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[Federal Register Volume 76, Number 228 (Monday, November 28, 2011)]
[Proposed Rules]
[Pages 72858-72863]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2011-30603]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2011-1255; Directorate Identifier 2010-NM-182-AD]
RIN 2120-AA64

Airworthiness Directives; The Boeing Company Model 737-100, -200, 
-200C, -300, -400, and -500 Series Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: We propose to supersede two existing airworthiness directives 
(AD) that apply to Model 737-100, -200, -200C, -300, -400, and -500 
series airplanes. The first existing AD currently requires, for certain 
airplanes, repetitive inspections of the Station (STA) 348.2 frame to 
detect cracking under the stop fittings and intercostal flanges at 
stringers S-14L, S-15L, and S-16L, and corrective action if necessary. 
The second existing AD currently requires repetitive inspections to 
detect cracking of the intercostal webs, attachment clips, and stringer 
splice channels, and corrective action if necessary. Since we issued 
those ADs, we have received reports of cracking of the STA 348.2 frame 
above the two outboard fasteners attaching the frame inner chord and 
door stop fittings, and in the outboard chord at stringer S-16L. We 
have also received reports of missing fasteners in the STA 348.2 frame 
inner chord. This proposed AD would require additional airplanes to do 
the inspection for cracking under the stop fittings; extend the 
repetitive interval for certain airplanes; add a one-time inspection to 
detect missing fasteners; and update or add certain inspection and 
repair instructions. This proposed AD would also require, for certain 
airplanes, repetitive inspections of the cargo barrier net fitting for 
cracking and repair if necessary. This proposed AD would also add, for 
certain airplanes, repetitive inspections for cracking of the S-15L aft 
intercostal, and repair if necessary. We are proposing this AD to 
detect and correct fatigue cracking of the intercostals on the forward 
and aft sides of the forward entry door cutout, which could result in 
loss of the forward entry door and rapid decompression of the airplane.

DATES: We must receive comments on this proposed AD by January 12, 
2012.

ADDRESSES: You may send comments 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 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; email me.boecom@boeing.com; 
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: Alan.Pohl@faa.gov.

SUPPLEMENTARY INFORMATION:

[[Page 72859]]

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-2011-1255; 
Directorate Identifier 2010-NM-182-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 April 20, 2004, we issued AD 2004-09-09, Amendment 39-13598 (69 
FR 23646, April 30, 2004), for all Boeing Model 737-200C series 
airplanes. That AD requires repetitive inspections of the Station (STA) 
348.2 frame to detect cracking under the stop fittings and intercostal 
flanges at Stringers S-14L, S-15L, and S-16L; and corrective action if 
necessary. That AD resulted from a report of cracks in the STA 348.2 
frame on a Boeing Model 737-200C series airplane. We issued that AD to 
detect and correct fatigue cracking of the intercostals on the forward 
and aft sides of the forward entry door cutout, which could result in 
the loss of the forward entry door and rapid decompression of the 
airplane.
    On July 23, 2009, we issued AD 2009-16-14, Amendment 39-15987 (74 
FR 38901, August 5, 2009), for certain Boeing Model 737-100, -200, -
200C, -300, -400, and -500 series airplanes. That AD requires 
repetitive inspections of the intercostal webs, attachment clips, and 
stringer splice channels for cracks; and corrective action if 
necessary. That AD resulted from reports of fatigue cracks on several 
Boeing Model 737-200 series airplanes. We issued that AD to detect and 
correct fatigue cracking of the intercostals on the forward and aft 
sides of the forward entry door, which could result in loss of the 
forward entry door and rapid decompression of the airplane.

