Discussion \n\n\n\tThe FAA 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 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747- 400F, 747-8F, and 747-8 series airplanes. The NPRM published in the Federal Register on April 8, 2019 (84 FR 13840). The NPRM was prompted by reports of uncommanded fore and aft movement of the Captain's and First Officer's seats. The NPRM proposed to require, for the Captain's and First Officer's seats, repetitive horizontal actuator identifications, repetitive checks of the HMS, a detailed inspection of the HMS for certain airplanes, and applicable on-condition actions. The NPRM also proposed to require an inspection to determine the part number and, if applicable, the serial number of the Captain's and First Officer's seats and applicable on-condition actions. The NPRM also proposed to provide an optional terminating action for therepetitive actions for certain seats. \n\tThe FAA is issuing this AD to address uncommanded fore and aft movement of the Captain's and First Officer's seats. An uncommanded fore or aft seat movement during a critical part of a flight, such as takeoff or landing, could cause a flight control obstruction or unintended flight control input, which could result in the loss of the ability to control the airplane. \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\nSupportive Comments \n\n\n\tVirgin Atlantic Airways and commenters Zhangyi Ye and Sunita Kavthekar expressed their support for the NPRM. \n\nRequest To Clarify Maintenance Log Review Requirement \n\n\n\tLufthansa Airlines (Lufthansa) stated that it is not possible for its mechanics to do a maintenance log review on wing using the procedures specified in Part A.1.c. of Ipeco ServiceBulletin 258-25- 14, Issue 4, dated January 29, 2018. \n\tThe FAA infers that the commenter is referring to the concurrent requirements specified in Boeing Special Attention Service Bulletin 747-25-3653, Revision 1, dated October 19, 2018, as required by paragraph (g) of this AD. \n\tThe FAA offers the following clarification: The concurrent \n\n((Page 67855)) \n\nrequirement in Ipeco Service Bulletin 258-25-14, Issue 4, dated January 29, 2018, contains Note 4, which specifies: ''Part A--Inspection for the limit switch and the actuator assembly inspections can be accomplished on the aircraft or on a test fixture.'' Part A--Inspection requires checks of maintenance logs. Maintenance log reviews are completed off-wing, typically where maintenance logs are kept. The on- aircraft, or on-test fixture activity described in Note 4, refers to the physical inspection of parts, which might be required, for example, to determine a part number, a serial number, or a condition. Therefore, the AD hasnot been changed in this regard. \n\nRequest To Clarify Certain Corrective Actions \n\n\n\tLufthansa stated that Boeing Special Attention Service Bulletin 747-25-3653, Revision 1, dated October 19, 2018, identified as a source of service information for performing certain actions in the proposed AD, does not provide a permanent and acceptable level of safety by including a redesign of the horizontal actuator (including the shaft), which is required to withstand and limit maximum loads to the horizontal output shaft to prevent failure at any phase of seat operation. \n\tLufthansa added that this could be achieved by decoupling the shaft when the maximum force is exceeded, or by a shutdown of the electronics when the voltage is too high. Lufthansa added that further inspections at the intervals specified in the service information are not considered effective, and conditions leading to horizontal actuator shaft failures can occur at any time in between these inspections. Therefore, a moreeffective solution would be a crew procedure. Lufthansa concluded that it expected a terminating action for modified/ compliant airplanes (e.g., mandatory maintenance documentation amendments). \n\tThe FAA offers the following clarification. The FAA has identified the unsafe condition in this final rule as an uncommanded fore or aft seat movement during a critical phase of flight, such as takeoff or landing, that could cause a flight control obstruction or unintended flight control input, which could result in the loss of the ability to control the airplane. \n\tThe FAA does not concur with the commenter's statement that inspections at intervals are not effective. The FAA considered the safety implications in defining the actions required by this AD and determined the actions address the unsafe condition for all of the airplanes identified in this AD. \n\tIn addition, the terminating action for certain seats (those having part number series 3A258) is identified in paragraph (j) of this AD, which specifies the installation of a serviceable Captain's or First Officer's seat as specified in, and in accordance with, the Accomplishment Instructions of Boeing Special Attention Service Bulletin 747-25-3653, Revision 1, dated October 19, 2018. A serviceable Captain's or First Officer's seat is defined in paragraph 3.A. of the referenced service information (i.e., certain seat part numbers that have an horizontal actuator with Artus part number (P/N) AD8650503 at 'Amendment C' or later, which is the redesigned horizontal actuator that is designed to withstand the limit loads that contribute to the unsafe condition). \n\tAdditionally, as specified in the referenced service information, if the horizontal actuator is not P/N AD8650503 'Amendment C' or later, the operator has the option to install a power-deactivated seat as specified in the appropriate airplane maintenance manual (AMM) procedure (AMM procedure 