Document ID: FAA-2009-1253-0006
Agency: faa
Document Type: Rule
Title: Airworthiness Directives: Boeing Co. Model 737-600, -700, -700C, -800, -900, and -900ER Series Airplanes
Posted Date: 2011-03-22T04:00Z

[Federal Register Volume 76, Number 55 (Tuesday, March 22, 2011)]
[Rules and Regulations]
[Pages 15808-15814]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2011-5301]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2009-1253; Directorate Identifier 2009-NM-080-AD; 
Amendment 39-16629; AD 2011-06-05]
RIN 2120-AA64

Airworthiness Directives; The Boeing Company Model 737-600, -700, 
-700C, -800, -900, and -900ER Series Airplanes

AGENCY: Federal Aviation Administration (FAA), Department of 
Transportation (DOT).

ACTION: Final rule.

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SUMMARY: The FAA is superseding an existing airworthiness directive 
(AD), which applies to all Model 737-600, -700, -700C, -800, -900, and 
-900ER series airplanes. That AD currently requires repetitive detailed 
inspections of the slat track downstop assemblies to verify that proper 
hardware is installed, one-time torquing of the nut and bolt, and 
corrective actions if necessary. This new AD also requires replacing 
the hardware of the downstop assembly with new hardware of the downstop 
assembly, doing a detailed inspection or a borescope inspection of the 
slat cans on each wing and the lower rail of the slat main tracks for 
debris, replacing the bolts of the aft side guide with new bolts, and 
removing any debris found in the slat can. This AD also removes 
airplanes from the applicability. This AD results from reports of parts 
coming off the main slat track downstop assemblies. We are issuing this 
AD to prevent loose or missing parts from the main slat track downstop 
assemblies from falling into the slat can and causing a puncture, which 
could result in a fuel leak and consequent fire.

DATES: This AD becomes effective April 26, 2011.
    The Director of the Federal Register approved the incorporation by 
reference of certain publications listed in the AD as of April 26, 
2011.

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; e-mail 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 AD, the regulatory evaluation, 
any comments received, and other information. The address for the 
Docket Office (telephone 800-647-5527) is the Document Management 
Facility, U.S. Department of Transportation, Docket Operations, M-30, 
West Building Ground Floor, Room W12-140,

[[Page 15809]]

1200 New Jersey Avenue, SE., Washington, DC 20590.

FOR FURTHER INFORMATION CONTACT: Nancy Marsh, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone (425) 
917-6440; fax (425) 917-6590.

SUPPLEMENTARY INFORMATION:

Discussion

    The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 
CFR part 39 to include an AD that supersedes AD 2007-18-52, Amendment 
39-15197 (72 FR 53928, September 21, 2007). The existing AD applies to 
all Model 737-600, -700, -700C, -800, -900, and -900ER series 
airplanes. That NPRM was published in the Federal Register on January 
11, 2010 (75 FR 1297). That NPRM proposed to require repetitive 
detailed inspections of the slat track downstop assemblies to verify 
that proper hardware is installed, one-time torquing of the nut and 
bolt, and corrective actions if necessary. That NPRM also proposed to 
require replacing the hardware of the downstop assembly with new 
hardware of the downstop assembly, doing a detailed inspection or a 
borescope inspection of the slat cans on each wing and the lower rail 
of the slat main tracks for debris, replacing the bolts of the aft side 
guide with new bolts, and removing any debris found in the slat can. 
That NPRM proposed to remove airplanes from the applicability of the 
existing AD.

Comments

    We provided the public the opportunity to participate in the 
development of this AD. We have considered the comments that have been 
received on the NPRM.

Request To Use Revised Service Information

    Boeing requested that the NPRM refer to Boeing Service Bulletin 
737-57A1302, Revision 1. Boeing stated that Revision 1 of this service 
bulletin will be forwarded to the FAA for approval.
    We agree with Boeing's request to refer to Boeing Service Bulletin 
737-57A1302, Revision 1, dated October 18, 2010. Revision 1 of this 
service bulletin has been published and made available to operators. 
There are no new actions in Boeing Service Bulletin 737-57A1302, 
Revision 1, dated October 18, 2010. We have revised paragraph (i) of 
this AD to add a reference to this service bulletin.