Actions Since Existing ADs Were Issued

    Since we issued AD 2004-09-09, Amendment 39-13598 (69 FR 23646, 
April 30, 2004), we have received reports of cracking above the two 
outboard fasteners attaching the frame inner chord and door stop 
fitting of the STA 348.2 frame at S-15L. The cracking was reported on 
seven airplanes that had accumulated between 19,185 and 64,800 flight 
cycles (AD 2004-09-09 applies only to Model 737-200C airplanes). 
Cracking has also been found in the outboard chord at S-16L. In 
addition, we have received reports of 10 airplanes with missing 
fasteners in the STA 348.2 frame inner chord at S-7L through S-15L.
    In addition, the requirement to inspect the intercostal on the aft 
side at S-14L to S-16L is common to both AD 2004-09-09, Amendment 39-
13598 (69 FR 23646, April 30, 2004), and AD 2009-16-14, Amendment 39-
15987 (74 FR 38901, August 5, 2009). Service history indicates that the 
repetitive inspection interval of 6,000 flight cycles for that area, as 
required by AD 2009-16-14, Amendment 39-15987 (74 FR 38901, August 5, 
2009), is adequate to ensure continued operational safety. The 
repetitive interval required by AD 2004-09-09, Amendment 39-13598 (69 
FR 23646, April 30, 2004), is 4,500 flight cycles.
    Boeing Commercial Airplanes has received a Organization Designation 
Authorization (ODA). We have revised paragraph (h) of this proposed AD 
to delegate the authority to approve an alternative method of 
compliance for any repair required by this AD to the Boeing Commercial 
Airplanes ODA rather than a Designated Engineering Representative 
(DER).

Relevant Service Information

    We reviewed Boeing Alert Service Bulletin 737-53A1204, Revision 2, 
dated June 24, 2010. The procedures in Boeing Alert Service Bulletin 
737-53A1204, Revision 2, dated June 24, 2010, differ from those in 737-
53A1204, Revision 1, dated March 26, 2007 (the appropriate source of 
service information for AD 2009-16-14 (74 FR 38901, August 5, 2009)), 
as follows:
     Repetitive detailed and high frequency eddy current (HFEC) 
inspections for cracking of the S-15L aft intercostal between body 
station (BS) 348.2 and BS 360 and a detailed inspection of the cargo 
barrier net fitting at the intercostal are added for Model 737-200C 
airplanes.
     New repair instructions are added for cracking found at 
the S-14L, S-15L, and S-16L intercostals. The repair includes either 
doing actions specified in Boeing Alert Service Bulletin 737-53A1240, 
Revision 1, dated June 29, 2010 (described below), or, if a crack is at 
the S-15L aft intercostal or the damage at other intercostal locations 
is outside certain parameters covered in Boeing Alert Service Bulletin 
737-53A1240, Revision 1, Boeing Alert Service Bulletin 737-53A1204, 
Revision 2, dated June 24, 2010, specifies contacting Boeing for repair 
instructions.
    We also reviewed Boeing Alert Service Bulletin 737-53A1240, 
Revision 1, dated June 29, 2010. The procedures in Boeing Alert Service 
Bulletin 737-53A1240, Revision 1, dated June 29, 2010, differ from 
those in Boeing Alert Service Bulletin 737-53A1240, dated April 10, 
2003 (the appropriate source of service information for AD 2004-09-09, 
Amendment 39-13598 (69 FR 23646, April 30, 2004)), as follows:
     All Model 737-100, -200, -300, -400, and -500 series 
airplanes (i.e., line numbers 1 through 3132) are added to the 
effectivity. For these airplanes, the service bulletin specifies 
procedures for inspecting under the stop fitting by doing HFEC and 
surface eddy current inspections for cracking of the frame, HFEC 
inspections for cracking of the reinforcement angle and shear web, and 
doing a detailed inspection for cracking of the STA 348.2 frame outer 
chord, inner chord, and reinforcement angle, and corrective actions if 
necessary. The corrective actions include replacing certain cracked 
parts with new parts, and if a crack is found in the frame outer chord, 
contacting Boeing for repair instructions and doing the repair.
     For Model 737-200C airplanes, the repetitive interval for 
the HFEC inspection of the STA 348.2 frame is extended from 4,500 
flight cycles to 6,000 flight cycles.
     For Model 737-100, -200, -300, -400, and -500 series 
airplanes, a one-time detailed inspection is added to detect missing 
fasteners of the STA 348.2 frame inner chord at S-7L through S-15L. If 
any fastener is missing, the service bulletin specifies to contact 
Boeing for repair instructions.
     For all airplanes, intercostal inspections for cracking 
between STA 348.2 and STA 360 are now specified in Boeing Alert Service 
Bulletin 737-53A1204, Revision 2, dated June 24, 2010. Previously, for 
the intercostals at S-14 through S-16L, this inspection was common to 
both Boeing Alert Service Bulletin 737-53A1204 and Boeing Alert Service 
Bulletin 737-53A1240 for Model 737-200C airplanes.
     For Group 3 airplanes, instructions are added for repair 
of the STA 348.2 frame inner chord, reinforcement angle, and shear web; 
and of the door stop intercostals at S-14L through S16L.

