[Federal Register Volume 78, Number 6 (Wednesday, January 9, 2013)]
[Proposed Rules]
[Pages 1772-1776]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2013-00186]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2012-1316; Directorate Identifier 2012-NM-186-AD]
RIN 2120-AA64


Airworthiness Directives; The Boeing Company Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: We propose to revise an existing airworthiness directive (AD) 
that applies to all The Boeing Company Model 737-100, -200, -200C, -
300, -400, and -500 series airplanes. The existing AD requires 
repetitive inspections to detect cracking in the web of the aft 
pressure bulkhead at body station 1016 at the aft fastener row 
attachment to the ``Y'' chord, various inspections for discrepancies at 
the aft pressure bulkhead, and related investigative and corrective 
actions if necessary. Since we issued that AD, we have determined that 
certain inspection and repair conditions must be clarified, as well as 
certain paragraph references related to the terminating action. This 
proposed AD would clarify certain actions specified in the existing AD. 
We are proposing this AD to detect and correct fatigue cracking, which 
could result in rapid decompression of the fuselage.

DATES: We must receive comments on this proposed AD by February 25, 
2013.

ADDRESSES: You may send comments, using the procedures found in 14 CFR 
11.43 and 11.45, by any of the following methods:
     Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the instructions for submitting comments.
     Fax: 202-493-2251.
     Mail: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue SE., Washington, DC 20590.
     Hand Delivery: Deliver to Mail address above between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
    For service information identified in this proposed AD, contact 
Boeing Commercial Airplanes, Attention: Data & Services Management, 
P.O. Box 3707, MC 2H-65, Seattle, 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 proposed AD, the regulatory 
evaluation, any comments received, and other information. The street 
address for the Docket Office (phone: 800-647-5527) is in the ADDRESSES 
section. Comments will be available in the AD docket shortly after 
receipt.

FOR FURTHER INFORMATION CONTACT: Alan Pohl, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue SW., Renton, Washington 98057-3356; phone: (425) 917-
6450; fax: (425) 917-6590; email: [email protected].

SUPPLEMENTARY INFORMATION:

Comments Invited

    We invite you to send any written relevant data, views, or 
arguments about this proposed AD. Send your comments to an address 
listed under the ADDRESSES section. Include ``Docket No. FAA-2012-1316; 
Directorate Identifier 2012-NM-186-AD'' at the beginning of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of this proposed AD. We 
will consider all comments received by the closing date and may amend 
this proposed AD because of those comments.
    We will post all comments we receive, without change, to http://www.regulations.gov, including any personal information you provide. We 
will also post a report summarizing each substantive verbal contact we 
receive about this proposed AD.

Discussion

    On August 31, 2012, we issued AD 2012-18-13, Amendment 39-17190 (77 
FR 57990, September 19, 2012), for all The Boeing Company Model 737-
100, -200, -200C, -300, -400, and -500 series airplanes. (AD 2012-18-13 
superseded AD 99-08-23, Amendment 39-11132 (64 FR 19879, April 23, 
1999).) That AD requires repetitive inspections to detect cracking in 
the web of the aft pressure bulkhead at body station 1016 at the aft 
fastener row attachment to the ``Y'' chord, various inspections for 
discrepancies at the aft pressure bulkhead, and related investigative 
and corrective actions if necessary. That AD resulted from several 
reports of fatigue cracking at that location. We issued that AD to 
detect and correct such fatigue cracking, which could result in rapid 
decompression of the fuselage.

Actions Since Existing AD (77 FR 57990, September 19, 2012) Was Issued

    Since we issued AD 2012-18-13, Amendment 39-17190 (77 FR 57990, 
September 19, 2012), we have determined that a certain inspection and 
repair required by paragraph (l) of AD 2012-18-13 must be clarified.