Request To Allow Optional Parts for Installation

    Air Transport Association (ATA), on behalf of its member airline 
American Airlines (AAL), expressed concern about the lack of optional 
manufacturer part numbers, and/or optional specifications concerning 
the parts specified in the NPRM. AAL stated that part 
interchangeability is allowed for airplanes with the same design that 
are not affected by the NPRM. AAL gave four examples:
     The NPRM allows only bolt part number (P/N) BACB30NR7DK12, 
but bolt P/N BACB30NR7DK12 has an optional part P/N 114A4102-19, that 
can be used on airplanes unaffected by the NPRM.
     The NPRM specifies retaining pin P/N BACP18BC03A06P only, 
but per Boeing part data, P/N MS24665-300 is fully interchangeable with 
P/N BACP18BC03A06P.
     The NPRM specifies to use lockwire P/N MS20995NC32 only, 
but for airplanes unaffected by the AD, the use of cable assembly P/N 
BACC13AT4K6 is allowed.
     Boeing Drawing 65-88700 allows the use of P/N MS20995C32 
and P/N MS20995N32 in lieu of P/N MS20995NC32.
    AAL stated that the intent of the NPRM is not to restrict parts to 
specific manufacturer part numbers when optional parts are readily 
available. AAL stated that similar airplanes unaffected by the AD with 
the same design allow for greater part equivalent/substitution options. 
AAL requested that the FAA, in an effort to assist the operator for 
compliance, include optional parts in the NPRM, or provide a global 
AMOC for acceptable substitutes per Boeing Drawing 65-88700, which is 
an acceptable specification interchangeability, or part substitution 
per Boeing Drawing D-590.
    We partially agree with AAL's request that optional parts be 
allowed for installation. The alternative lockwire part proposed by AAL 
has already been approved as an AMOC for those operators who have made 
the request to the FAA. Boeing has not requested approval of a global 
AMOC for all operators. We have revised paragraph (i) of this AD to 
specify that installation of stainless steel lockwire, P/N MS20995C32, 
is acceptable for compliance with this AD.
    We disagree with AAL regarding use of the alternative bolt and 
cotter pin. The alternative bolt was never produced and could be 
removed from the Boeing drawing system in the future. The alternative 
cotter pin proposed by AAL may require the use of special tooling for 
installation on in-service airplanes. The cotter pin specified in 
Boeing Alert Service Bulletin 737-57A1302, dated December 15, 2008; and 
Boeing Service Bulletin 737-57A1302, Revision 1, dated October 18, 
2010; requires the use of a special tool designed to facilitate the 
installation by the operators. Until an alternative cotter pin and 
tooling are validated for use in maintenance facilities (as opposed to 
the manufacturing environment), the proposed AMOC by AAL cannot be 
approved. If AAL obtains additional data to support such a request, it 
may apply for approval of an AMOC in accordance with the provisions 
specified in paragraph (j) of this AD.
    We disagree with AAL's request to approve the use of substitutions 
provided in Boeing Drawing 65-88700 or Drawing D-590. Boeing did not 
provide us with information to ensure that these parts adequately 
address the unsafe condition. In addition, Boeing has not requested 
approval of a global AMOC for all operators. However, operators may 
apply for approval of an AMOC in accordance with the provisions 
specified in paragraph (j) of this AD.

Request for AMOC Clarification for the Track Repair Requirements

    ATA, on behalf of its member airline AAL, expressed concern with 
requiring an AMOC for repair of a hole larger than 0.5005 inch in the 
slat main track as stated in the NPRM. AAL requested that the FAA 
clarify the boundaries of the AMOC track repair requirements and the 
method to identify the AMOC repaired tracks. AAL stated that the flap 
tracks are fully removable from the slat and are fully interchangeable 
with airplanes unaffected by the AD. AAL stated that the tracks do not 
have unique identifiers (i.e., no serial numbers) marked on the track. 
AAL stated that the requirement may also be interpreted as, for Boeing 
Alert Service Bulletin 737-57A1302, dated December 15, 2008, listed 
aircraft, repairs to the downstop hole (when greater than 0.5005 inch) 
of a slat main track performed at any time during the life of the part 
would require an AMOC.
    We provide the following clarifications.
    For clarification of the AMOC track repair requirements, the AD 
requires that any time the fastener hole in an affected slat can is 
oversized to greater than 0.5005 inch, the track must be replaced in 
accordance with Boeing Alert Service Bulletin 737-57A1302, dated 
December 15, 2008; Boeing Service Bulletin 737-57A1302, Revision

