AD 2017-24-05

We are adopting a new airworthiness directive (AD) for all The Boeing Company Model 737-100, -200, -200C, -300, -400, and -500 series airplanes. This AD was prompted by reports of cracking in the upper aft skin at the rear spar of the wings. This AD requires repetitive inspections for cracking of the upper aft skin of the wings, and repair if necessary. We are issuing this AD to address the unsafe condition on these products.

Final rule.

Adoption of the Amendment \n\n\n\tAccordingly, under the authority delegated to me by the Administrator, the FAA amends 14 CFR part 39 as follows: \n\nPART 39--AIRWORTHINESS DIRECTIVES \n\n0 1. The authority citation for part 39 continues to read as follows: \n\n\n\tAuthority: 49 U.S.C. 106(g), 40113, 44701. \n\n\n\nSec. 39.13 (Amended) \n\n0 2. The FAA amends Sec. 39.13 by adding the following new airworthiness directive (AD): \n\n2017-24-05 The Boeing Company: Amendment 39-19109; Docket No. FAA- 2017-0526; Product Identifier 2017-NM-026-AD. \n\n(a) Effective Date \n\n\n\tThis AD is effective January 2, 2018. \n\n(b) Affected ADs \n\n\n\tNone. \n\n(c) Applicability \n\n\n\t(1) This AD applies to all The Boeing Company Model 737-100, -.200, -.200C, -.300, -.400, and -.500 series airplanes, certificated in any category. \n\t(2) Installation of Supplemental Type Certificate (STC) ST01219SE (http://rgl.faa.gov/Regulatory_and_Guidance_Library/ rgstc.nsf/0/48e13cdfbbc32cf4862576a4005d308b/$FILE/ST01219SE.pdf) does not affect the ability to accomplish the actions required by this AD. Therefore, for airplanes on which STC ST01219SE is installed, a ''change in product'' alternative method of compliance (AMOC) approval request is not necessary to comply with the requirements of 14 CFR 39.17. \n\n(d) Subject \n\n\n\tAir Transport Association (ATA) of America Code 57; Wings. \n\n(e) Unsafe Condition \n\n\n\tThis AD was prompted by reports of cracking in the upper aft skin at the rear spar of the wings. We are issuing this AD to detect and correct cracks in the upper aft skin of the wings, which could result in the inability of a principal structural element to sustain limit load, and consequent reduced structural integrity of the airplane. \n\n((Page 56158)) \n\n(f) Compliance \n\n\n\tComply with this AD within the compliance times specified, unless already done. \n\n(g) For Group 1 Airplanes: Inspection and Corrective Actions \n\n\n\tFor airplanes identified as Group 1 in Boeing Alert Service Bulletin 737-57A1329, dated January 16, 2017: Within 120 days after the effective date of this AD, do an inspection for cracking of the upper aft skin of the wings, and do all applicable corrective actions, using a method approved in accordance with the procedures specified in paragraph (j) of this AD. \n\n(h) For Groups 2 and 3 Airplanes: Repetitive Inspections and Repair \n\n\n\tFor Groups 2 and 3 airplanes identified in Boeing Alert Service Bulletin 737-57A1329, dated January 16, 2017: At the applicable time specified in paragraph 1.E., ''Compliance,'' of Boeing Alert Service Bulletin 737-57A1329, dated January 16, 2017, except as required by paragraph (i) of this AD, do the applicable inspection for cracking of the upper aft skin of the wings from wing buttock line (WBL) 159 to WBL 220, in accordance with the Work Instructions of Boeing Alert Service Bulletin 737-57A1329, dated January 16, 2017. If any cracking is found, repair before further flight, in accordance withthe procedures specified in paragraph (j) of this AD. Repeat the inspection thereafter at the applicable time specified in paragraph 1.E., ''Compliance,'' of Boeing Alert Service Bulletin 737-57A1329, dated January 16, 2017. \n\n(i) Exceptions to the Service Information \n\n\n\t(1) Where Boeing Alert Service Bulletin 737-57A1329, dated January 16, 2017, specifies a compliance time ''after the original issue date of this service bulletin,'' paragraph (h) of this AD requires compliance within the specified compliance time after the effective date of this AD. \n\t(2) Although Boeing Alert Service Bulletin 737-57A1329, dated January 16, 2017, specifies to contact Boeing for repair instructions, and specifies that action as ''RC'' (Required for Compliance), this AD requires repair in accordance with the procedures specified in paragraph (j) of this AD. \n\n(j) Alternative Methods of Compliance (AMOCs) \n\n\n\t(1) The Manager, Los Angeles ACO Branch, FAA, has the authority to approve AMOCs forthis 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 certification office, send it to the attention of the person identified in paragraph (k) of this AD. Information may be emailed to: 9-ANM-LAACO-AMOC-Requests@faa.gov. \n\t(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. \n\t(3) An AMOC that provides an acceptable level of safety may be used for any repair, modification, or alteration required by this AD if it is approved by the Boeing Commercial Airplanes Organization Designation Authorization (ODA) that has been authorized