[4910-13-P] DEPARTMENT OF TRANSPORTATION Federal Aviation Administration 14 CFR Part 39 [Docket No. FAA-2023-2003; Project Identifier AD-2022-01620-T; Amendment 3922750; AD 2024-10-05] RIN 2120-AA64 Airworthiness Directives; The Boeing Company Airplanes AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule. SUMMARY: The FAA is adopting a new airworthiness directive (AD) for certain The Boeing Company Model 757 airplanes. This AD was prompted by reports of operators finding frequent and severe damage to the blowout vent grilles throughout the lower lobe cargo compartment. This AD requires repetitive detailed inspections of certain decompression panels and pressure equalization valves, as applicable, in the forward and aft lower lobe cargo compartments for damage, and applicable on-condition actions. For certain airplanes, this AD also requires installation of decompression panels with billet grilles. For other certain airplanes, this AD also requires replacement of a certain soft bulkhead with a rigid bulkhead. For certain other airplanes, this AD requires installation of doublers to a certain bulkhead assembly panel. The FAA is issuing this AD to address the unsafe condition on these products. DATES: This AD is effective [INSERT DATE 35 DAYS AFTER DATE OF PUBLICATION IN THE FEDERAL REGISTER]. The Director of the Federal Register approved the incorporation by reference of a certain publication listed in this AD as of [INSERT DATE 35 DAYS AFTER DATE OF PUBLICATION IN THE FEDERAL REGISTER]. ADDRESSES: AD Docket: You may examine the AD docket at regulations.gov under Docket No. FAA2023-2003; or in person at Docket Operations between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains this final rule, any comments received, and other information. The address for Docket Operations is U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue SE, Washington, DC 20590. Material Incorporated by Reference: • For service information, contact Boeing Commercial Airplanes, Attention: Contractual & Data Services (C&DS), 2600 Westminster Blvd., MC 110-SK57, Seal Beach, CA 90740-5600; telephone 562-797-1717; website myboeingfleet.com. • You may view this service information at the FAA, Airworthiness Products Section, Operational Safety Branch, 2200 South 216th St., Des Moines, WA. For information on the availability of this material at the FAA, call 206-231-3195. It is also available at regulations.gov under Docket No. FAA-2023-2003. FOR FURTHER INFORMATION CONTACT: Katherine Venegas, Aviation Safety Engineer, FAA, 2200 South 216th St., Des Moines, WA 98198; telephone: 562-6275353; email: Katherine.Venegas@faa.gov. SUPPLEMENTARY INFORMATION: Background The FAA 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 26, 2023 (88 FR 73543). The NPRM was prompted by reports of operators finding frequent and severe damage to the blowout vent grilles throughout the lower lobe cargo compartment. In the NPRM, the FAA proposed to require repetitive detailed inspections of certain decompression panels and pressure equalization valves, as applicable, in the forward and aft lower lobe cargo compartments for damage, and applicable on-condition actions. For certain airplanes, the FAA proposed to require replacement of a certain soft bulkhead with a rigid bulkhead. For certain other airplanes, the FAA proposed to require installation of doublers to a certain bulkhead assembly panel. The FAA is issuing this AD to address damage to the blowout vent grilles in the forward and aft lower lobe cargo compartments that could lead to latent failure of the decompression panels and pressure equalization valves. This latent failure, in combination with a fire, could make the cargo fire protection, detection, suppression, and containment system ineffective. Also, this latent failure, in combination with rapid decompression of the airplane, could prevent activation of the station (STA) 1640 decompression panels, which could damage the STA 1640 floor beam and cause loss of hydraulic systems components and flight control and damage to the auxiliary power unit (APU) fuel line. This unsafe condition, if not addressed, could result in the inability of the flightcrew to maintain safe flight and landing. Discussion of Final Airworthiness Directive Comments The FAA received a comment from Air Line Pilots Association, International who supported the NPRM without change. The FAA received additional comments from Airlines for America (A4A), Aviation Partners Boeing, Boeing, Delta Air Lines, European Air Transport Leipzig GmbH, FedEx Express, United Airlines, and United Parcel Service (UPS) Airlines. The following presents the comments received on the NPRM and the FAA’s response to each comment. Effect of Winglets on Accomplishment of the Proposed Actions Aviation Partners Boeing stated that the installation of winglets per Supplemental Type Certificate (STC) ST01518SE does not affect the accomplishment of the manufacturer’s service instructions. The FAA agrees with the commenter that STC ST01518SE does not affect the accomplishment of the manufacturer’s service instructions. Therefore, the installation of STC ST01518SE does not affect the ability to accomplish the actions required by this AD. The FAA has not changed this AD in this regard. Request to Correct Typographical Error Boeing requested that the word “grill†be replaced with “grille†throughout the NPRM. Boeing stated grille is consistent with the service information and is the accurate spelling, which means a screen of metal bars or wires placed in front of something as protection or to allow ventilation. The FAA agrees with the change and has revised this final rule accordingly. Request to Clarify the Service History, Unsafe Condition, and