[[Page 15810]]

1, dated October 18, 2010; or repaired in accordance with paragraph (j) 
of this AD. AMOCs can be approved for airplanes included in the AD 
applicability. AMOCs are not applicable to airplanes outside the AD 
even if AD-related parts are rotated onto them. We have not changed the 
AD in this regard.
    For clarification, the method to identify the AMOC-repaired tracks, 
including the tracking of affected parts, is a requirement under Parts 
39, 121, and 43 of the Federal Aviation Regulations (14 CFR 39, 121, 
and 43). Under these parts, each airline may develop its own unique 
methodology to accomplish this activity per the procedures approved in 
its operation specification. We have not changed the AD in this regard.

Request for Re-Evaluation of Out-of-Spec Hole Issue

    ATA, on behalf of its member airline AAL, recommended re-evaluating 
the impact of an out-of-spec hole (hole larger than 0.5005 inch in the 
slat main track), and recommended the FAA gather additional information 
from operators concerning the out-of-spec hole issue.
    We disagree with AAL's recommendation. The proposal to provide and 
gather operator data should be proposed to the manufacturer. Once 
additional data are evaluated by technical specialists, operators may 
request approval of an AMOC in accordance with the provisions specified 
in paragraph (j) of this AD based on the new recommendation.

Request To Provide Reference in the Component Maintenance Manual (CMM)

    ATA, on behalf of its member airline AAL, expressed concern with 
the bushing repair of the slat main track in accordance with Boeing 
Alert Service Bulletin 737-57A1302, dated December 15, 2008. AAL stated 
that in an effort to ensure compliance with the NPRM, this repair may 
need to be referenced in the appropriate CMM section to provide the 
reference to the source of the repair data.
    From these statements, we infer that AAL is requesting that the 
bushing repair provided in Boeing Alert Service Bulletin 737-57A1302, 
dated December 15, 2008; and Boeing Service Bulletin 737-57A1302, 
Revision 1, dated October 18, 2010; be referenced in the appropriate 
CMM. We do not agree with this request. CMMs are not regulated by the 
FAA, and Boeing does not provide us with information to ensure that 
these documents remain unchanged and thus adequately address the unsafe 
condition. We have not changed the AD in this regard.

Request That the AD Clarify and Highlight Only Specific Sections of the 
Service Bulletin Affected by the AD

    ATA, on behalf of its member airline AAL, expressed concern 
regarding the requirements in Boeing Alert Service Bulletin 737-
57A1302, dated December 15, 2008, as proposed in the NPRM. AAL stated 
that the NPRM may be misinterpreted in that ``all steps'' of that 
service bulletin must be complied with. AAL requested that the AD be 
clarified and highlighted to explain only those specific sections of 
that service bulletin that are affected by the NPRM.
    AAL stated that panel open/close procedures and access procedures 
(slat extension/retraction) should not affect the compliance with the 
NPRM. AAL also stated that the actuator disconnection/reconnection and 
slat removal/installation also should not affect compliance with the 
NPRM. AAL stated that clarification may be made with the following 
statement: ``Only the service bulletin procedures specified by the AD 
are affected by the AD. Other procedures described by the service 
bulletin not specified by the AD are not affected by FAA AD compliance 
requirements.''
    We partially agree with AAL's request to clarify and highlight only 
specific sections of Boeing Alert Service Bulletin 737-57A1302, dated 
December 15, 2008; and Boeing Service Bulletin 737-57A1302, Revision 1, 
dated October 18, 2010; that are affected by the AD. For clarification, 
the manufacturer revises service bulletins, not the FAA. When the words 
``refer to'' are used in Boeing Alert Service Bulletin 737-57A1302, 
dated December 15, 2008; or Boeing Service Bulletin 737-57A1302, 
Revision 1, dated October 18, 2010; and the operator has an accepted 
alternative procedure, the accepted alternative procedure may be used. 
However, we have changed paragraph (i) of this AD to delete reference 
to the access and close sections of the Accomplishment Instructions of 
Boeing Alert Service Bulletin 737-57A1302, dated December 15, 2008; 
this AD now requires that the actions be accomplished in accordance 
with Part 2 of the Accomplishment Instructions of Boeing Alert Service 
Bulletin 737-57A1302, dated December 15, 2008; or Boeing Service 
Bulletin 737-57A1302, Revision 1, dated October 18, 2010.

