 
applying corrosion inhibiting compound (CIC) Boeing Material 
Specification (BMS) 3-23 to the surfaces of the repaired area. As an 
option to using CIC BMS 3-23, operators may use CIC BMS 3-35, which 
is equivalent to CIC BMS 3-23.
    (1) For airplanes on which the inspections required by paragraph 
(g) of this AD have been done before the effective date of this AD: 
Within 4,500 flight cycles after doing the most recent inspection 
required by paragraph (g) of this AD, or within 1,800 flight cycles 
after the effective date of this AD, whichever is earlier, do 
external detailed and eddy current inspections for horizontal cracks 
along the chem-milled lines of the fuselage skin of the fuselage 
window belt area, in accordance with Part 2 of the Accomplishment 
Instructions of Boeing Alert Service Bulletin 737-53A1210, Revision 
3, dated July 16, 2009, except as provided by paragraph (o) of this 
AD. Repeat the inspections thereafter at intervals not to exceed 
1,800 flight cycles. If any cracking is found, before further 
flight, repair in accordance with Part 8 of the Accomplishment 
Instructions of Boeing Alert Service Bulletin 737-53A1210, Revision 
3, dated July 16, 2009, except as required by paragraph (x) of this 
AD.
    (2) For airplanes on which the inspections required by paragraph 
(g) of this AD have not been done before the effective date of this 
AD: Before the accumulation of 25,000 total flight cycles or within 
1,800 flight cycles after the effective date of this AD, whichever 
is later, do external detailed and eddy current inspections for 
horizontal cracks along the chem-milled lines of the fuselage skin 
of the fuselage window belt area, in accordance with Part 2 of the 
Accomplishment Instructions of Boeing Alert Service Bulletin 737-
53A1210, Revision 3, dated July 16, 2009. Repeat the inspections 
thereafter at intervals not to exceed 1,800 flight cycles. If any 
cracking is found, before further flight, repair in accordance with 
Part 8 of the Accomplishment Instructions of Boeing Alert Service 
Bulletin 737-53A1210, Revision 3, dated July 16, 2009, except as 
required by paragraph (x) of this AD.

(v) New Optional Repair

    For airplanes on which cracking is found during any inspection 
required by paragraph (p), (q), (r), or (s) of this AD, as 
applicable, doing the repair of the chem-milled area in the skin, as 
specified in Part 5 or Part 6 of the Accomplishment Instructions of 
Boeing Alert Service Bulletin 737-53A1210, Revision 3, dated July 
16, 2009, ends the repetitive external detailed and eddy current 
inspections required by paragraph (p), (q), (r), or (s) of this AD, 
as applicable, for the repaired area only.

    Note 1 to paragraph (v) of this AD: Part 8 of the Accomplishment 
Instructions of Boeing Alert Service Bulletin 737-53A1210, Revision 
3, dated July 16, 2009, specifies a post-repair inspection of the 
skin chem-milled crack repair at stringer 12; that inspection is not 
required by this AD. The damage tolerance inspections specified in 
Table 7 of paragraph 1.E., ``Compliance,'' of Boeing Alert Service 
Bulletin 737-53A1210, Revision 3, dated July 16, 2009, may be used 
in support of compliance with section 121.1109(c)(2) or 
129.109(c)(2) of the Code of Federal Regulations (14 CFR 
121.1109(c)(2) or 14 CFR 129.109(c)(2)).

(w) New Optional Preventive Modification at Stringer 12

    For airplanes on which no cracking is found during any 
inspection required by paragraph (u) of this AD, doing the 
preventive modification of the chem-milled areas in the skin at 
stringer 12, as specified in Part 7 of the Accomplishment 
Instructions of Boeing Alert Service Bulletin 737-53A1210, Revision 
3, dated July 16, 2009, except as required by paragraph (x) of this 
AD, ends the repetitive external detailed and eddy current 
inspections required by paragraph (u) of this AD, for the modified 
areas common to stringer 12 only. Part 7 (Figure 10) of the 
Accomplishment Instructions of Boeing Alert Service Bulletin 737-
53A1210, Revision 3, dated July 16, 2009, specifies applying CIC BMS 
3-23 to the surfaces of the repaired area. As an option to using CIC 
BMS 3-23, operators may use CIC BMS 3-35, which is equivalent to CIC 
BMS 3-23.