Required Actions Boeing requested the NPRM be revised to clarify the service history, unsafe condition, and required actions. Regarding the service history, Boeing clarified that reported damage was not limited to the STA 1640 soft bulkhead lining only; operators reported finding damage on the decompression panels throughout the lower lobe cargo compartment. Boeing also clarified that undetected damage in combination with a cargo compartment fire or rapid depressurization could prevent continued safe flight and landing. Boeing stated that damaged lower lobe decompression panels can diminish the capabilities of the cargo fire protection, detection, suppression, and containment system. Boeing further stated failure of a decompression panel at STA 1640 in combination with a decompression event could cause damage to the bulkhead components including hydraulic systems, flight control functions, and the APU fuel line. Regarding the required actions, Boeing clarified that required actions include, at a minimum, repetitive inspections of lower lobe decompression panels, installation of protective grilles, and for certain airplanes installation of a rigid bulkhead. Boeing is requesting these changes to improve accuracy and consistency with the service information. The FAA agrees to clarify the service history, required actions, and unsafe condition in this final rule: The FAA revised the Summary, Background, and Unsafe Condition paragraphs of this final rule to clarify that operators found frequent and severe damage to the blowout vent grilles throughout the lower lobe cargo compartment. The FAA also revised the Background and Unsafe Condition paragraphs of this final rule to clarify that failure of a STA 1640 decompression panel in combination with rapid decompression of the airplane could also cause damage APU fuel line. Further, the FAA revised the Summary and Related Service Information Under 1 CFR Part 51 paragraphs to clarify that this final rule requires, for certain airplanes, installation of decompression panels with billet grilles on the bulkheads and sidewalls of the forward and aft lower lobe cargo compartments and installation of decompression panels on the ceilings of the forward and aft lower lobe cargo compartments. In the NPRM, the FAA included the cost of installing the decompression panels with the inspection cost. Therefore, the FAA has revised the estimated costs in this final rule by breaking out those costs as separate line items. Request to Exclude Cargo/Freighter Airplanes from the NPRM A4A, FedEx Express, and UPS Airlines requested that cargo/freighter airplanes be excluded from the applicability of the NPRM. The commenters stated cargo operators experience different in-service issues than passenger operators because cargo operators have lower flight hour and flight cycle utilization rates and generally ship smaller and lighter packages in the lower cargo area. The commenters also stated they possess historical data and operational experience that support excluding cargo/freighter airplanes. A4A stated its affected members (Delta Air Lines, FedEx Express, United Airlines, and UPS Airlines) have recorded and documented only insignificant damage to the subject area. Specifically, FedEx reviewed the maintenance data of its Boeing Model 757 fleet over a 15-year period and stated it did not find a single report of a malfunction or damage that would diminish the capabilities of the forward and aft cargo fire protection, detection, suppression, or containment system. UPS Airlines also reviewed its Boeing Model 757 fleet records since 1987 and found 26 grille replacements across all 300 locations. The commenters added that Boeing fleet team digest 757-FTD-25-19003 stated the following: “At this time no incidents have been reported on a latent failure to a decompression panel failing to open or having diminished performance during a rapid decompression event. There have also been no reports of a dislodged decompression panel resulting in diminished functionality of the fire containment, detection or suppression systems.†UPS Airlines stated the risk assessment of the unsafe condition included impacts to fire suppression in the lower cargo components, which does not affect its fleet of Boeing Model 757-200PF airplanes because that airplane model was certified with Class E cargo compartments without fire suppression. For this reason, UPS Airlines concluded that damage to the protective grilles on its freighter airplanes (Group 6 in the service information) will not have the same impact as damage to passenger airplanes. UPS Airlines further stated its freighter airplanes do not have decompression panels at the STA 1640 bulkhead and do not require reinforcement according to the service information. UPS Airlines therefore concluded any risk associated with damage to the STA 1640 floor beam and adjacent flight controls and hydraulic systems would not affect its fleet. The FAA does not agree to exclude cargo/freighter airplanes from the applicability of this AD. The FAA acknowledges cargo operators have different in-service issues than passenger operators, and that cargo operators may have lower utilization rates and different cargo contents. However, the manufacturer evaluated all type design configurations including passenger, freighter, and converted freighter airplanes, and the data available indicated similar damage for containerized cargo and bulk cargo. Sufficient data was not submitted by the commenters to substantiate that excluding cargo airplanes would provide an acceptable level of safety. However, under the provisions of paragraph (i) of this AD, the FAA will consider requests for approval of alternative actions and