Request To Provide a Global AMOC

    ATA, on behalf of its member airline AAL, stated that Boeing issued 
Service Bulletin Information Notice (IN) 737-57A1302 IN 01, dated 
February 25, 2009, to Boeing Alert Service Bulletin 737-57A1302, dated 
December 15, 2008. AAL stated that Boeing Service Bulletin IN 737-
57A1302 IN 01 provides additional instructions to install the guide 
bolts and reassemble the track downstop hole. AAL stated that Boeing 
Service Bulletin IN 737-57A1302 IN 01 also provides additional 
instructions for access and panel reinstallation. AAL requested that 
Boeing Service Bulletin IN 737-57A1302 IN 01 be approved as a global 
AMOC, or be incorporated as an option into the AD requirements to allow 
the operator to use the best practices to accomplish the job.
    We do not agree with this request. We note that a global AMOC 
already has been approved under FAA Letter 120S-09-528, dated September 
16, 2009, for Boeing Service Bulletin IN 737-57A1302 IN 01, dated 
February 25, 2009, and paragraph (i) of this AD has been revised to 
include reference to Boeing Service Bulletin 737-57A1302, Revision 1, 
dated October 18, 2010, which includes the information provided in that 
information notice. AAL may request a copy of this global AMOC from 
Boeing.

Request for Validation of the Service Bulletin Instructions To Be 
Accomplished

    ATA, on behalf of its member airline AAL, expressed concern that a 
validation program was not performed on Boeing Alert Service Bulletin 
737-57A1302, dated December 15, 2008, to ensure that data, 
instructions, and processes specified in that service bulletin are 
correct, clear, appropriate, and understood by maintenance personnel 
performing the work.
    From this statement we infer that AAL is requesting that validation 
of the instructions in Boeing Alert Service Bulletin 737-57A1302, dated 
December 15, 2008, be accomplished. We partially agree with AAL's 
request. We have confirmed that validation of Boeing Alert Service 
Bulletin 737-57A1302, dated December 15, 2008, was completed in 
December 2009. Operators may obtain further details of the validation 
from Boeing. We have not changed the AD in this regard.

Request To Revise Service Information To Include Steps To Re-Install 
Slat Can Assembly and Access Panels (If Removed)

    ATA, on behalf of its member airline AAL, stated that there are no 
steps in Boeing Alert Service Bulletin 737-57A1302, dated December 15, 
2008, to install the slat can, if removed, in

[[Page 15811]]

accordance with Part 2 of the Accomplishment Instructions of Boeing 
Alert Service Bulletin 737-57A1302, dated December 15, 2008. AAL 
requested that to ensure compliance with the AD, a step, ``If removed, 
install slat, refer to AMM 27-81-21,'' be included in Boeing Alert 
Service Bulletin 737-57A1302, dated December 15, 2008, in the 
appropriate location.
    AAL also stated that there is no procedure referenced in Boeing 
Alert Service Bulletin 737-57A1302, dated December 15, 2008, to 
reinstall the access panels removed from the lower leading edge of the 
wing. AAL stated that to ensure compliance with the AD, a step, 
``reinstall the panels that were removed from the lower leading edge of 
the wing, refer to AMM 27-81-21,'' be included in Boeing Alert Service 
Bulletin 737-57A1302, dated December 15, 2008, in the appropriate 
location.
    We disagree with AAL's request. For clarification, the 
manufacturer, not the FAA, revises service bulletins. Part 3.B.3.b. of 
the Accomplishment Instructions of Boeing Alert Service Bulletin 737-
57A1302, dated December 15, 2008; and Boeing Service Bulletin 737-
57A1302, Revision 1, dated October 18, 2010; specify that the airplane 
be returned ``to a serviceable condition,'' and accomplishment of this 
step would require reinstallation of any components that were removed 
from the airplane. When the words ``refer to'' are used in Boeing Alert 
Service Bulletin 737-57A1302, dated December 15, 2008; and Boeing 
Service Bulletin 737-57A1302, Revision 1, dated October 18, 2010; and 
the operator has an accepted alternative procedure, the accepted 
alternative procedure can be used to accomplish reinstalling the slat 
can assembly and access panels. Boeing Service Bulletin 737-57A1302, 
Revision 1, dated October 18, 2010, does include new phrasing similar 
to that requested by AAL. We have not changed this AD in this regard.