[[Page 72860]]

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 certain requirements of AD 2004-09-
09, Amendment 39-13598 (69 FR 23646, April 30, 2004) and AD 2009-16-14, 
Amendment 39-15987 (74 FR 38901, August 5, 2009). This proposed AD 
would add airplanes to the applicability for the HFEC inspection for 
cracking of the stop fittings at the shear web at STA 348.2 frame; 
extend the repetitive interval for the HFEC inspection of the STA 348.2 
frame for Model 737-200C airplanes; add an inspection to detect missing 
fasteners of the STA 348.2 frame inner chord; and update or add certain 
inspection and repair instructions. This proposed AD would also require 
accomplishing the actions specified in the service information 
described previously.''

Changes to Existing ADs

    Since those ADs were issued, the AD format has been revised, and 
certain paragraphs have been rearranged. As a result, the corresponding 
paragraph identifiers have changed in this proposed AD, as listed in 
the following tables:

                      Revised Paragraph Identifiers
------------------------------------------------------------------------
   Requirement in AD 2004-09-09,
  Amendment 39-13598 (69 FR 23646,    Corresponding requirement in this
          April 30, 2004)                        proposed AD
------------------------------------------------------------------------
             paragraph (a)                        paragraph (g)
             paragraph (b)                        paragraph (h)
------------------------------------------------------------------------

------------------------------------------------------------------------
   Requirement in AD 2009-16-14,
  Amendment 39-15987 (74 FR 38901,    Corresponding requirement in this
          August 5, 2009)                        proposed AD
------------------------------------------------------------------------
             paragraph (f)                        paragraph (i)
             paragraph (g)                        paragraph (j)
             paragraph (h)                        paragraph (k)
             paragraph (i)                        paragraph (l)
             paragraph (j)                        paragraph (m)
             paragraph (k)                        paragraph (n)
             paragraph (l)                        paragraph (o)
------------------------------------------------------------------------

Costs of Compliance

    We estimate that this proposed AD affects 581 airplanes of U.S. 
registry.
    We estimate the following costs to comply with this proposed AD:

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                             Parts                              Cost on U.S.
              Action                      Labor cost          cost      Cost per product          operators
----------------------------------------------------------------------------------------------------------------
Inspections for cracking under the  18 work-hours x $85           $0  $1,530 [per           $888,930 [per
 stop fittings and intercostal       per hour = $1,530                 inspection cycle].    inspection cycle].
 flanges [retained from AD 2004-09-  [per inspection
 09, Amendment 39[dash]13598 (69     cycle].
 FR 23646, April 30, 2004)].
Inspection of areas forward of the  2 work-hours x $85            $0  $170 [per inspection  $98,770 [per
 aft entry door [retained from AD    per hour = $170 [per              cycle].               inspection cycle].
 2009-16-14, Amendment 39-15987      inspection cycle].
 (74 FR 38901, August 5, 2009)].
Inspection of areas aft of the      1 work-hour x $85 per         $0  $85 [per inspection   $49,385 [per
 forward entry door [retained from   hour = $85 [per                   cycle].               inspection cycle].
 AD 2009-16-14, Amendment 39-15987   inspection cycle].
 (74 FR 38901, August 5, 2009)].
Inspection for missing fasteners    1 work-hour x $85 per       $476  $561................  $325,941.
 [new proposed action].              hour = $85.
----------------------------------------------------------------------------------------------------------------