25-11-01-01), in lieu of the terminating action or until the horizontalactuator can be serviced in accordance with the appropriate service information. This provision removes the unsafe condition in the time between the inspections. \n\tFor seats on which a terminating action is not yet available, the FAA has determined that repetitive checks of the HMS and the option to install a power-deactivated seat adequately address the unsafe condition. Thus, a crew procedure is not needed. However, if the FAA obtains and analyzes additional data that indicates the unsafe condition is not addressed by this AD, The FAA might consider further rulemaking to mandate a terminating action for all seats. The AD has not been changed in this regard. \n\nRequest To Change Applicability to Affected Components \n\n\n\tUnited Parcel Service Co. (UPS) asked that paragraph (g) of the proposed AD be changed to mandate accomplishment of the required actions by using certain Ipeco service bulletins. UPS stated that paragraph (g) would require accomplishment of the actions using BoeingSpecial Attention Service Bulletin 747-25-3653, Revision 1, dated October 19, 2018. UPS noted that for the 3A258-004X and 3A090-00XX seats, other than simple foreign object debris (FOD) inspections, the referenced Boeing service information effectively specifies accomplishment of the inspections and modifications per Ipeco Service Bulletin 258-25-14, Issue 4, dated January 29, 2018; and inspections per Ipeco Service Bulletin 258-25-13, Issue 3, dated November 27, 2017, or per Ipeco Service Bulletin 211-25-06, Issue 2, dated March 21, 2018; and inspections per Ipeco Service Bulletin 211-25-05, Issue 2, dated March 21, 2018. \n\tUPS recommends that paragraph (g) mandate the accomplishment of the applicable Ipeco service bulletin, depending on which seat is installed. \n\tUPS also stated that there are NPRMs that mandate the same Ipeco service information via fleet-specific Boeing service information on Model 757 and 767 airplanes. UPS asked that the proposed AD be applicable to the seatsusing Ipeco service information for compliance, instead of applicable to the airplanes using Boeing service information for compliance. \n\tUPS added that since the seats are interchangeable across several fleets, mandating ADs against those fleets could result in, for example, a specific seat being installed on a Model 747 airplane with records identifying compliance with a Model 767 airplane AD. UPS noted that this could lead to confusion and questions regarding compliance, when there is no notable difference between the two ADs, and the AD mandating a component service bulletin using a fleet service bulletin leaves a compliance trap for the operators. UPS recommends there be two separate ADs for this unsafe condition; one mandating the Ipeco service information, and one mandating the Boeing service information for the on-aircraft checks. UPS added that this would allow operators currently using the Ipeco service information at a shop or during a C-check to take credit for those actions at a component level in lieu of an airplane level. \n\tThe FAA infers that the commenter is asking that the agency use the Ipeco service information instead of the Boeing service information; the FAA does not agree. The Ipeco service information would necessitate a component AD, and a component AD would require operators of all airplanes on which an Ipeco seat is installed to inspect their airplanes for the affected part number. \n\tHowever, the potential unsafe condition has been identified for only those airplanes that are specified in the Boeing service information. An unsafe condition has not been identified for the Ipeco seats identified in this AD that are installed on other aircraft types. Therefore, the FAA has determined that a component AD is not appropriate, which is why this AD addresses Model \n\n((Page 67856)) \n\n747 series airplanes and other AD actions require similar actions on other Boeing airplanes for which the unsafe condition exists. Each AD addresses the unsafecondition that might exist on the airplanes identified in the applicability of each AD. If a seat has been removed from a Model 767 airplane and installed on a Model 747 airplane, the actions required by this AD would still be applicable to that seat even if that seat had previously been shown to be in compliance with a Model 767 airplane AD. \n\tIn addition, changing this airplane AD to a component AD would also require an additional public comment period and would unnecessarily delay issuance of this final rule. Therefore, the AD has not been changed in this regard. \n\nRequest To Expand Applicability \n\n\n\tOne commenter, Arjun C, stated that movement of the Captain's and First Officer's seats during flight could potentially impair the ability to effectively fly the airplane and keep all passengers safe. The commenter pointed out that it might be worth expanding the applicability in the proposed AD to all civilian airplanes flying in U.S. airspace, and noted that simply calling outa single company might be a bit myopic in scope. The commenter concluded that, overall, the proposed AD should be effective if executed properly. \n\tThe FAA does not agree with the request. The unsafe condition defined in this AD affects only airplanes with the seats having Ipeco part numbers identified in the referenced Boeing service information. Expanding the applicability as requested would cause an undue burden on operators with airplanes not subject to the unsafe condition. Therefore, the AD has not been changed in this regard. \n\nRequest To Revise Costs of Compliance Section \n\n\n\tBoeing