Discussion \n\n\n\tWe issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to supersede AD 2013-01-02, Amendment 39-17316 (78 FR 4051, January 18, 2013) (''AD 2013-01-02''). AD 2013-01-02 applied to certain The Boeing Company Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F, 747SR, and 747SP series airplanes; and Model 757-200, 757-200PF, and 757-300 series airplanes. The NPRM published in the Federal Register on October 6, 2017 (82 FR 46722). The NPRM was prompted by reports of uncommanded cargo door operation. The NPRM proposed to require replacement of certain cargo door control switches with a new, improved switch; installation of an arm switch in certain cargo doors; operational and functional tests; and applicable on-condition actions. The NPRM also proposed to add airplanes to the applicability. We are issuing this AD to prevent failures of the cargo door control switch from allowing uncommanded movement of the cargo door, which, if not corrected, could lead to injuries to persons and damage to the airplane. \n\nComments \n\n\n\tWe gave the public the opportunity to participate in developing this AD. The following presents the comments received on the NPRM and the FAA's response to each comment. \n\nSupport for the NPRM \n\n\n\tFedEx Express and United Airlines (UAL) stated they had no technical objection to the NPRM. \n\nRequest To Withdraw the NPRM \n\n\n\tThree commenters requested that the NPRM be withdrawn. Virgin Atlantic Airlines (VAA) and Deutsche Lufthansa AG (DLH) pointed out there have been no reported failures of the cargo door control switches or incidents of uncommanded door operation at VAA or DLH since AD 2013- 01-02 was issued. United Parcel Service (UPS) stated that the NPRM appears to be based on a single event of an otherwise reliable cargo door switch configuration, based on industry data that show no significant number of unscheduled removals reported since AD 2013-01-02 was issued. DLH commented that the operational area of the cargo door is a safety critical area that requires the operator to verify that the area is safe and clear, whether an additional arm switch is present or not. All commenters stated that the repetitive inspections required by AD 2013-01-02 should remain in place and that accomplishing the actions in Boeing Special Attention Service Bulletin 747-52-2307, dated May 23, 2017; and Boeing Special Attention Service Bulletin 747-52-2308, dated June 5, 2017; should be an optional terminating action for the inspections. \n\tWe disagree with the commenters' request because our risk analysis indicates that the actions mandated by AD 2013-01-02 were inadequate to mitigate the unsafe condition. Although VAA and DLH have had no new incidents, there have been multiple reports of uncommanded cargo door operation within the affected fleets. Therefore, existing procedures for door operation have not been adequateto prevent the unsafe condition. We are mandating the actions in this AD because an unsafe condition exists, which is likely to exist or develop on other products of the same type design. We have not changed this AD in this regard. \n\n((Page 49781)) \n\nRequest To Specify Compliance Times Using Flight Cycles \n\n\n\tUPS requested that we specify compliance times in terms of flight cycles rather than calendar time because cargo door operation is based on flight cycles. UPS also stated that the compliance interval for both Model 747 and 757 fleets should be the same because the operation of the cargo door control switch is the same across both models. UPS recommended replacing the cargo door control switches every 3,000 flight cycles. \n\tWe disagree with the commenter's request because we have not confirmed a causal relationship between switch failure and operating cycles. In developing the compliance time in this AD, we have considered the safety implications, parts availability, and normal maintenance schedules for the timely installation of the cargo door control switches. Further, the compliance time in this AD corresponds with the manufacturer's recommended compliance time for each model. If we receive additional data that justify a different compliance time, we may consider further rulemaking on this issue. In addition, under the provisions of paragraph (j) of this AD, we will consider requests for approval of alternative compliance times if sufficient data are submitted to substantiate that the change would provide an acceptable level of safety. We have not changed this AD in this regard. \n\nRequest To Include Latest Service Information Revision \n\n\n\tAAL, Delta Airlines (DAL), and FedEx Express requested that we refer to Boeing Special Attention Service Bulletin 757-52-0093, Revision 2, dated November 14, 2017, instead of Boeing Special Attention Service Bulletin 757-52-0093, Revision 1, dated April 21, 2017, which is referenced in the NPRM. DAL stated thatthe revised service information allows alternatives to Alodine 1200 and 1200S. AAL noted that paragraphs (c)(4) and (g)(4) of the proposed AD would no longer be necessary as the new service information addresses those issues. AAL also requested that we provide credit for Boeing Special Attention Service Bulletin 757-52-0093, Revision 1, dated April 21, 2017. \n\tWe agree with the commenters' request. Boeing Special Attention Service