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

                                               On-Condition Costs
----------------------------------------------------------------------------------------------------------------
               Action                       Labor cost                Parts cost            Cost per  product
----------------------------------------------------------------------------------------------------------------
Repair of cracking if done in        Unknown.................  Unknown.................  Unknown.
 accordance with a method approved
 by the FAA.
Repair of cracking if done in        24 work-hours...........  $11,856.................  $13,896.
 accordance with Boeing Alert
 Service Bulletin 737-53A1240.
----------------------------------------------------------------------------------------------------------------

    According to the manufacturer, some of the costs of this proposed 
AD may be covered under warranty, thereby reducing the cost impact on 
affected individuals. We do not control warranty coverage for affected 
individuals. As a result, we have included all costs in our cost 
estimate.

Authority for This Rulemaking

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

Regulatory Findings

    We have determined that this proposed AD would not have federalism 
implications under Executive Order 13132. This proposed AD would not 
have a substantial direct effect on the States, on the relationship 
between the national Government and the States, or on the distribution 
of power and responsibilities among the various levels of government.

[[Page 72861]]

    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

    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]

    2. The FAA amends Sec.  39.13 by removing airworthiness directive 
(AD) 2004-09-09, Amendment 39-13598 (69 FR 23646, April 30, 2004), and 
AD 2009-16-14, Amendment 39-15987 (74 FR 38901, August 5, 2009), and 
adding the following new AD:

The Boeing Company: Docket No. FAA-2011-1255; Directorate Identifier 
2010-NM-182-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by January 
12, 2012.

Affected ADs

    (b) This AD supersedes AD 2004-09-09, Amendment 39-13598 (69 FR 
23646, April 30, 2004); and AD 2009-16-14, Amendment 39-15987 (74 FR 
38901, August 5, 2009).

Applicability

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

Subject

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

Unsafe Condition

    (e) This AD was prompted by reports of cracking of the STA 348.2 
frame above the two outboard fasteners attaching the frame inner 
chord and door stop fittings, and in the outboard chord at stringer 
S-16L. We have also received reports of missing fasteners in the STA 
348.2 frame inner chord. We are issuing this AD to detect and 
correct fatigue cracking of the intercostals on the forward and aft 
sides of the forward entry door cutout, which could result in loss 
of the forward entry door and rapid decompression of the airplane.

Compliance

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

Restatement of the Requirements of AD 2004-09-09, Amendment 39-13598 
(69 FR 23646, April 30, 2004) With Revised Service Information and 
Extended Repetitive Intervals

Initial and Repetitive Inspections at STA 348.2 for Model 737-200C 
Series Airplanes

    (g) For Model 737-200C series airplanes: Except as provided by 
paragraph (h) of this AD, prior to the accumulation of 46,000 total 
flight cycles, or within 2,250 flight cycles after June 4, 2004 (the 
effective date of AD 2004-09-09, Amendment 39-13598 (69 FR 23646, 
April 30, 2004)), whichever occurs later, do detailed and eddy 
current inspections of the STA 348.2 frame for cracking under the 
stop fittings and intercostal flanges at Stringers 14L, 15L, and 16L 
by accomplishing paragraphs 3.A. and 3.B.1. through 3.B.7. of the 
Accomplishment Instructions of Boeing Alert Service Bulletin 737-
53A1240, dated April 10, 2003, or by accomplishing Part 1 of the 
Accomplishment Instructions of Boeing Alert Service Bulletin 737-
53A1240, Revision 1, dated June 29, 2010. Do the actions in 
accordance with Boeing Alert Service Bulletin 737-53A1240, dated 
April 10, 2003; or Revision 1, dated June 29, 2010. Any applicable 
repair must be accomplished prior to further flight. Repeat the 
inspections thereafter at intervals not to exceed 6,000 flight 
cycles. As of the effective date of this AD, only Boeing Alert 
Service Bulletin 737-53A1240, Revision 1, dated June 29, 2010, may 
be used.