[[Page 1773]]

Paragraph (l) of the existing AD specifies to inspect for ``incorrectly 
drilled fasteners and elongated fasteners'' (as well as for cracking 
and corrosion), and also that ``if any crack, incorrectly drilled 
fastener, elongated fastener, or corrosion is found, before further 
flight, repair the web * * * .'' However, the intent of paragraph (l) 
of AD 2012-18-13 with regard to this inspection is to inspect the 
fastener holes, not the fasteners. This also reflects the corresponding 
instructions specified in Boeing Alert Service Bulletin 737-53A1214, 
Revision 4, dated December 16, 2011 (which is the appropriate source of 
service information for accomplishing the actions required by paragraph 
(l) of AD 2012-18-13). It is not possible to inspect ``fasteners'' 
using the procedures specified in Part III of the Accomplishment 
Instructions of that service bulletin. That is, the inspection 
procedures in that service bulletin apply to ``fastener holes'' and 
cannot be used to inspect ``fasteners.'' Therefore, we have revised 
paragraph (l) of this proposed AD to specify to inspect, in part, for 
``incorrectly drilled fastener holes'' and ``elongated fastener 
holes,'' as well as to specify that ``if any crack, incorrectly drilled 
fastener hole, elongated fastener hole, or corrosion is found, before 
further flight, repair * * *.''
    In addition, we also find it necessary to revise certain paragraph 
references related to the terminating action, as specified in paragraph 
(s) of AD 2012-18-13, Amendment 39-17190 (77 FR 57990, September 19, 
2012). Paragraph (s) of AD 2012-18-13 states that accomplishing the 
requirements of paragraphs (k) through (q) of that AD terminates the 
requirements of paragraphs (g) through (j) of that AD. However, we have 
determined that it is only necessary to accomplish the requirements of 
paragraph (k) of that AD in order to terminate the requirements of 
paragraphs (g) through (j) of that AD. We have revised paragraph (s) of 
this AD accordingly.

FAA's Determination

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

Proposed AD Requirements

    This proposed AD would retain all requirements of AD 2012-18-13, 
Amendment 39-17190 (77 FR 57990, September 19, 2012). This proposed AD 
would clarify certain actions in paragraph (l) of this proposed AD, 
would revise certain paragraph references related to the terminating 
action in paragraph (s) of this proposed AD, and would add new 
paragraph (u)(5) to this proposed AD as a new provision of the 
alternative method of compliance (AMOC) paragraph to allow the 
continued use of AMOCs approved previously in accordance with AD 2012-
18-13.

Costs of Compliance

    We estimate that this proposed AD affects 566 airplanes of U.S. 
registry.
    We estimate the following costs to comply with this proposed AD:

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                                                 Cost on U.S.
              Action                    Labor cost        Parts cost      Cost per product        operators
----------------------------------------------------------------------------------------------------------------
Low frequency eddy current (LFEC)  8 work-hours x $85               $0  $680...............  $384,880
 inspection [retained action from   per hour = $680.
 AD 99-08-23, Amendment 39-11132
 (64 FR 19879, April 23, 1999)].
Detailed visual inspection         2 work-hours x $85               $0  $170...............  $96,220
 [retained action from AD           per hour = $170.
 99[dash]08[dash]23, Amendment 39-
 11132 (64 FR 19879, April 23,
 1999)].
Detailed, high frequency eddy      Up to 60 work-hours              $0  Up to $5,100 per     Up to $2,886,600
 current inspection (HFEC), and     x $85 per hour =                     inspection cycle.    per inspection
 LFEC inspections of the web at     $5,100 per                                                cycle.
 the ``Y'' chord of the bulkhead,   inspection cycle.
 the web located under the outer
 circumferential tear strap, the
 ``Z'' stiffeners at the dome
 cap, and existing repairs
 [retained actions from AD 2012-
 18-13, Amendment 39-17190 (77 FR
 57990, September 19, 2012)].
----------------------------------------------------------------------------------------------------------------

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

                                               On-Condition Costs
----------------------------------------------------------------------------------------------------------------
                                                                                                     Cost per
                    Action                                 Labor cost               Parts cost        product
----------------------------------------------------------------------------------------------------------------
Detailed and HFEC inspections for oil-canning.  1 work-hour x $85 per hour = $85              $0             $85
LFEC or HFEC inspection for cracking..........  2 work-hours x $85 per hour =                 $0            $170
                                                 $170.
----------------------------------------------------------------------------------------------------------------

    We have received no definitive data that would enable us to provide 
cost estimates for the crack repairs specified in this proposed AD.

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.

[[Page 1774]]

    We are issuing this rulemaking under the authority described in 
Subtitle VII, Part A, Subpart III, Section 44701, ``General 
requirements.'' Under that section, Congress charges the FAA with 
promoting safe flight of civil aircraft in air commerce by prescribing 
regulations for practices, methods, and procedures the Administrator 
finds necessary for safety in air commerce. This regulation is within 
the scope of that authority because it addresses an unsafe condition 
that is likely to exist or develop on products identified in this 
rulemaking action.

