AD 2018-06-05

We are adopting a new airworthiness directive (AD) for certain The Boeing Company Model 737-300 and -500 series airplanes. This AD was prompted by a report indicating that fatigue cracks were found in the lower wing skin of an airplane with winglets installed. This AD requires repetitive inspections for cracking of the lower wing skin, 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\n2018-06-05 The Boeing Company: Amendment 39-19225; Docket No. FAA- 2017-0903; Product Identifier 2017-NM-074-AD. \n\n(a) Effective Date \n\n\n\tThis AD is effective April 23, 2018. \n\n(b) Affected ADs \n\n\n\tNone. \n\n(c) Applicability \n\n\n\tThis AD applies to The Boeing Company Model 737-300 and -500 series airplanes, certificated in any category, with blended winglet kits installed in accordance with Supplemental Type Certificate (STC) ST01219SE. \n\n(d) Subject \n\n\n\tAir Transport Association (ATA) of America Code 57, Wings. \n\n(e) Unsafe ConditionThis AD was prompted by a report indicating that fatigue cracks were found in the lower wing skin at stringer L-5 of a Boeing Model 737-300 airplane with winglets installed. We are issuing this AD to detect and correct fatigue cracking of the lower wing skin common to the runout of stringer L-5. Such cracking could grow and result in loss of structural integrity of the wing, and consequent reduced, or complete loss of, controllability of the airplane. \n\n(f) Compliance \n\n\n\tComply with this AD within the compliance times specified, unless already done. \n\n(g) Repetitive Inspection \n\n\n\tWithin 18 months after the effective date of this AD: Do a detailed inspection for cracking of the lower wing skin external surface at the stringer L-5 location on the left and right wings, in accordance with the Accomplishment Instructions of Aviation Partners Boeing Service Bulletin AP737C-57-002, dated April 5, 2017. Repeat the inspection thereafter at intervals not to exceed 6,000 flightcycles or 9,000 flight hours, whichever occurs first. \n\n(h) Repair \n\n\n\tIf any crack is found during any inspection required by paragraph (g) of this AD, repair before further flight using a method approved in accordance with the procedures specified in paragraph (i) of this AD. Although Aviation Partners Boeing Service Bulletin AP737C-57-002, dated April 5, 2017, specifies to contact Boeing for repair instructions, and specifies that action as ''RC'' (Required for Compliance), this AD requires repair as specified in this paragraph. \n\n(i) Alternative Methods of Compliance (AMOCs) \n\n\n\t(1) The Manager, Seattle ACO Branch, 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 certification office, send it to the attention of the personidentified in paragraph (j) of this AD. Information may be emailed to: 9-ANM-Seattle-ACO-AMOC-Requests@faa.gov. \n\t(2) Before using any approved AMOC, notify your appropriate principal inspector, or lacking a principal inspector, the manager \n\n((Page 11873)) \n\nof 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, Seattle 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 (h) of this AD: For service information that contains steps that are labeled as RC, the provisions of paragraphs (i)(4)(i) and (i)(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 be put back in an airworthy condition. \n\n(j) Related Information \n\n\n\tFor more information about this AD, contact Lu Lu, Aerospace Engineer, Airframe Section, FAA, Seattle ACO Branch, 2200 South 216th St., Des Moines, WA 98198; phone and fax: 206-231-3525; email: lu.lu@faa.gov. \n\n(k) MaterialIncorporated 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) Aviation Partners Boeing Service Bulletin AP737C-57-002, dated April 5, 2017. \n\t(ii) Reserved. \n\t(3) For service information identified in this AD, contact Aviation Partners Boeing, 2811 South 102nd St., Suite 200, Seattle, WA 98168; phone: 1-206-830-7699; fax: 1-206-767-3355; email: leng@aviationpartners.com; internet: http://www.aviationpartnersboeing.com. \n\t(4) You may view this service information at the FAA, Transport Standards Branch, 2200 South 216th St., Des Moines, WA. For information on the availability of this material at the FAA, call 206-231-3195. \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 certain The Boeing Company Model 737-300 and -500 series airplanes. The NPRM published in the Federal Register on October 6, 2017 (82 FR 46725). The NPRM was prompted by a report indicating that fatigue cracks were found in the lower wing skin of an airplane with winglets installed. The NPRM proposed to require repetitive inspections for cracking of the lower wing skin, and repair if necessary. \n\tWe are issuing this AD to detect and correct fatigue cracking of the lower wing skin common to the runout of stringer L-5. Such cracking could grow and result in loss of structural integrity of the wing, and consequent reduced, or complete loss of, controllability of the airplane. \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. Aviation Partners Boeing concurred with the proposed AD. \n\nRequest for Manufacturer To Share Expense \n\n\n\tOne commenter, Mary Lou Allen, requested that the airplane manufacturer share in the expense with the airplane's purchaser or owner, because of the high costs associated with supplemental type certificates. We infer that the commenter wants manufacturers to be required to help pay for compliance with the proposed AD. \n\tWe do not agree to this request. We provide estimates of the cost on U.S. operators for AD compliance, but do not determine who is responsible for payment. We are aware that airplane manufacturers and modifiers often have warranty agreements with owners and operators to cover some or all of the costs of modifications or repairs, but we do not participate in these agreements. We have not changed this AD in this regard. \n\nConclusion \n\n\n\tWe reviewed the relevant data, considered the comments received, and determined thatair safety and the public interest require adopting this final rule as proposed, except for 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\nRelated Service Information Under 1 CFR Part 51 \n\n\n\tWe reviewed Aviation Partners Boeing Service Bulletin AP737C-57- 002, dated April 5, 2017. The service information describes procedures for repetitive inspections for cracking of the lower wing skin, and repair if necessary. 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\n((Page 11872)) \n\nCosts of Compliance \n\n\n\tWe estimate that this AD affects 93 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 ---------------------------------------------------------------------------------------------------------------- Repetitive inspection............ 1 work-hour x $85 $0 $85 per inspection Up to $7,905 per \n\tper hour = $85 per cycle. inspection cycle. \n\tinspection cycle. ---------------------------------------------------------------------------------------------------------------- \n\n\n\tWe have received no definitive data that would enable 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 in14 CFR Part 39 \n\n\n\tAir transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.