by the Manager, Los Angeles ACO Branch, to make those findings. To be approved, the repair method, modification deviation, or alteration deviation must meet the certification basis of the airplane, and the approval must specifically refer to this AD. \n\t(4) Except as required by paragraph (i)(2) of this AD: For service information that contains steps that are labeled as RC, the provisions of paragraphs (j)(4)(i) and (j)(4)(ii) of this AD apply. \n\t(i) The steps labeled as RC, including substeps under an RC step and any figures identified in an RC step, must be done to comply with the AD. If a step or substep is labeled ''RC Exempt,'' then the RC requirement is removed from that step or substep. An AMOC is required for any deviations to RC steps, including substeps and identified figures. \n\t(ii) Steps not labeled as RC may be deviated from using accepted methods in accordance with the operator's maintenance or inspection program without obtaining approval of an AMOC, provided the RC steps, including substeps and identified figures, can still be done as specified, and the airplane can beput back in an airworthy condition. \n\n(k) Related Information \n\n\n\tFor more information about this AD, contact Payman Soltani, Aerospace Engineer, Airframe Section, FAA, Los Angeles ACO Branch, 3960 Paramount Boulevard, Lakewood, CA 90712-4137; phone: 562-627- 5313; fax: 562-627-5210; email: payman.soltani@faa.gov. \n\n(l) Material Incorporated by Reference \n\n\n\t(1) The Director of the Federal Register approved the incorporation by reference (IBR) of the service information listed in this paragraph under 5 U.S.C. 552(a) and 1 CFR part 51. \n\t(2) You must use this service information as applicable to do the actions required by this AD, unless the AD specifies otherwise. \n\t(i) Boeing Alert Service Bulletin 737-57A1329, dated January 16, 2017. \n\t(ii) Reserved. \n\t(3) For service information identified in this AD, contact Boeing Commercial Airplanes, Attention: Contractual & Data Services (C&DS), 2600 Westminster Blvd., MC 110-SK57, Seal Beach, CA 90740; telephone 562-797-1717; Internet https://www.myboeingfleet.com. \n\t(4) You may view this service information at the FAA, Transport Standards Branch, 1601 Lind Avenue SW., Renton, WA. For information on the availability of this material at the FAA, call 425-227-1221. \n\t(5) You may view this service information that is incorporated by reference at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 202-741-6030, or go to: http://www.archives.gov/federal-register/cfr/ibr-locations.html.

Discussion \n\n\n\tWe issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by adding an AD that would apply to all The Boeing Company Model 737-100, -200, -200C, -300, -400, and -500 series airplanes. The NPRM published in the Federal Register on June 5, 2017 (82 FR 25744). The NPRM was prompted by reports of cracking in the upper aft skin at the rear spar of the wings. The NPRM proposed to require repetitive inspections for cracking of the upper aft skin of the wings, and repair if necessary. \n\nComments \n\n\n\tWe gave the public the opportunity to participate in developing this final rule. The following presents the comments received on the NPRM and the FAA's response to each comment. \n\nEffect of Winglets on Accomplishment of the Proposed Actions \n\n\n\tAviation Partners Boeing (APB) stated that the installation of winglets per Supplemental Type Certificate (STC) ST01219SE does not affect the accomplishment of the manufacturer's service instructions. \n\tSouthwest Airlines requested clarification that additional alternative method of compliance (AMOC) approvals are not necessary during accomplishment of the actions specified in Boeing Alert Service Bulletin 737-57A1329, dated January 16, 2017, if the installation of winglets was done using STC ST01219SE. \n\tWe agree with the commenters' statements. We have redesignated paragraph (c) of the proposed AD as paragraph (c)(1) of this AD and added paragraph (c)(2) to this AD to state that installation of STC ST01219SE does not affect the ability to accomplish the actions required by this AD. Therefore, for airplanes on which STC ST01219SE is installed, a ''change in product'' AMOC approval request is not necessary to comply with the requirements of 14 CFR 39.17. \n\nRequest To Revise Certain Corrective Action Requirements \n\n\n\tAll Nippon Airways (ANA) asked that we revise paragraph (h) of the proposed AD to change the compliance method for crack repair to allow use of the Boeing 737-500 Structural Repair Manual (SRM) 57-20-10, Repair 7. ANA stated that Boeing has already developed the repair procedure for the outer wing upper aft skin at the trailing edge between wing buttock line (WBL) 160 and WBL 205, as specified in Boeing 737-500 SRM 57-20-10, Repair 7. ANA added that the repair procedure is applicable to part of an inspection area specified in Boeing Alert Service Bulletin 737-57A1329, dated January 16, 2017. ANA noted that its