Regulatory Findings

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

List of Subjects in 14 CFR Part 39

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

The Proposed Amendment

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

PART 39--AIRWORTHINESS DIRECTIVES

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

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


Sec.  39.13  [Amended]

0
2. The FAA amends Sec.  39.13 by adding the following new AD:

The Boeing Company: Docket No. FAA-2012-1316; Directorate Identifier 
2012-NM-186-AD.

(a) Comments Due Date

    The FAA must receive comments on this AD action by February 25, 
2013.

(b) Affected ADs

    This AD revises AD 2012-18-13, Amendment 39-17190 (77 FR 57990, 
September 19, 2012).

(c) Applicability

    This AD applies to all The Boeing Company Model 737-100, -200, -
200C, -300, -400, and -500 series airplanes, certificated in any 
category.

(d) Subject

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

(e) Unsafe Condition

    This AD was prompted by several reports of fatigue cracks in the 
aft pressure bulkhead. We are issuing this AD to detect and correct 
such fatigue cracking, which could result in rapid decompression of 
the fuselage.

(f) Compliance

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

(g) Retained Initial Inspection

    This paragraph restates the initial inspection required by 
paragraph (g) of AD 2012-18-13, Amendment 39-17190 (77 FR 57990, 
September 19, 2012). Perform either inspection specified by 
paragraph (g)(1) or (g)(2) of this AD at the time specified in 
paragraph (h) of this AD.
    (1) Perform a low frequency eddy current (LFEC) inspection from 
the aft side of the aft pressure bulkhead to detect discrepancies 
(including cracking, misdrilled fastener holes, and corrosion) of 
the web of the upper section of the aft pressure bulkhead at body 
station 1016 at the aft fastener row attachment to the ``Y'' chord, 
from stringer 15 left (S-15L) to stringer 15 right (S-15R), in 
accordance with Boeing 737 Nondestructive Test Manual D6-37239, Part 
6, Section 53-10-54, dated December 5, 1998.
    (2) Perform a detailed visual inspection of the aft fastener row 
attachment to the ``Y'' chord from the forward side of the aft 
pressure bulkhead to detect discrepancies (including cracking, 
misdrilled fastener holes, and corrosion) of the entire web of the 
aft pressure bulkhead at body station 1016.

(h) Retained Compliance Times

    This paragraph restates the compliance times specified in 
paragraph (h) of AD 2012-18-13, Amendment 39-17190 (77 FR 57990, 
September 19, 2012). Perform the inspection required by paragraph 
(g) of this AD at the time specified in paragraph (h)(1), (h)(2), or 
(h)(3) of this AD, as applicable.
    (1) For airplanes that have accumulated 40,000 or more total 
flight cycles as of May 10, 1999 (the effective date of AD 99-08-23, 
Amendment 39-11132 (64 FR 19879, April 23, 1999)): Inspect within 
375 flight cycles or 60 days after May 10, 1999 (the effective date 
of AD 99-08-23), whichever occurs later.
    (2) For airplanes that have accumulated 25,000 or more total 
flight cycles and fewer than 40,000 total flight cycles as of May 
10, 1999 (the effective date of AD 99-08-23, Amendment 39-11132 (64 
FR 19879, April 23, 1999)): Inspect within 750 flight cycles or 90 
days after May 10, 1999 (the effective date of AD 99-08-23), 
whichever occurs later.
    (3) For airplanes that have accumulated fewer than 25,000 total 
flight cycles as of May 10, 1999 (the effective date of AD 99-08-23, 
Amendment 39-11132 (64 FR 19879, April 23, 1999)): Inspect prior to 
the accumulation of 25,750 total flight cycles.

(i) Retained Repetitive Inspections

    This paragraph restates the repetitive inspections required by 
paragraph (i) of AD 2012-18-13, Amendment 39-17190 (77 FR 57990, 
September 19, 2012). Within 1,200 flight cycles after performing the 
initial inspection required by paragraph (g) of this AD, and 
thereafter at intervals not to exceed 1,200 flight cycles: Perform 
either inspection specified by paragraph (g)(1) or (g)(2) of this 
AD.