Bulletin 757-52-0093, Revision 2, dated November 14, 2017, provides minor corrections, and there is no effect on airplanes on which earlier revisions were done. Boeing Special Attention Service Bulletin 757-52-0093, Revision 2, dated November 14, 2017, also adds variable numbers NP901 through NP904 inclusive to the effectivity. We had referred to those variable numbers in paragraphs (c)(4) and (g)(4) of the proposed AD. Therefore, we have made the following changes to this AD: \n\tChanged paragraphs (c)(3) and (g)(3) of this AD to refer to Boeing Special Attention Service Bulletin 757-52-0093, Revision 2, dated November 14, 2017. \n\tRemoved paragraphs (c)(4) and (g)(4) of the proposed AD. \n\tChanged this AD to provide credit for certain actions done before the effective date of this AD using Boeing Special Attention Service Bulletin 757-52-0093, Revision 1, dated April 21, 2017 (reference paragraph (i)(3) of this AD). \n\nRequest To Extend Compliance Time \n\n\n\tMultiple commenters requested that we extend the compliance times in the proposed AD. DLH requested we extend the compliance time on the Model 747 airplanes from 35 months to 72 months because there have been no recorded cargo door control switch failures since AD 2013-01-02 was issued. American Airlines (AAL) requested that for the requirement to replace the cargo door control switches on Model 757 airplane cargo doors 1 and 2, we extend the compliance time from 24 months to 36 months. AAL explained that new cargo door control switches will have already been installed as part of compliance with AD 2013-01-02, and proposed accomplishing a functional check of the cargo door control switch every 12 months until cargo door control switches are replaced in accordance with Boeing Special Attention Service Bulletin 757-52- 0093, Revision 2, dated November 14, 2017. \n\tWe disagree with extending the compliance times in this AD because we have determined that the replacements required by AD 2013-01-02 are inadequate, and that new, improved switches are necessary to address the unsafe condition. In developing the compliance times in this AD, we have considered the safety implications, parts availability, and normal maintenance schedules for the timely installation of the cargo door control switches. Further, the compliance times in this AD correspond with the manufacturer's recommended compliance time for each model. If we receive additional data that justify different compliance times, we may consider further rulemaking on this issue. In addition, under the provisions of paragraph (j) of this AD, we will consider requests for approval of alternative compliance times if sufficient data are submitted to substantiate that the change would provide an acceptable level of safety. We have not changed this AD in this regard. \n\nRequest for Relief Due to Parts Availability \n\n\n\tCathay requested a non-specific extension of the compliance times due to parts availability issues. Cathay stated that paragraphs (g)(1) and (g)(2) of the proposed AD would require accomplishment of applicable actions in accordance with Boeing Special Attention Service Bulletin 747-52-2307, dated May 23, 2017; and Boeing Special Attention Service Bulletin 747-52-2308, dated June 5, 2017. Cathay noted that both service bulletins specify a compliance time of 35 months after the ''original issue date of the service bulletin'' (e.g., May 23, 2017; and June 5, 2017, respectively). The commenter stated it had received information from Boeing that certain parts were not ready for deliverydue to issues during validation of Boeing Special Attention Service Bulletin 747-52-2307, dated May 23, 2017. The commenter also stated that Boeing Special Attention Service Bulletin 747-52-2308, dated June 5, 2017, has not been validated. \n\tRegarding Cathay's comment that certain compliance times are relative to the issue dates of Boeing Special Attention Service Bulletin 747-52-2307, dated May 23, 2017; and Boeing Special Attention Service Bulletin 747-52-2308, dated June 5, 2017, we agree to clarify the required compliance times. Paragraph (g) of this AD states ''Except as required by paragraph (h) of this AD,'' and paragraph (h) of this AD specifies that certain compliance times are relative to the ''effective date of this AD,'' rather than the ''original issue date of this service bulletin.'' Therefore, the compliance times in this AD are based on the effective date of this AD instead of the issue date of applicable service bulletins. \n\tThe Boeing Company has completed the validation process for all applicable service information. Revised and validated service information for the Model 747 airplanes is now available. This AD references the revised service information as the appropriate source of service information for affected Boeing Model 747 series airplanes. In addition, Boeing has informed us that parts are currently available for compliance with this AD. \n\tWe have changed paragraphs (c)(1) and (g)(1) of this AD to refer to Boeing Special Attention Service Bulletin 747-52-2307, Revision 1, dated May 2, 2018; \n\n((Page 49782)) \n\nand paragraphs (c)(2) and (g)(2) of this AD to reference Boeing Special Attention Service Bulletin 747-52-2308, Revision 1, dated June 18, 2018. We have also changed paragraph (h) of this AD to refer