Request for an Optional Requirement to the AD

    ATA, on behalf of its member airline AAL, expressed concern with 
the measurement requirements of the slat track hole diameter. AAL 
requested that Boeing and/or the FAA provide an optional requirement to 
this AD, or a global AMOC, to allow use of a ``no-go'' type gauge or 
similar device and the associated procedure to establish hole size. AAL 
also requested providing an additional (initial) procedure consistent 
with using common maintenance measurement tools to better allow the 
operator to comply with these requirements. AAL stated that Boeing 
Alert Service Bulletin 737-57A1302, dated December 15, 2008, states 
that if the bolt has side-to-side play in the hole, then measure the 
hole. AAL stated that the allowable measurement is four decimal places 
of accuracy (0.XXXX). AAL stated that this dimension is in Boeing 
Assembly Drawing 114A7511 specification for the purpose of 
manufacturing the part in a machine shop setting. AAL also stated that 
since this task is intended to be accomplished on wing, or slat removed 
(on bench) in a dock maintenance setting, it is not practical and may 
not be feasible to require measurement within four decimal places. AAL 
stated that the methods to machine to four decimal place accuracy are 
different from the requirement to measure to four decimal place 
accuracy. AAL stated that typical tools used in a maintenance setting 
would be a ball/T gauge, micrometer, and a vernier caliper in certain 
situations (hole not near minimum/maximum limits). AAL also stated that 
using these tools on the wing could result in inaccuracy due to the 
difficulty of the measuring location and the access to the location.
    We disagree with AAL's requests to provide an optional requirement 
to this AD or a global AMOC to allow the use of a ``no-go'' type gauge 
or similar device and the associated procedure to establish hole size. 
We also disagree with AAL to add a procedure using common maintenance 
measurement tools.
    Boeing Alert Service Bulletin 737-57A1302, dated December 15, 2008; 
Boeing Service Bulletin 737-57A1302, Revision 1, dated October 18, 
2010; nor this AD; specify which tools are to be used to measure the 
hole size. In the absence of specific instructions on how to perform a 
maintenance task, operators have the discretion of developing their own 
procedures to enable their maintenance personnel to meet the 
requirements of this AD. In addition, it is the intent of this AD that 
the operators develop their own procedures to perform a routine 
maintenance task, such as drilling the close ream hole. Operators are 
referred to the manufacturer's maintenance procedures, which are 
published in formats such as the structural repair manual, the standard 
overhaul practices manual, component maintenance manuals, and other 
available resources. For further instruction, these maintenance 
procedures are best obtained from these resources. We have not changed 
the AD in this regard.

Explanation of Change to Applicability

    We have revised the applicability of the existing AD to identify 
model designations as published in the most recent type certificate 
data sheet for the affected models.

Conclusion

    We have carefully reviewed the available data, including the 
comments that have been received, and determined that air safety and 
the public interest require adopting the AD with the changes described 
previously. We have determined that these changes will neither increase 
the economic burden on any operator nor increase the scope of the AD.

Explanation of Change to Costs of Compliance

    Since issuance of the NPRM, we have increased the labor rate used 
in the Costs of Compliance from $80 per work-hour to $85 per work-hour. 
The Costs of Compliance information, below, reflects this increase in 
the specified hourly labor rate.

Costs of Compliance

    There are about 2,699 airplanes of the affected design in the 
worldwide fleet. The following table provides the estimated costs for 
U.S. operators to comply with this AD.