(j) Retained Corrective Actions

    This paragraph restates the corrective actions required by 
paragraph (j) of AD 2012-18-13, Amendment 39-17190 (77 FR 57990, 
September 19, 2012). If any discrepancy is detected during any 
inspection required by paragraph (g), (h), or (i) of this AD: Prior 
to further flight, accomplish the actions specified by paragraphs 
(j)(1) and (j)(3) of this AD, and paragraph (j)(2) of this AD, if 
applicable.
    (1) Perform a high frequency eddy current inspection from the 
forward side of the bulkhead to detect cracking of the web at the 
``Y'' chord attachment, around the entire periphery of the ``Y'' 
chord, in accordance with Boeing 737 Nondestructive Test Manual D6-
37239, Part 6, Section 51-00-00, Figure 23, dated November 5, 1995.
    (2) If the most recent inspection performed in accordance with 
paragraph (g) of this AD was not a detailed visual inspection: 
Accomplish the actions specified by paragraph (g)(2) of this AD. If 
the inspection was a detailed visual inspection, it is not necessary 
to repeat that inspection prior to further flight.
    (3) Repair any discrepancy such as cracking or corrosion or 
misdrilled fastener holes using a method approved in accordance with 
the procedures specified in paragraph (u) of this AD.

(k) Retained Inspections of the Web at the ``Y'' Chord Upper Bulkhead 
From S-15L to S-15R

    This paragraph restates the inspections of the web at the ``Y'' 
chord upper bulkhead from S-15L to S-15R required by paragraph (k) 
of AD 2012-18-13, Amendment 39-17190 (77 FR 57990, September 19, 
2012). At the later of the times specified in paragraphs (k)(1) and 
(k)(2) of this AD: Do detailed and LFEC inspections of the aft side 
of the bulkhead web, or do detailed and high frequency eddy current 
(HFEC) inspections from the forward side of the bulkhead, and do all 
applicable related investigative and corrective actions; in 
accordance with Part 1 of the Accomplishment Instructions of Boeing 
Alert Service Bulletin 737-53A1214, Revision 4, dated December 16, 
2011, except

[[Page 1775]]

as required by paragraphs (r)(1) and (r)(3) of this AD. Inspect for 
cracks, incorrectly drilled fastener holes, and elongated fastener 
holes. Do all applicable related investigative and corrective 
actions before further flight. Repeat the inspections at the 
applicable times specified in table 1 of paragraph 1.E., 
``Compliance,'' of Boeing Alert Service Bulletin 737-53A1214, 
Revision 4, dated December 16, 2011.
    (1) Prior to the accumulation of 25,000 total flight cycles.
    (2) Except as required by paragraphs (r)(2) and (r)(4) of this 
AD, at the later of the times specified in the ``Compliance Time'' 
column in table 1 of paragraph 1.E., ``Compliance,'' of Boeing Alert 
Service Bulletin 737-53A1214, Revision 4, dated December 16, 2011.

(l) Retained Inspections of the Web at the ``Y'' Chord in the Lower 
Bulkhead From S-15L to S-15R With Revised Inspection and Repair 
Conditions

    This paragraph restates the inspections of the web at the ``Y'' 
chord in the lower bulkhead from S-15L to S-15R required by 
paragraph (l) of AD 2012-18-13, Amendment 39-17190 (77 FR 57990, 
September 19, 2012), with revised inspection and repair conditions. 
Except as required by paragraphs (r)(2) and (r)(5) of this AD, at 
the applicable time specified in table 2 of paragraph 1.E., 
``Compliance,'' of Boeing Alert Service Bulletin 737-53A1214, 
Revision 4, dated December 16, 2011: Do detailed and eddy current 
inspections of the web from the forward or aft side of the bulkhead 
for cracks, incorrectly drilled fastener holes, and elongated 
fastener holes, in accordance with Part III of the Accomplishment 
Instructions of Boeing Alert Service Bulletin 737-53A1214, Revision 
4, dated December 16, 2011, except as required by paragraphs (r)(1) 
and (r)(3) of this AD. If any crack, incorrectly drilled fastener 
hole, elongated fastener hole, or corrosion is found, before further 
flight, repair using a method approved in accordance with the 
procedures specified in paragraph (u) of this AD. Repeat the 
inspections at the applicable times specified in table 2 of 
paragraph 1.E., ``Compliance,'' of Boeing Alert Service Bulletin 
737-53A1214, Revision 4, dated December 16, 2011.

