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 757 airplanes. The NPRM published in the Federal Register on October 15, 2018 (83 FR 51887). The NPRM was prompted by an evaluation by the DAH indicating that the inner skin of the lap splices, at the lower fastener row, is subject to scratch cracks that may interact with WFD. The NPRM proposed to require a general visual inspection of certain lap splice inspection areas for any repair common to the fuselage skin lap splice inspection areas, repetitive DFEC inspections of a certain lap splice inner skin for any crack, and applicable on- condition actions. \n\tWe are issuing this AD to address scratches that can grow into scratch cracks, which could interact with multi-site damage (MSD) fastener hole fatigue cracking. This condition, if not addressed, could result in accelerated crack growth rate, which could result in reduced structural integrity 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. \n\nEffect of Winglets on Accomplishment of the Proposed Actions \n\n\n\tAviation Partners Boeing stated that accomplishing Supplemental Type Certificate (STC) ST01518SE does not affect the actions specified in the proposed AD. \n\tWe concur with the commenter. 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 ST01518SE does not affect the ability to accomplish the actions required by this AD. Therefore, for airplanes on which STC ST01518SE 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\nRequest for Clarification of the Affected Airplanes \n\n\n\tBoeing requested that we clarify the affected airplanes in the NPRM. Boeing pointed out that the SUMMARY of the NPRM currently states ''for certain The Boeing Company Model 757 airplanes,'' and requested that we change the SUMMARY of the NPRM to state ''for all The Boeing Company Model 757 airplanes.'' \n\tWe acknowledge this typographical error. Boeing Alert Requirements Bulletin 757-53A0111 RB, dated May 21, 2018, specifies ''all The Boeing Company Model 757 airplanes,'' and our intent was to match the service information. We have revised the SUMMARY and paragraph (c)(1) of this AD accordingly. \n\nRequest To Revise the Safety Issue \n\n\n\tBoeing requested that we clarify the nature of the safety issue. Boeing pointed out that the SUMMARY of the NPRM suggests that the safety issue is limited to WFD. Boeing also mentioned that lap splice WFD for the Model 757 fleet is already addressed by AD 2018-18-07, Amendment 39-19386 (83 FR \n\n((Page 15950))45037, September 5, 2018) (''AD 2018-18-07''). Boeing specified that the safety issue that the NPRM is mitigating is the potential for interaction between MSD and scratch cracks on the inner skin of the lap splices. Boeing requested that we revise the ''prompted by'' statement in the SUMMARY of the NPRM to specify ''. . . at the lower fastener row is subject to scratch cracks that may interact with WFD.'' \n\tWe acknowledge the commenter's concern. As written, the SUMMARY of the NPRM can be misconstrued to specify duplicate actions (lap splice WFD) already addressed by AD 2018-18-07. The intent of this AD action is to address the potential for interaction between MSD and scratch cracks on the inner skin of the lap splices. Therefore, we have revised the SUMMARY and paragraph (e) of this AD accordingly. \n\nRequest for Clarification of the GVI Inspection Area \n\n\n\tBoeing requested that we clarify the GVI inspection area. Boeing mentioned that the SUMMARY and ''Related Service Information Under 1 CFR part 51'' section of the NPRM each describe a GVI common to the fuselage skin lap splice inspection areas. Boeing pointed out that the wording seems confusing and could be perceived as a circular description (i.e. that the inspection area is common to the inspection area). Boeing also pointed out that there is no mention of the commonality of the DFEC inspection areas and the GVI inspection areas. \n\tWe agree with the commenter's request for the reasons provided. We have revised the SUMMARY and ''Related Service Information Under 1 CFR part 51'' section of this AD accordingly. \n\nRequest for Clarification of the Affected Inspection Area \n\n\n\tBoeing requested that we clarify the affected inspection area. Boeing mentioned that the SUMMARY of the NPRM states ''. . . DFEC inspections of a certain lap splice inner skin. . . .'' Boeing pointed out that this statement suggests that only one skin panel is affected. Boeing requested that we revise the SUMMARY of the NPRM to state ''. . . DFEC inspections of certain lap splice inner skins. . . .'' \n\tWe agree with the commenter's request for the reasons provided. We have revised the SUMMARY of this AD accordingly. \n\nRequest To Clarify That the Inspections Are Not Limited to Lap Splices at Stringer (S) 14 \n\n\n\tBoeing requested that we clarify that the inspections are not limited to lap splices at S-14. Boeing mentioned that the ''Related Service Information Under 1 CFR part 51'' section of the NPRM describes the service information as procedures for ''. . . repetitive DFEC inspections of the S-14 lap splice inner skin for any crack . . . .'' Boeing pointed out that the description does not mention any of the other lap splice stringer locations where the inspections are required. Boeing requested that we revise the description to specify ''. . . repetitive DFEC inspections of certain lap splice inner skins for any crack . . . .'' \n\tWe agree with the commenter's request for the reasons provided. We have revised the ''Related