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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
 AGENCY: Federal Aviation Administration (FAA), Department of Transportation (DOT).
 ACTION: Final rule.
 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, 
                    ( print 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 
                    ( print 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 
                    ( print 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
Action
Work hours
Average labor rate per hour
Parts
Cost per airplane
Number of U.S.-registered airplanes
Fleet costInspection and Torquing (required by AD 2007-18-52)
8
$85
$0
$680, per inspection cycle
853
$580,040, per inspection cycle.Inspection and Modification (new actions)
18
85
5,388
$6,918
853
$5,901,054.
 
 
 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
 1.The authority citation for part 39 continues to read as follows: Authority:
                        49 U.S.C. 106(g), 40113, 44701. § 39.13
 2.The Federal Aviation Administration (FAA) amends § 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.” 
 
  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 
                            ( print 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.


BILLING CODE 4910-13-P BILLING CODE 4910-13-C [FR Doc. 2011-5301 Filed 3-21-11; 8:45 am]