Discussion \n\n\n\tThe EASA, which is the Technical Agent for the Member States of the European Union, has issued EASA AD 2020-0109, dated May 15, 2020 (EASA AD 2020-0109) (also referred to as the Mandatory Continuing Airworthiness Information, or the MCAI), to correct an unsafe condition for certain Airbus SAS Model A350-941 airplanes. \n\tThe FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by adding an AD that would apply to certain Airbus SAS Model A350-941 airplanes. The NPRM published in the Federal Register on August 4, 2020 (85 FR 47122). The NPRM was prompted by a report that during the assembly of the section 19 skin to frame (FR) 98 joint of the fuselage, the gaps found on self-aligning nuts for eight fasteners were out of tolerance. The NPRM proposed to require a rotating probe test of all fastener holes located in the affected area for any discrepancies, an eddy current inspection of the surrounding flange for any discrepancies, a detailed inspection of certain frames for any discrepancies, and corrective actions if necessary, as specified in an EASA AD. \n\tThe FAA is issuing this AD to address gaps that are out of tolerance, which could reduce the fatigue and damage tolerance properties of the affected area, and possibly affect the structural integrity of the rear cone of the fuselage. See the MCAI for additional background information. \n\nComments \n\n\n\tThe FAA 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\nRequest To Revise the Proposed Applicability \n\n\n\tDelta Air Lines, Inc. (DAL) requested that the FAA revise the applicability in the NPRM. DAL stated that the applicability should reflect the effectivity specified in Airbus Service Bulletin A350-53- P057, dated February 21, 2020, and not what is specified in the NPRM and in EASA AD 2020-0109. DAL also stated that the NPRM and EASA AD 2020-0109 would require operators the unnecessary burden of reviewing records and updating associated paperwork to ensure and prove that the proper modification status is embodied on all airplanes, including on any Model A350 airplanes delivered in the future, despite the embodiment of the applicable modification in production. DAL commented that Airbus Service Bulletin A350-53-P057, dated February 21, 2020, specifies specific manufacturer serial numbers and describes which airplanes will have the modification embodied in production (manufacturer serial number 0307 and subsequent). \n\tThe FAA disagrees with the request. The applicability of this AD (and EASA AD 2020-0109) excludes any airplanes on which the modification has been embodied, whether during or after production. EASA, as the State of Design Authority for Airbus products, has determined that this applicability is appropriate because it includes any airplanes on which the modification was not embodied,while excluding those on which the modification has been embodied. The FAA agrees with this decision because it ensures the unsafe condition is addressed on all applicable airplanes. The FAA has not changed the AD in this regard. \n\nRequest To Include Exception To Provide Correct Reference for Installing New Fasteners \n\n\n\tDAL requested that the NPRM be revised to address a discrepancy in a manual reference for installing the new fasteners. DAL noted that Airbus Service Bulletin A350-53-P057, dated February 21, 2020, specifies Airbus task A350-A-53-XX-P057-01001-720A-A and task A350-A- 53-XX-P057-02001-720A-A for instructions to install the new fasteners, and that the actions in those tasks are considered Required for Compliance (RC). DAL asserted that the instructions in those tasks should refer to the Airbus A350 Aircraft Maintenance Manual (AMM) procedure rather than the aircraft structural repair (ASR) manual. DAL pointed out that there is no existing ASR manual with chapter A350-A- 20-51-50-01ZZZ-25BZ-A; however, the AMM reference for standard mechanical torques is maintenance procedure chapter A350-A-20-51-50- 01ZZZ-25BZ-A. DAL stated that Airbus has confirmed in Airbus Technical Request Dossier 80808465 that the correct reference is to the AMM. DAL further requested that, if this discrepancy is not addressed in the AD, it will require that a global alternative method of compliance (AMOC) be requested by Airbus. \n\tThe FAA agrees that the correct document should be referenced for the reasons provided above. The FAA has added paragraph (h)(3) in this AD to clarify that, where Airbus Service Bulletin A350-53-P057, dated February 21, 2020, specifies Airbus task A350-A-53-XX-P057-01001-720A-A and task A350-A-53-XX-P057-02001-720A-A, for instructions for installing the new fasteners, and those instructions specify to refer to ''Ref. ASR A350-A-20-51-01ZZZ-25BZ-A,'' for the purposes of this AD, the correct reference is ''Ref. AMM Maintenance Procedure A350-A-20-51- 01ZZZ-25BZ-A.'' \n\nRequest To Provide Clarification on the Use of Substitute Fasteners \n\n\n\tDAL requested that the FAA provide clarification regarding the use of substitute fasteners. DAL stated that task A350-A-53-XX-P057-01001- 720A-A and task A350-A-53-XX-P057-02001-720A-A, specified in Airbus Service Bulletin A350-53-P057, dated February 21, 2020, provide instructions to install new fasteners. DAL also stated that standard notes within these allow for the use of washers or approved substitute fasteners should the installed fasteners not be sufficient per the standards provided in the ASR manual. DAL questioned whether, since Airbus Service Bulletin A350-53-P057, dated February 21, 2020, provides the specific fasteners to use to address the issue in the NPRM, an AMOC will be required for the use of substitute fasteners despite these notes. \n\tThe FAA agrees to provide clarification. An AMOC is not needed for the use of washers or approved \n\n((Page 86461)) \n\nsubstitute fasteners should the installed fasteners not be sufficient. The FAA has not changed this AD in this regard. \n\nConclusion \n\n\n\tThe FAA reviewed the relevant data, considered the comments received, and determined that air safety and the public interest require adopting this final rule with the change described previously and minor editorial changes. The FAA has determined that these minor changes: \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\tThe FAA also determined that this change 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\tEASA AD 2020-0109 describes procedures for a rotating probe test of all fastener holes located in the affected area for any discrepancies (i.e., cracking or damage), an eddy current inspection of the surrounding flange for any discrepancies, a detailed inspection of FR 97 to FR 99 for any discrepancies, and corrective actions if necessary. Corrective actions include replacing all fasteners located in the affected area with new bolts and self-aligning nuts, and repair. This material 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\tThe FAA estimates that this AD affects 13 airplanes of U.S. registry. The FAA estimates the following costs to comply with this AD: \n\n\n\tEstimated Costs for Required Actions ---------------------------------------------------------------------------------------------------------------- \n\tCost per Cost on U.S. \n\tLabor cost Parts cost product operators ---------------------------------------------------------------------------------------------------------------- 1work-hour x $85 per hour = $85............................. $0 $85 $1,105 ---------------------------------------------------------------------------------------------------------------- \n\n\n\tThe FAA estimates the following costs to do any necessary on- condition replacements that would be required based on the results of any required actions. The FAA has no way of determining the number of aircraft that might need these replacements: \n\n\n\tEstimated Costs of On-Condition Actions * ------------------------------------------------------------------------ \n\tCost per \n\tLabor cost Parts cost product ------------------------------------------------------------------------ 6 work-hours x $85 per hour = $510.... $70 $580 ------------------------------------------------------------------------ \n* The FAA has received no definitive data that would enable providing\n\n\tcost estimates for the on-condition repairs specified in this AD. \n\n\n\tAccording to the manufacturer, some or all of the costs of this AD may be covered under warranty, thereby reducing the cost impact on affected operators. The FAA does not control warranty coverage for affected operators. As a result, the FAA has included all known costs in the cost estimate. \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\tThe FAA is 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 safetyin 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\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) Will not affect intrastate aviation in Alaska, and \n\t(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. \n\nList of Subjects in 14 CFR Part 39 \n\n\n\tAir transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.