Corrective Action for Paragraph (g) of This AD

    (h) If any crack is found during any inspection required by 
paragraph (g) of this AD, and Boeing Alert Service Bulletin 737-
53A1240, dated April 10, 2003; or Revision 1, dated June 29, 2010; 
specifies to contact Boeing for appropriate action: Before further 
flight, repair in accordance with a method approved by the Manager, 
Seattle Aircraft Certification Office (ACO), FAA; or using a method 
approved in accordance with the procedures specified in paragraph 
(t) of this AD.

Restatement of the Requirements of AD 2009-16-14, Amendment 39-15987 
(74 FR 38901, August 5, 2009) With Revised Service Information

Initial Compliance Time

    (i) For all Model 737-100, -200, -200C, -300, -400, and -500 
series airplanes, as identified in Boeing Alert Service Bulletin 
737-53A1204, Revision 1, dated March 26, 2007: Before the 
accumulation of 15,000 total flight cycles, or within 4,500 flight 
cycles after November 1, 2005 (the effective date of AD 2005-20-03, 
Amendment 39-14296 (70 FR 56361, September 27, 2005)), whichever 
occurs later: Do the inspections required by paragraphs (k) and (l) 
of this AD.
    (j) For all Model 737-200C series airplanes, as identified in 
Boeing Alert Service Bulletin 737-53A1204, Revision 1, dated March 
26, 2007: Before the accumulation of 15,000 total flight cycles, or 
within 4,500 flight cycles after September 9, 2009 (the effective 
date of AD 2009-16-14, Amendment 39-15987 (74 FR 38901, August 5, 
2009)), whichever occurs later, do the inspection required by 
paragraph (m) of this AD.

Initial Inspection for Group 1 Configuration Airplanes

    (k) For Group 1 airplanes identified in Boeing Alert Service 
Bulletin 737-53A1204, Revision 1, dated March 26, 2007: Perform a 
detailed inspection for cracking of the intercostal web, attachment 
clips, and stringer splice channels; and a high frequency eddy 
current (HFEC) inspection for cracking of the stringer splice 
channels located forward and aft of the forward entry door; and do 
all applicable corrective actions before further flight; in 
accordance with Parts 1 and 2 of the Work Instructions of Boeing 
Special Attention Service Bulletin 737-53-1204, dated June 19, 2003; 
or Boeing Alert Service Bulletin 737-53A1204, Revision 1, dated 
March 26, 2007; or in accordance with Parts 1, 2, 4, and 5 of the 
Work Instructions of Boeing Alert Service Bulletin 737-53A1204, 
Revision 2, dated June 24, 2010. After September 9, 2009 and until 
the effective date of this AD, Boeing Alert Service Bulletin 737-
53A1204, Revision 1, dated March 26, 2007; or Revision 2, dated June 
24, 2010; may be used. As of the effective date of this AD, only 
Boeing Alert Service Bulletin 737-53A1204, Revision 2, dated June 
24, 2010, may be used.

Initial Inspection for Cargo Configuration Airplanes (Forward of the 
Forward Entry Door)

    (l) For Group 2 cargo airplanes identified in Boeing Alert 
Service Bulletin 737-53A1204, Revision 1, dated March 26, 2007: 
Perform a detailed inspection for cracking of the intercostal webs 
and attachment clips located forward of the forward entry door, and 
do all applicable corrective actions before further flight, in 
accordance with Part 3 of the Work Instructions of Boeing Special 
Attention Service Bulletin 737-53-1204, dated June 19, 2003; or 
Boeing Alert Service Bulletin 737-53A1204, Revision 1, dated March 
26, 2007; or in accordance with Part 3 of Boeing Alert Service 
Bulletin 737-53A1204, Revision 2, dated June 24, 2010. After 
September 9, 2009 and until the effective date of this AD, Boeing 
Alert Service Bulletin 737-53A1204, Revision 1, dated March 26, 
2007; or Revision 2, dated June 24, 2010; may be used. As of the 
effective date of this AD, only Boeing Alert Service Bulletin 737-
53A1204, Revision 2, dated June 24, 2010, may be used.