(m) Retained One-Time Inspection Under the Tear Strap

    This paragraph restates the one-time inspection under the tear 
strap required by paragraph (m) of AD 2012-18-13, Amendment 39-17190 
(77 FR 57990, September 19, 2012). Except as required by paragraphs 
(r)(2) and (r)(5) of this AD, at the applicable time specified in 
table 3 of paragraph 1.E., ``Compliance,'' of Boeing Alert Service 
Bulletin 737-53A1214, Revision 4, dated December 16, 2011: Do a one-
time LFEC inspection for cracks on the aft side of the bulkhead of 
the web located under the outer circumferential tear strap, or do a 
one-time HFEC inspection for cracks from the forward side of the 
bulkhead of the web located under the outer circumferential tear 
strap, in accordance with Part II of the Accomplishment Instructions 
of Boeing Alert Service Bulletin 737-53A1214, Revision 4, dated 
December 16, 2011, except as required by paragraph (r)(1) of this 
AD. If any cracking is found, before further flight, repair the 
bulkhead using a method approved in accordance with the procedures 
specified in paragraph (u) of this AD.

(n) Retained Inspection for Oil-Canning

    This paragraph restates the inspection for oil-canning required 
by paragraph (n) of AD 2012-18-13, Amendment 39-17190 (77 FR 57990, 
September 19, 2012). Except as required by paragraph (r)(2) of this 
AD, at the applicable time specified in table 4 of paragraph 1.E., 
``Compliance,'' of Boeing Alert Service Bulletin 737-53A1214, 
Revision 4, dated December 16, 2011: Do a detailed inspection from 
the aft side of the bulkhead for oil-canning and do all applicable 
related investigative and corrective actions, in accordance with 
Part II of the Accomplishment Instructions of Boeing Alert Service 
Bulletin 737-53A1214, Revision 4, dated December 16, 2011, except as 
required by paragraph (r)(1) of this AD. Do all related 
investigative and corrective actions before further flight. 
Thereafter, repeat the inspection at the applicable times specified 
in table 4 of paragraph 1.E., ``Compliance,'' of Boeing Alert 
Service Bulletin 737-53A1214, Revision 4, dated December 16, 2011. 
For oil-cans found within the limits specified in Part II of the 
Accomplishment Instructions of Boeing Alert Service Bulletin 737-
53A1214, Revision 4, dated December 16, 2011: In lieu of installing 
the repair before further flight, at the applicable times specified 
in table 4 of paragraph 1.E., ``Compliance,'' of Boeing Alert 
Service Bulletin 737-53A1214, Revision 4, dated December 16, 2011, 
do initial and repetitive detailed and HFEC inspections for cracks 
of the oil-canning and install the repair, in accordance with the 
Accomplishment Instructions of Boeing Alert Service Bulletin 737-
53A1214, Revision 4, dated December 16, 2011. If any crack is found, 
before further flight, repair the cracking using a method approved 
in accordance with the procedures specified in paragraph (u) of this 
AD. Installing the repair terminates the repetitive inspections for 
cracks.

(o) Retained Inspection of the Dome Cap at the Center of the Bulkhead

    This paragraph restates the inspection of the dome cap at the 
center of the bulkhead required by paragraph (o) of AD 2012-18-13, 
Amendment 39-17190 (77 FR 57990, September 19, 2012). Except as 
required by paragraphs (r)(2) and (r)(5) of this AD, at the 
applicable time specified in table 5 of paragraph 1.E., 
``Compliance,'' of Boeing Alert Service Bulletin 737-53A1214, 
Revision 4, dated December 16, 2011: Do an eddy current inspection 
to detect any cracking of the dome cap at the center of the 
bulkhead, and do all applicable corrective actions, in accordance 
with Part IV of the Accomplishment Instructions of Boeing Alert 
Service Bulletin 737-53A1214, Revision 4, dated December 16, 2011. 
Do all corrective actions before further flight. Repeat the 
inspection at the times specified in table 5 of paragraph 1.E., 
``Compliance,'' of Boeing Alert Service Bulletin 737-53A1214, 
Revision 4, dated December 16, 2011.