(x) Exception to Service Information

    Where Boeing Alert Service Bulletin 737-53A1210, Revision 3, 
dated July 16, 2009, specifies to contact Boeing for repair 
instructions, before further flight, repair using a method approved 
in accordance with the procedures specified in paragraph (y) of this 
AD.

(y) 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 paragraph 
(z)(1) of this AD. Information may be emailed to: 9-ANM-Seattle-ACO-AMOC-Requests@faa.gov.
    (2) Before using any approved AMOC, notify your appropriate 
principal 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 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 2004-18-06, 
Amendment 39-13784 (69 FR 54206,

[[Page 60667]]

September 8, 2004), are approved as AMOCs for the corresponding 
provisions of this AD.
    (5) Inspections and corrective actions required by paragraph (g) 
of AD 2009-21-01, Amendment 39-16038 (74 FR 52395, October 13, 
2009), are approved as AMOCs for the corresponding provisions of 
paragraph(s) of this AD, but only for the areas of the lower lobe 
skin identified in AD 2009-21-01.

(z) 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: 
wayne.lockett@faa.gov.
    (2) Service information that is referenced in this AD that is 
not incorporated by reference in this AD may be obtained at the 
addresses identified in paragraphs (aa)(5) and (aa)(6) of this AD.

(aa) 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 for IBR on 
November 6, 2013.
    (i) Boeing Alert Service Bulletin 737-53A1210, Revision 3, dated 
July 16, 2009.
    (ii) Figure 48, General Fuselage Skin Repair, of Subject 53-30-
3, Skin Repair, of Chapter 53, Fuselage, of the Boeing 737-100/-200 
SRM D6-15565, Revision 102, dated September 10, 2010. The revision 
level of this document is identified in only the transmittal letter; 
no other page of the document contains this information.
    (iii) Repair 31, General Fuselage Skin Repairs, of Subject 53-
00-01, Fuselage Skin--General, of Chapter 53, Fuselage, of the 
Boeing 737-300 SRM D6-37635, Revision 92, dated November 10, 2010. 
The revision level of this document is identified in only the 
transmittal letter; no other page of the document contains this 
information.
    (iv) Repair 31, General Fuselage Skin Repairs, of Subject 53-00-
01, Fuselage Skin--General, of Chapter 53, Fuselage, of the Boeing 
737-400 SRM D6-38246, Revision 75, dated November 10, 2010. The 
revision level of this document is identified in only the 
transmittal letter; no other page of the document contains this 
information.
    (v) Repair 31, General Fuselage Skin Repairs, of Subject 53-00-
01, Fuselage Skin--General, of Chapter 53, Fuselage, of the Boeing 
737-500 SRM D6-38441, Revision 70, dated November 10, 2010. The 
revision level of this document is identified in only the 
transmittal letter; no other page of the document contains this 
information.
    (4) The following service information was approved for IBR on 
October 13, 2004 (69 FR 54206, September 8, 2004).
    (i) Boeing Alert Service Bulletin 737-53A1210, Revision 1, 
excluding Appendix A, dated October 25, 2001.
    (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, WA 98124-2207; telephone 206-544-
5000, extension 1; fax 206-766-5680; Internet https://www.myboeingfleet.com.
    (6) You may view this service information at the FAA, Transport 
Airplane Directorate, 1601 Lind Avenue SW., Renton, WA. For 
information on the availability of this material at the FAA, call 
425-227-1221.
    (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: https://www.archives.gov/federal-register/cfr/ibr-locations.html.

    Issued in Renton, Washington, on August 16, 2013.
Jeffrey E. Duven,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2013-24034 Filed 10-1-13; 8:45 am]
BILLING CODE 4910-13-P