[[Page 72862]]

Initial Inspection for Cargo Configuration Airplanes (Aft of the 
Forward Entry Door)

    (m) For Group 2 cargo airplanes identified in Boeing Alert 
Service Bulletin 737-53A1204, Revision 1, dated March 26, 2007: 
Perform a detailed inspection for cracking of the intercostal webs 
and attachment clips located aft of the forward entry door, and do 
all applicable corrective actions before further flight, in 
accordance with Part 4 of the Work Instructions of Boeing Alert 
Service Bulletin 737-53A1204, Revision 1, dated March 26, 2007; or 
in accordance with Part 3 of Boeing Alert Service Bulletin 737-
53A1204, Revision 2, dated June 24, 2010. As of the effective date 
of this AD, only Boeing Alert Service Bulletin 737-53A1204, Revision 
2, dated June 24, 2010, may be used.

Repeat Inspections

    (n) Repeat the inspections required by paragraphs (k), (l), and 
(m) of this AD thereafter at intervals not to exceed 6,000 flight 
cycles after the previous inspection, or within 3,000 flight cycles 
after September 9, 2009, whichever occurs later.

Exceptions to Boeing Special Attention Service Bulletin 737-53A1204

    (o) Do the actions required by paragraphs (i), (j), (k), (l), 
(m), and (n) of this AD by accomplishing all the applicable actions 
specified in the Accomplishment Instructions of Boeing Special 
Attention Service Bulletin 737-53-1204, dated June 19, 2003; Boeing 
Alert Service Bulletin 737-53A1204, Revision 1, dated March 26, 
2007; or Boeing Alert Service Bulletin 737-53A1204, Revision 2, 
dated June 24, 2010; except as provided by paragraphs (o)(1) and 
(o)(2) of this AD. After September 9, 2009, and until the effective 
date of this AD, Boeing Alert Service Bulletin 737-53A1204, Revision 
1, dated March 26, 2007; or Revision 2, dated June 24, 2010; may be 
used. As of the effective date of this AD, only Boeing Alert Service 
Bulletin 737-53A1204, Revision 2, dated June 24, 2010, may be used.
    (1) Where Boeing Special Attention Service Bulletin 737-53-1204, 
dated June 19, 2003; Boeing Alert Service Bulletin 737-53A1204, 
Revision 1, dated March 26, 2007; or Boeing Alert Service Bulletin 
737-53A1204, Revision 2, dated June 24, 2010; specifies to contact 
Boeing for repair instructions: Before further flight, repair using 
a method approved in accordance with the procedures specified in 
paragraph (t) of this AD.
    (2) Where Boeing Special Attention Service Bulletin 737-53-1204, 
dated June 19, 2003; or Boeing Alert Service Bulletin 737-53A1204, 
Revision 1, dated March 26, 2007; specifies a compliance time 
relative to the date of a service bulletin, this AD requires 
compliance relative to September 9, 2009. Where Boeing Special 
Attention Service Bulletin 737-53-1204, dated June 19, 2003; or 
Boeing Alert Service Bulletin 737-53A1204, Revision 1, dated March 
26, 2007; specifies a compliance time relative to the date of the 
initial release of the service bulletin, this AD requires compliance 
relative to November 1, 2005 (the effective date of AD 2005-20-03, 
Amendment 39-14296 (70 FR 56361, September 27, 2005)).

New Requirements of This AD

One-Time Inspection for Missing Fasteners at STA 348.2

    (p) For Groups 2 and 3 airplanes identified in Boeing Alert 
Service Bulletin 737-53A1240, Revision 1, dated June 29, 2010: 
Within 4,500 flight cycles after the effective date of this AD, do a 
detailed inspection to detect missing fasteners of the STA 348.2 
frame, in accordance with the Accomplishment Instructions of Boeing 
Alert Service Bulletin 737-53A1240, Revision 1, dated June 29, 2010, 
except as required by paragraph (r) of this AD. If any fastener is 
missing, before further flight, repair using a method approved in 
accordance with the procedures specified in paragraph (t) of this 
AD.