request should be considered to reduce AMOC requests. \n\tWe disagree with the request. Boeing has indicated that Repair 7 of the SRM is currently being revised. We do not consider that delaying this rulemaking until release of the revised service information is warranted. However, under the provisions of paragraph (j) of this AD, we will consider requests for approval of alternative service information if sufficient data are submitted to substantiate that the service information would provide an acceptable level of safety. Boeing has indicated it intends to request approval of a global AMOC for the revised service information after this AD is published. Therefore, we have made no change to this AD in this regard. \n\nRequest To Clarify Certain Requirements \n\n\n\tBoeing asked that paragraph (g) of the proposed AD, and the heading for paragraph (g), be changed to include ''corrective actions'' to clarify that corrective actions may be required. \n\tWe agree with the commenter's request. We have revised paragraph (g) of this AD accordingly. \n\tBoeing also asked that the header for paragraph (h) of the proposed AD be changed to remove ''repetitive'' because merely specifying ''inspections'' addresses both initial and repetitive inspections. \n\tWe agree to clarify the terminology in the header for paragraph (h) of this AD. We do not presume that the term ''repetitive'' necessarily excludes the initial action. An action cannot be repeated without accomplishment of the initial action. Many existing ADs use the term ''repetitive'' actions, which we intend as including the initial action. Therefore, we have not changed this AD regarding this issue. \n\n((Page 56157)) \n\nConclusion \n\n\n\tWe reviewed the relevant data, considered the comments received, and determined that air safety and the public interest require adopting this final rule with the changes described previously and minor editorial changes. We have determined that these minor changes: \n\tAre consistent with the intent that was proposed in the NPRM for correcting the unsafe condition; and \n\tDo not add any additional burden upon the public than was already proposed in the NPRM. \n\tWe also determined that these changes will not increase the economic burden on any operator or increase the scope of this final rule. \n\nRelated Service Information Under 1 CFR Part 51 \n\n\n\tWe reviewed Boeing Alert Service Bulletin 737-57A1329, dated January 16, 2017. The service information describes procedures for repetitive surface high frequencyeddy current inspections, low frequency eddy current inspections, and detailed inspections on airplanes with or without an external repair, for cracking of the upper aft skin from WBL 159 to WBL 220. This service information is reasonably available because the interested parties have access to it through their normal course of business or by the means identified in the ADDRESSES section. \n\nCosts of Compliance \n\n\n\tWe estimate that this AD affects 471 airplanes of U.S. registry. We estimate the following costs to comply with this AD: \n\n\n\tEstimated Costs ---------------------------------------------------------------------------------------------------------------- \n\tCost on U.S. \n\tAction Labor cost Parts cost Cost per product operators ---------------------------------------------------------------------------------------------------------------- Inspection.............. Up to 9 work-hours x $85 $0 Up to $765 perUp to $360,315 per \n\tper hour = up to $765 per inspection cycle. inspection cycle. \n\tinspection cycle. ---------------------------------------------------------------------------------------------------------------- \n\n\n\tWe have received no definitive data that enables us to provide cost estimates for the on-condition actions specified in this AD. \n\nAuthority for This Rulemaking \n\n\n\tTitle 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. \n\tWe 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. \n\tThis AD is issued in accordance with authority delegated by the Executive Director, Aircraft Certification Service, as authorized by FAA Order 8000.51C. In accordance with that order, issuance of ADs is normally a function of the Compliance and Airworthiness Division, but during this transition period, the Executive Director has delegated the authority to issue ADs applicable to transport category airplanes to the Director of the System Oversight Division. \n\nRegulatory Findings \n\n\n\tThis 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. \n\tFor the reasons discussed above, I certify that this AD: \n\t(1) Is not a ''significant regulatory action'' under Executive Order 12866, \n\t(2) Is not a ''significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979), \n\t(3) Will not affect intrastate aviation in Alaska, and \n\t(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. \n\nList of Subjects in 14 CFR Part 39 \n\n\n\tAir transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.