(p) Retained Inspection of the Forward Flange of the ``Z'' Stiffeners 
at the Dome Cap

    This paragraph restates the inspection of the forward flange of 
the ``Z'' stiffeners at the dome cap required by paragraph (p) of AD 
2012-18-13, Amendment 39-17190 (77 FR 57990, September 19, 2012). 
Except as required by paragraphs (r)(2) and (r)(5) of this AD, at 
the applicable time specified in table 6 of paragraph 1.E., 
``Compliance,'' of Boeing Alert Service Bulletin 737-53A1214, 
Revision 4, dated December 16, 2011: Do an HFEC inspection to detect 
any cracking of the ``Z'' stiffener flanges at the dome cap in the 
center of the bulkhead, in accordance with Part V of the 
Accomplishment Instructions of Boeing Alert Service Bulletin 737-
53A1214, Revision 4, dated December 16, 2011, except as required by 
paragraph (r)(1) of this AD. If any crack is found, before further 
flight, repair the flanges using a method approved in accordance 
with the procedures specified in paragraph (u) of this AD. Repeat 
the inspection at the applicable times specified in table 6 of 
paragraph 1.E., ``Compliance,'' of Boeing Alert Service Bulletin 
737-53A1214, Revision 4, dated December 16, 2011.

(q) Retained Inspection for Existing Repairs on the Bulkhead

    This paragraph restates the inspection for existing repairs on 
the bulkhead required by paragraph (q) of AD 2012-18-13, Amendment 
39-17190 (77 FR 57990, September 19, 2012). Except as required by 
paragraph (r)(2) of this AD, at the applicable time specified in 
table 7 of paragraph 1.E., ``Compliance,'' of Boeing Alert Service 
Bulletin 737-53A1214, Revision 4, dated December 16, 2011: Do a 
detailed inspection of the bulkhead web and stiffeners for existing 
repairs, in accordance with Part VI of the Accomplishment 
Instructions of Boeing Alert Service Bulletin 737-53A1214, Revision 
4, dated December 16, 2011, except as required by paragraph (r)(1) 
of this AD.
    (1) If any repair identified in the ``Condition'' column of 
table 8 of paragraph 1.E., ``Compliance,'' of Boeing Alert Service 
Bulletin 737-53A1214, Revision 4, dated December 16, 2011, is found 
and the ``Reference'' column refers to Appendix A, B, C, or D of 
that service bulletin: At the applicable times specified in table 8 
of paragraph 1.E., ``Compliance,'' of Boeing Alert Service Bulletin 
737-53A1214, Revision 4, dated December 16, 2011, except as required 
by paragraph (r)(2) of this AD, do an HFEC inspection or an LFEC 
inspection of the web for cracking, in accordance with Appendix A, 
B, C, or D, as applicable, of Boeing Alert Service Bulletin 737-
53A1214, Revision 4, dated December 16, 2011. If any cracking is 
found, before further flight, repair using a method approved in 
accordance with the procedures specified in paragraph (u) of this 
AD. Repeat the inspections thereafter at the applicable intervals 
specified in table 8 of paragraph 1.E., ``Compliance,'' of Boeing 
Alert Service Bulletin 737-53A1214, Revision 4, dated December 16, 
2011.

[[Page 1776]]

    (2) If any repair identified in the ``Condition'' column of 
table 8 of paragraph 1.E., ``Compliance,'' of Boeing Alert Service 
Bulletin 737-53A1214, Revision 4, dated December 16, 2011, is found 
and the ``Reference'' column refers to Appendix E of that service 
bulletin: At the applicable times specified in table 8 of paragraph 
1.E., ``Compliance,'' of Boeing Alert Service Bulletin 737-53A1214, 
Revision 4, dated December 16, 2011, except as required by paragraph 
(r)(2) of this AD, remove the repair and replace with a new repair, 
in accordance with Appendix E of Boeing Alert Service Bulletin 737-
53A1214, Revision 4, dated December 16, 2011.
    (3) If any non-SRM (structural repair manual) repair is found 
and the repair does not have FAA-approved damage tolerance 
inspections, except as required by paragraph (r)(2) of this AD, at 
the applicable time specified in table 7 of Paragraph 1.E., 
``Compliance,'' of Boeing Alert Service Bulletin 737-53A1214, 
Revision 4, dated December 16, 2011: Contact the Boeing Commercial 
Airplanes Organization Designation Authorization (ODA) that has been 
authorized by the Manager, Seattle Aircraft Certification Office, 
for damage tolerance inspections. Do those damage tolerance 
inspections at the times given using a method approved in accordance 
with the procedures specified in paragraph (u) of this AD.