Initial and Repetitive Inspections at STA 348.2 for Model 737-100, -
200, -300, -400, and -500 Series Airplanes

    (q) For Groups 2 and 3 airplanes identified in Boeing Alert 
Service Bulletin 737-53A1240, Revision 1, dated June 29, 2010: 
Before the accumulation of 15,000 total flight cycles or within 
4,500 flight cycles after the effective date of this AD, do HFEC and 
surface eddy current inspections for cracking of the frame, HFEC 
inspections for cracking of the reinforcement angle and shear web, 
and a detailed inspection for cracking of the STA 348.2 frame outer 
chord, inner chord, and reinforcement angle, in accordance with the 
Accomplishment Instructions of Boeing Alert Service Bulletin 737-
53A1240, Revision 1, dated June 29, 2010, except as required by 
paragraph (r) of this AD. If any crack is found during any 
inspection required by this paragraph, before further flight, do all 
applicable corrective actions in accordance with the Accomplishment 
Instructions of Boeing Alert Service Bulletin 737-53A1240, Revision 
1, dated June 29, 2010, except as required by paragraph (r) of this 
AD, and except where that service bulletin specifies to contact 
Boeing, before further flight, repair using a method approved in 
accordance with the procedures specified in paragraph (t) of this 
AD. Repeat the inspections thereafter at intervals not to exceed 
6,000 flight cycles.

Exception to Boeing Alert Service Bulletin 737-53A1240

    (r) Where Boeing Alert Service Bulletin 737-53A1240, Revision 1, 
dated June 29, 2010, specifies that for the instructions identified 
in paragraph 3.B., Work Instructions, and the Figure(s) which give 
the recommended sequence of steps, the sequence of the steps to do 
the service bulletin can be changed; the requirements in this AD do 
not allow the sequence of the steps to be changed.

Initial and Repetitive Inspections of the S-15L Aft Intercostal and 
Cargo Barrier Net Fitting for Model 737-200C Series Airplanes

    (s) For Group 2 airplanes identified in Boeing Alert Service 
Bulletin 737-53A1204, Revision 2, dated June 24, 2010: Before the 
accumulation of 15,000 total flight cycles, or within 4,500 flight 
cycles after the effective date of this AD, whichever occurs later, 
do initial detailed and HFEC inspections for cracking of the S-15L 
aft intercostal between BS 348.2 and BS 360, and do a detailed 
inspection of the cargo barrier net fitting at the intercostal, in 
accordance with Figure 3 of the Accomplishment Instructions of 
Boeing Alert Service Bulletin 737-53A1204, Revision 2, dated June 
24, 2010. If any cracking is found, before further flight repair 
using a method approved in accordance with the procedures specified 
in paragraph (t) of this AD. Repeat the inspections at intervals not 
to exceed 6,000 flight cycles.

Alternative Methods of Compliance (AMOCs)

    (t)(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, it 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 Organization Designation Authorization 
(ODA) that has been authorized by the Manager, Seattle ACO to make 
those findings. For a repair method to be approved, the repair must 
meet the certification basis of the airplane, and the approval must 
specifically refer to this AD.
    (4) AMOCs approved for AD 2004-09-09, Amendment 39-13598 (69 FR 
23646, April 30, 2004), are approved as AMOCs for the corresponding 
requirements of this AD.
    (5) AMOCs approved for AD 2009-16-14, Amendment 39-15987 (74 FR 
38901, August 5, 2009), are approved as AMOCs for the corresponding 
requirements of this AD.

Related Information

    (u) For more information about this AD, contact Alan Pohl, 
Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle ACO, 
1601 Lind Avenue SW., Renton, Washington 98057-3356; phone (425) 
917-6450; fax (425) 917-6590; email: Alan.Pohl@faa.gov.
    (v) 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; email 
me.boecom@boeing.com; 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.

[[Page 72863]]

    Issued in Renton, Washington, on November 18, 2011.
John P. Piccola,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2011-30603 Filed 11-25-11; 8:45 am]
BILLING CODE 4910-13-P
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