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                            Average                                  Number of
                                   Work      labor                                     U.S.-
            Action                hours     rate per    Parts    Cost per airplane  registered     Fleet cost
                                              hour                                   airplanes
----------------------------------------------------------------------------------------------------------------
Inspection and Torquing                 8        $85         $0  $680, per                 853  $580,040, per
 (required by AD 2007-18-52).                                     inspection cycle.              inspection
                                                                                                 cycle.
Inspection and Modification            18         85      5,388  $6,918...........         853  $5,901,054.
 (new actions).
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[[Page 15812]]

Authority for This Rulemaking

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

Regulatory Findings

    We have determined that this AD will not have federalism 
implications under Executive Order 13132. This AD will not have a 
substantial direct effect on the States, on the relationship between 
the national government and the States, or on the distribution of power 
and responsibilities among the various levels of government.
    For the reasons discussed above, I certify that this AD:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866;
    (2) Is not a ``significant rule'' under DOT Regulatory Policies and 
Procedures (44 FR 11034, February 26, 1979); and
    (3) 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.
    We prepared a regulatory evaluation of the estimated costs to 
comply with this AD and placed it in the AD docket. See the ADDRESSES 
section for a location to examine the regulatory evaluation.

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 Federal Aviation Administration (FAA) amends Sec.  39.13 by 
removing amendment 39-15197 (72 FR 53928, September 21, 2007) and by 
adding the following new airworthiness directive (AD):

2011-06-05 The Boeing Company: Amendment 39-16629. Docket No. FAA-
2009-1253; Directorate Identifier 2009-NM-080-AD.

Effective Date

    (a) This AD becomes effective April 26, 2011.

Affected ADs

    (b) This AD supersedes AD 2007-18-52, Amendment 39-15197.

Applicability

    (c) This AD applies to The Boeing Company Model 737-600, -700, -
700C, -800, -900, and -900ER series airplanes, certificated in any 
category, as identified in Boeing Service Bulletin 737-57A1302, 
Revision 1, dated October 18, 2010.

Subject

    (d) Air Transport Association (ATA) of America Code 57: Wings.

Unsafe Condition

    (e) This AD results from reports of parts coming off the main 
slat track downstop assemblies. The Federal Aviation Administration 
is issuing this AD to prevent loose or missing parts from the main 
slat track downstop assemblies from falling into the slat can and 
causing a puncture, which could result in a fuel leak and consequent 
fire.

Compliance

    (f) You are responsible for having the actions required by this 
AD performed within the compliance times specified, unless the 
actions have already been done.

Restatement of AD 2007-18-52, With No Changes

    Note 1: Paragraph (g) of this AD merely restates the 
requirements of paragraph (f)(1) of emergency AD 2007-18-51 (which 
was superseded by AD 2007-18-52). As allowed by the phrase, ``unless 
the actions have already been done,'' if the applicable initial 
inspections required by paragraph (f)(1) of emergency AD 2007-18-51 
have already been done, this AD does not require that those 
inspections be repeated until the repetitive interval of 3,000 
flight cycles.

Repetitive Detailed Inspections

    (g) Within 10 days after September 26, 2007 (the effective date 
of AD 2007-18-52): Do a detailed inspection or a borescope 
inspection of each main slat track downstop assembly to verify 
proper installation of the slat track hardware (i.e., the bolt, 
washers, downstops, stop location, and nut shown in Figure 1 of 
Boeing Service Letter 737-SL-57-084-B, dated July 10, 2007, and in 
this AD). Proper installation of the sleeve need not be confirmed, 
and the stop location part may be installed on either the inboard or 
the outboard side of the slat track. If any part is missing or is 
installed improperly, before further flight, install a new or 
serviceable part using a method approved in accordance with the 
procedures specified in paragraph (j) of this AD; and do a detailed 
inspection of the inside of the slat can for foreign object debris 
(FOD) and damage. Before further flight, remove any FOD found and 
repair any damage found using a method approved in accordance with 
the procedures specified in paragraph (j) of this AD. Verify proper 
installation; install a new or serviceable part; and inspect for 
damage and FOD, and remove FOD and repair damage; in accordance with 
a method by approved by the Manager, Seattle Aircraft Certification 
Office, FAA; or in accordance with Boeing Multi Operator Message 
Number 1-523812011-1, issued August 25, 2007, or 1-527463441-1, 
issued August 28, 2007. Repeat the actions required by paragraph (g) 
of this AD thereafter at intervals not to exceed 3,000 flight 
cycles.

    Note 2: Paragraph (h) of this AD merely restates the 
requirements of paragraph (f)(2) of emergency AD 2007-18-51. As 
allowed by the phrase, ``unless the actions have already been 
done,'' if the torque application required by paragraph (f)(2) of AD 
emergency 2007-18-51 has already been done, this AD does not require 
that the torque application be repeated.