Service Information Under 1 CFR part 51'' section of this AD accordingly. \n\nRequest To Revise the Costs of Compliance of the NPRM \n\n\n\tBoeing requested that we clarify the Costs of Compliance of the NPRM. Boeing mentioned that the NPRM specified 451 airplanes of U.S. registry. Boing specified that its records show there to be 561 airplanes of U.S. registry that would be affected by the NPRM. Boeing also pointed out that the difference in affected airplanes significantly increases the overall costs to the U.S. registered Model 757 fleet. \n\tWe agree that Boeing records account for U.S. registered airplanes that the FAA did not include in the NPRM, and that this number may be a more accurate representation of the U.S. registered airplanes. We did not originally include airplanes in our cost estimate that are in storage or not currently active. We have updated the Costs of Compliance section of this AD to reflect the specific number of U.S. registered airplanesand the revised cost on U.S. operators. \n\nRequest To Include Required for Compliance (RC) Language \n\n\n\tBoeing requested that we revise paragraph (i) of the proposed AD to include RC language. Boeing mentioned that this change would clarify which actions are mandated. \n\tWe agree that clarification is necessary, however, we disagree with the request to include RC language in paragraph (i) of this AD. As noted in Boeing Alert Requirements Bulletin 757-53A0111 RB, dated May 21, 2018, if an RB is mandated by an AD, then all applicable requirements specified in the RB must be done. We did not include RC language because this AD requires accomplishment of all the actions specified in the Accomplishment Instructions of Boeing Alert Requirements Bulletin 757-53A0111 RB, dated May 21, 2018. Therefore, we have not changed this AD in this regard. \n\nRequest To Exclude Airplanes With Certain Modifications \n\n\n\tFedEx and VT Mobile Aerospace Engineering (MAE) Inc. requested that we revise the NPRM to specify that inspections, methods, and compliance times regarding certain lap splices specified in Boeing Alert Requirements Bulletin 757-53A0111 RB, dated May 21, 2018, be omitted for the FedEx fleet of Model 757-200 airplanes. FedEx mentioned that its fleet has been modified using certain VT MAE Inc. supplemental type certificates (STCs), and is no longer configured as passenger airplanes. FedEx pointed out that its Model 757-200 fleet is identified as Groups 1, 4, and 5 in Boeing Alert Requirements Bulletin 757-53A0111 RB, dated May 21, 2018. VT MAE Inc. pointed out that because of the change in configuration related to the VT MAE Inc. STCs, certain lap splice inspection areas have been removed and those airplanes are unable to fully comply with the inspection procedures specified in Boeing Alert Requirements Bulletin 757-53A0111 RB, dated May 21, 2018. VT MAE Inc. proposed certain exceptions to the service information in the final rule. The proposed exceptions are for the lap splice inspections affected by the change in configuration related to the VT MAE Inc. STCs. FedEx requested that, in lieu of requesting an AMOC after publication, we include the exceptions proposed by VT MAE Inc. in the final rule. \n\tWe acknowledge the commenters' remarks, however, we disagree with the request to include exceptions in this final rule that are specific to certain airplanes operated by FedEx. There are many different airplane configurations across multiple operators, and ADs cannot accommodate all possible configurations. However, under the provisions of paragraph (i) of this AD, we will consider requests for approval of an AMOC that addresses the VT MAE Inc. STCs, if appropriate data are submitted to substantiate that the method would provide an acceptable level of safety. 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 that air safety and the public interest requireadopting this final rule with the changes described previously and minor editorial changes. We have determined that these minor changes: \n\n((Page 15951)) \n\n\n\tAre consistent with the intent that was proposed in the NPRM for addressing 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 Requirements Bulletin 757-53A0111 RB, dated May 21, 2018. This service information describes procedures for a GVI of certain lap splice inspection areas for any repair common to the fuselage skin lap splice DFEC inspection areas, repetitive DFEC inspections of certain lap splice inner skins for any crack, and applicable on-condition actions. 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 561 airplanes of U.S. registry. We estimate the following costs to comply with this AD: \n\n\n\tEstimated Costs for Required Actions ---------------------------------------------------------------------------------------------------------------- \n\tCost on U.S. \n\tAction Labor cost Parts cost Cost per product operators ---------------------------------------------------------------------------------------------------------------- General visual inspection........ Up to 6 work-hours $0 Up to $510......... Up to $286,110. \n\tx $85 per hour = \n\tup to $510. Repetitive DFEC inspections...... Up to 124 work- $0 Up to $10,540 per Up to $5,912,940 \n\thours x $85 per inspection cycle. per inspection \n\thour = up tocycle. \n\t$10,540 per \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 forsafety 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 and associated appliances 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.