asked that the ''Costs of Compliance'' section in the NPRM be changed to reflect the ''actual cost'' of all the actions. Boeing stated that the seat identification, inspection, and checks involve only labor and should not include the cost of the actuator. Boeing also noted that the ''Cost on U.S. Operators'' for the inspection should be changed from ''$8,075 per seat'' to ''$85 per seat,'' andfor the checks the cost should be changed from ''$16,150 per seat, per check cycle'' to ''$170 per seat, per check cycle.'' \n\tThe FAA agrees that the costs of the seat identification, inspection, and checks do not include a cost for parts. In addition, the FAA has revised the figures for these actions in the ''Cost on U.S. Operators'' column by providing only the estimated fleet cost without reference to cost per seat. \n\tBoeing asked that the actuator cost for the overhaul or replacement be increased from ''Up to $6,400 per seat'' to ''Up to $16,091 per seat,'' based on information received from the parts manufacturer with the increased parts cost. \n\tThe FAA agrees with the commenter's request to change the parts cost, for the reason provided. The FAA has changed the parts cost for the overhaul or replacement specified in the ''Costs of Compliance'' section accordingly. \n\nConclusion \n\n\n\tThe FAA has 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. 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 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\tThe FAA reviewed Boeing Special Attention Service Bulletin 747-25- 3644, Revision 1, dated July 17, 2018. This service information describes procedures for an inspection to determine the part number, and, if applicable, the serial number of the Captain's and First Officer's seats and applicable on-condition actions. On-condition actions include an inspection of each seat's fore/aft and vertical manual control levers for looseness; moving the adjustment nut, tightening the lock nut, readjusting the control lever, and doing a functional test; and installing a serviceable seat. \n\tThe FAA also reviewed Boeing Special Attention Service Bulletin 747-25-3653, Revision 1, dated October 19, 2018. This service information describes procedures for repetitive horizontal actuator identifications, repetitive checks of the HMS, a detailed inspection of the HMS, and applicable on-condition actions. On-condition actions include clearing the seat tracks of FOD, an overhaul of the HMS, and checks of the HMS. The service information also describes procedures for an optional terminating action for the repetitive checks by installing a serviceable Captain's or First Officer's seat. \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\tThe FAA estimates that this AD affects 95 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 on U.S. \n\tAction Labor cost Parts cost Cost per product operators ---------------------------------------------------------------------------------------------------------------- Horizontal actuator 1 work-hour x $85 per $0 $85, per seat, per Up to $16,150, per \n\tidentification. hour = $85, per seat, identification identification \n\tper identification cycle. cycle \n\tcycle. Detailed inspection, horizontal 1 work-hour x 85 per 0 85, per seat...... Up to 16,150 \n\tmovement system. hour = 85, per seat. Checks, horizontal movement 2 work-hour x 85 per 0 170, per seat, per Up to 32,300, per \n\tsystem. hour = 170, per seat, check cycle. check cycle \n\tper check cycle. Seat inspection (part and 1 work-hour x 85 per 0 85, per seat...... 16,150 \n\tserial number). hour = 85, per seat. ---------------------------------------------------------------------------------------------------------------- \n\n\n\n((Page 67857)) \n\n\n\tThe FAA estimates the following costs to do any necessary on- condition actions that will be required. The FAA has no way of determining the number of aircraft that might need these on-condition actions: \n\n\n\tEstimated Costs of On-Condition Actions * ---------------------------------------------------------------------------------------------------------------- \n\tAction Labor cost Parts cost Cost per product ---------------------------------------------------------------------------------------------------------------- Overhaul or replacement, horizontal Up to 15 work-hours x $85 Up to $16,091, per Up to $17,366, per \n\tmovement system. per hour = Up to $1,275, seat. seat \n\tper seat. Inspection of each seat's fore/aft 1 work-hour x 85 per hour = 0..................... 85, per seat \n\tand vertical manual control levers. 85, per seat. Installation of serviceable seats.. 1 work-hour x 85 per hour = 0..................... 85, per seat \n\t85, per seat. Clearing FOD....................... 1 work-hour x 85 per hour = 0..................... 85, per seat \n\t85, per seat. Functional test, adjusted control 1 work-hour x 85 per hour = 0..................... 85, per seat \n\tlever cable. 85, per seat. ---------------------------------------------------------------------------------------------------------------- \n* The estimated cost for tooling to align an affected seat for adjustment of the control lever cable is up to\n\n\t$46,064. \n\n\n\tThe FAA has received no definitive data that would enable the agency to provide cost estimates for the optional terminating action for the on-condition repetitive checks 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\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 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 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.For 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.