One-Time Torquing

    (h) Within 24 days after receipt of emergency AD 2007-18-51: 
Apply a torque between 50 to 80 inch-pounds to the nut. The bolt 
head must be held with the torque applied to the nut.

    Note 3: For the purposes of this AD, a detailed inspection is: 
``An intensive examination of a specific item, installation, or 
assembly to detect damage, failure, or irregularity. Available 
lighting is normally supplemented with a direct source of good 
lighting at an intensity deemed appropriate. Inspection aids such as 
mirror, magnifying lenses, etc., may be necessary. Surface cleaning 
and elaborate procedures may be required.''

BILLING CODE 4910-13-P

[[Page 15813]]

[GRAPHIC] [TIFF OMITTED] TR22MR11.075

BILLING CODE 4910-13-C

New Requirements of This AD

Modification and Inspection

    (i) Within 36 months after the effective date of this AD: 
Replace the hardware of the down stop assembly with new hardware, do 
a detailed inspection or a borescope inspection of the slat cans on 
each wing and the lower rail of the slat main tracks for debris, and 
replace the bolts of the aft side guide with new bolts, in 
accordance with Part 2 of the Accomplishment Instructions of Boeing 
Alert Service Bulletin 737-57A1302, dated December 15, 2008; or 
Boeing Service Bulletin 737-57A1302, Revision 1, dated October 18, 
2010; except, where Boeing Alert Service Bulletin 737-57A1302, dated 
December 15, 2008, and Boeing Service Bulletin 737-57A1302, Revision 
1, dated October 18, 2010, specify to replace the slat main track or 
to contact Boeing for further repair instructions if the hole 
diameter is greater than 0.5005 inch, before further flight, replace 
the slat main track in accordance with Boeing Alert Service Bulletin 
737-57A1302, dated December 15, 2008, Boeing Service Bulletin 737-
57A1302, Revision 1, dated October 18, 2010, or repair using a 
method approved in accordance with the

[[Page 15814]]

procedures specified in paragraph (j) of this AD. If debris is found 
during any inspection required by this AD, before further flight, 
remove the debris in accordance with the Accomplishment Instructions 
of Boeing Alert Service Bulletin 737-57A1302, dated December 15, 
2008; or Boeing Service Bulletin 737-57A1302, Revision 1, dated 
October 18, 2010. Doing the actions required by paragraph (i) of 
this AD terminates the actions required by paragraphs (g) and (h) of 
this AD. Installation of stainless steel lockwire having part number 
(P/N) MS20995C32 is acceptable for compliance in lieu of lockwire P/
N MS20995NC32, as specified in Boeing Alert Service Bulletin 737-
57A1302, dated December 15, 2008, for this AD.

Alternative Methods of Compliance

    (j)(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. Or, e-mail information 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 previously in accordance with AD 2007-18-52 
are approved as AMOCs for the corresponding provisions of this AD.

Related Information

    (k) For more information about this AD, contact Nancy Marsh, 
Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle ACO, 
1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone: 
425-917-6440; fax: 425-917-6590; e-mail: nancy.marsh@faa.gov.

Material Incorporated by Reference

    (l) You must use Boeing Alert Service Bulletin 737-57A1302, 
dated December 15, 2008; or Boeing Service Bulletin 737-57A1302, 
Revision 1, dated October 18, 2010; to do the actions required by 
this AD, unless the AD specifies otherwise.
    (1) The Director of the Federal Register approved the 
incorporation by reference of this service information under 5 
U.S.C. 552(a) and 1 CFR part 51.
    (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; e-mail 
me.boecom@boeing.com; Internet https://www.myboeingfleet.com.
    (3) You may review copies of the service information at the FAA, 
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington. For information on the availability of this material at 
the FAA, call 425-227-1221.
    (4) You may also review copies of the service information that 
is incorporated by reference at the National Archives and Records 
Administration (NARA). For information on the availability of this 
material at NARA, call 202-741-6030, or go to: http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.

    Issued in Renton, Washington, on February 23, 2011.
Kalene C. Yanamura,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2011-5301 Filed 3-21-11; 8:45 am]
BILLING CODE 4910-13-P