(r) Retained Exceptions to the Service Information

    This paragraph restates the exceptions to the service 
information required by paragraph (r) of AD 2012-18-13, Amendment 
39-17190 (77 FR 57990, September 19, 2012).
    (1) Where Boeing Alert Service Bulletin 737-53A1214, Revision 4, 
dated December 16, 2011, specifies to contact Boeing for repair 
instructions: Before further flight, repair using a method approved 
in accordance with the procedures specified in paragraph (u) of this 
AD.
    (2) Where Boeing Alert Service Bulletin 737-53A1214, Revision 4, 
dated December 16, 2011, specifies a compliance time ``after the 
date of Revision 1 to this service bulletin,'' ``from the date of 
Revision 3 of this service bulletin,'' ``after the date of Revision 
3 to this service bulletin,'' or ``of the effective date of AD 99-
08-23,'' this AD requires compliance within the specified compliance 
time after October 24, 2012 (the effective date of AD 2012-18-13, 
Amendment 39-17190 (77 FR 57990, September 19, 2012)).
    (3) Access and restoration procedures specified in the 
Accomplishment Instructions of Boeing Alert Service Bulletin 737-
53A1214, Revision 4, dated December 16, 2011, are not required by 
this AD. Operators may do those procedures following their 
maintenance practices.
    (4) Where table 1 of paragraph 1.E., ``Compliance'' of Boeing 
Alert Service Bulletin 737-53A1214, Revision 4, dated December 16, 
2011, specifies a compliance time relative to actions done ``in 
accordance with paragraph (a)(2) of AD 99-08-23,'' this AD requires 
compliance within the specified compliance time relative to actions 
specified in paragraph (g)(2) of this AD.
    (5) Where the Condition columns in tables 2, 3, 5, and 6 of 
paragraph 1.E., ``Compliance,'' of Boeing Alert Service Bulletin 
737-53A1214, Revision 4, dated December 16, 2011, refer to total 
flight cycles, this AD applies to the airplanes with the specified 
total flight cycles as of October 24, 2012 (the effective date of AD 
2012-18-13, Amendment 39-17190 (77 FR 57990, September 19, 2012)).

(s) Retained Terminating Action With Revised Paragraph Reference

    This paragraph restates the terminating action specified in 
paragraph (s) of AD 2012-18-13, Amendment 39-17190 (77 FR 57990, 
September 19, 2012), with a revised paragraph reference. 
Accomplishment of the requirements in paragraph (k) of this AD 
terminates the requirements of paragraphs (g) through (j) of this 
AD.

(t) Credit for Previous Actions

    This paragraph restates the credit for previous actions 
specified by paragraph (t) of AD 2012-18-13, Amendment 39-17190 (77 
FR 57990, September 19, 2012). This paragraph provides credit for 
the actions required by paragraphs (k) through (s) of this AD, if 
the actions were performed before the effective date of this AD 
using the service bulletins specified in paragraphs (t)(1) through 
(t)(4) of this AD.
    (1) Boeing Alert Service Bulletin 737-53A1214, dated June 17, 
1999.
    (2) Boeing Alert Service Bulletin 737-53A1214, Revision 1, dated 
June 22, 2000.
    (3) Boeing Alert Service Bulletin 737-53A1214, Revision 2, dated 
May 24, 2001.
    (4) Boeing Alert Service Bulletin 737-53A1214, Revision 3, dated 
January 19, 2011.

(u) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, Seattle Aircraft Certification Office (ACO), 
FAA, has the authority to approve AMOCs for this AD, if requested 
using the procedures found in 14 CFR 39.19. In accordance with 14 
CFR 39.19, send your request to your principal inspector or local 
Flight Standards District Office, as appropriate. If sending 
information directly to the manager of the ACO, send it to the 
attention of the person identified in 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 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 99-08-23, 
Amendment 39-11132 (64 FR 19879, April 23, 1999), are approved as 
AMOCs for the corresponding provisions of this AD.
    (5) AMOCs approved previously in accordance with AD 2012-18-13, 
Amendment 39-17190 (77 FR 57990, September 19, 2012), are approved 
as AMOCs for the corresponding provisions of this AD.

(v) Related Information

    (1) For more information about this AD, contact Alan Pohl, 
Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft 
Certification Office, 1601 Lind Avenue SW., Renton, Washington 
98057-3356; phone: (425) 917-6440; 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.

    Issued in Renton, Washington, on January 2, 2013.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2013-00186 Filed 1-8-13; 8:45 am]
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