to Boeing Special Attention Service Bulletin 747-52-2307, Revision 1, dated May 2, 2018; and Boeing Special Attention Service Bulletin 747-52-2308, Revision 1, dated June 18, 2018. We have also changed this AD to provide credit for certain actions done before the effective date of this AD using Boeing Special Attention Service Bulletin 747-52-2307, dated May 23, 2017, or Boeing Special Attention Service Bulletin 747- 52-2308, dated June 5, 2017, as applicable (reference paragraphs (i)(1) and (i)(2) of this AD). \n\tSince parts and revised service information are available, and since the compliance times are based on the effective date of this AD, rather than the service information, we have not changed the compliance times in this AD in this regard. However, under the provisions of paragraph (j) of this AD, we will consider requests for approval of alternative compliance times if sufficient data are submitted to substantiate that the change would provide an acceptable level of safety. \n\nRequest To Remove Replacement Requirement for Certain Airplanes \n\n\n\tBoeing requested we revise the language in paragraph (g)(4) of the proposed AD to remove the requirement to replace the nose cargo door control switch fromthe Model 757 airplane requirements because Model 757 airplanes do not have a nose cargo door. \n\tWe agree with the commenter's request for the reasons provided by the commenter. As stated previously, paragraph (g)(4) of the proposed AD is not retained in this AD. The actions for Model 757 airplanes, which are required by paragraph (g)(3) of this AD, are specified in Boeing Special Attention Service Bulletin 757-52-0093, Revision 2, dated November 14, 2017, which does not reference nose cargo door switches. \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 AD 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 addressing the unsafe condition; and \n\tDo not add any additional burden upon the public than was already proposed in the NPRM. \n\tWe alsodetermined that these changes will not increase the economic burden on any operator or increase the scope of this AD. \n\nRelated Service Information Under 1 CFR Part 51 \n\n\n\tWe reviewed the following Boeing service information. \n\tBoeing Special Attention Service Bulletin 747-52-2307, Revision 1, dated May 2, 2018; and Boeing Special Attention Service Bulletin 747-52-2308, Revision 1, dated June 18, 2018. The service information describes procedures for replacement of the nose, forward, and aft cargo door control switches with new, improved switches; installation of an arm switch in the forward and aft cargo doors; a nose cargo door normal operation test; forward and aft cargo door open and close functional tests; and applicable on-condition actions. These documents are distinct since they apply to different airplanes in different configurations. \n\tBoeing Special Attention Service Bulletin 757-52-0093, Revision 2, dated November 14, 2017. This service information describes procedures for replacement of the forward and aft cargo door control switches with new, improved switches; installation of an arm switch in the forward and aft cargo doors; an operational test of the No. 1 and No. 2 cargo doors; repetitive functional tests of the No. 1 and No. 2 cargo doors; and applicable on-condition actions. \n\tThis 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 584 airplanes of U.S. registry. We estimate the following costs to comply with this AD: \n\n\n\tEstimated Costs -------------------------------------------------------------------------------------------------------------------------------------------------------- \n\tAction Labor cost Parts cost Cost per product Cost on U.S. operators -------------------------------------------------------------------------------------------------------------------------------------------------------- Replacement (Boeing Special Attention 78 work-hours x $85 per $12,874 $19,504.................. $273,056. \n\tService Bulletin 747-52-2307) (14 hour = $6,630. \n\tairplanes). Replacement (Boeing Special Attention 24 work-hours x $85 per 980 3,020.................... 283,880. \n\tService Bulletin 747-52-2308) (94 hour = $2,040. \n\tairplanes). Replacement (Boeing Special Attention 51 work-hours x $85 per 10,626 14,961................... 7,121,436. \n\tService Bulletin 757-52-0093) (476 hour = $4,335. \n\tairplanes). Repetitive Test (Boeing Special 3 work-hours x $85 per 0 255 per test cycle....... 121,380 per test cycle. \n\tAttention Service Bulletin 757-52- hour = $255 per test \n\t0093) (476 airplanes). cycle. -------------------------------------------------------------------------------------------------------------------------------------------------------- \n\n\n\tAccording to the manufacturer, some of the costs of this AD may be covered under warranty, thereby reducing the cost impact on affected individuals. We do not control warranty coverage for affected individuals. As a result, we have included all available costs in our 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\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 \n\n((Page 49783)) \n\nDivision, 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\tWe 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 betweenthe 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.