compliance times if sufficient data are submitted to substantiate that the change would provide an acceptable level of safety. Request to Require Repetitive Inspection Instead of Modification A4A, FedEx Express, and UPS Airlines requested that a repetitive inspection program be implemented for cargo/freighter airplanes instead of the proposed modification (i.e., replacement of protective grilles with new billet grilles) if these airplanes are not excluded from the applicability of the NPRM. A4A also made the same request for passenger-carrying airplanes. United Airlines and Delta Air Lines similarly requested the NPRM be revised to require only initial and repetitive inspections in lieu of modification. As justification, United Airlines stated they have communicated with other affected operators who have indicated similar operating experience of limited or no damage that would indicate decompression valve failure, and their concern that parts will not be available to accomplish the modification within the proposed compliance time. Delta Air Lines stated repetitive inspections in lieu of modification would allow operators the necessary flexibility to obtain the required materials and would continue to ensure the integrity of the decompression panels and valves to address the safety concern. A4A stated that automatic removal of certain existing grilles would be a burden on operators without additional safety benefits. A4A justified a repetitive inspection program over modification because an inspection program would allow all operators to use their existing maintenance programs to identify any potential damage and repair prior to flight. In addition, FedEx Express stated its employees who load/unload cargo perform pre- and post-flight checks of the lower cargo decks, and that any damage found would be repaired prior to flight. FedEx Express also stated, as part of its maintenance program, a visual inspection of the panels is performed every 7 days. FedEx stated that the service information underestimates the number of work-hours required to perform the modification. FedEx also noted the modification would cost over $14.7 million, and that does not include the cost to replace/repair damaged panels. United Airlines stated the modification would cost $1.8 million, which does not include the cost of removing airplanes from service. UPS Airlines objected to the proposed replacement of existing protective grilles with a new billet grille regardless of inspection findings, due to the historical data and documentation of insignificant damage found (as discussed previously). The commenter concluded, if no damage is found during the proposed inspections, then the grilles are structurally and functionally acceptable for operating conditions as certified. In addition, the commenter stated general visual zonal inspections during maintenance program checks, coupled with pre- and post-flight inspections, will adequately address any protective grille damage on an attrition basis. The commenter stated replacement of undamaged grilles is an unnecessary burden on operator resources and provides no operational or safety benefits, especially for the Boeing Model 757-200PF. The FAA does not agree to allow implementation of a repetitive inspection program for cargo- or passenger-carrying airplanes instead of the modification. The FAA considered more frequent and repetitive inspections and evaluated an interval of 750 flight hours. However, the FAA considered this interval to be an unacceptable burden to operators. The FAA determined that those inspections would be intrusive and could cause further damage. The installation of protective grilles with the billet design is necessary to address the unsafe condition. There is not sufficient data to substantiate that repetitive inspections alone would provide an acceptable level of safety. However, under the provisions of paragraph (i) of this AD, the FAA will consider requests for approval of alternative actions and compliance times if sufficient data are submitted to substantiate that the change would provide an acceptable level of safety. Regarding the comments on the costs, the FAA acknowledges the commenters’ concerns about the cost of the modification. The manufacturer provided its best estimate of the number of work hours necessary to do the required actions. Additionally, the FAA notes that the cost analysis in AD rulemaking actions typically includes only the costs associated with complying with the AD, which does not include indirect or incidental costs such as down-time and loss of revenue or the time necessary for planning or other administrative actions. Those incidental or indirect costs might vary significantly among operators. Request to Extend the Compliance Time for Passenger Airplanes A4A requested the NPRM be revised to extend the compliance time for the initial inspection of the decompression panels and modification to 36-48 months for passengercarrying airplanes if the FAA finds a repetitive inspection program unacceptable. United Airlines also requested the compliance time for the modification be extended to 36-48 months. Delta Air Lines requested the compliance time for the initial inspection and modification be extended to within 9,000 flight hours or 36 months after the effective date of the AD. The commenters stated an extension would give the supplier sufficient time to provide the needed parts to operators and allow operators to accomplish the requirements of the proposed AD within their normal maintenance schedule during a heavy maintenance visit, reducing impact to their operations. The FAA does not agree to extend the compliance time for passenger-carrying airplanes. In developing an appropriate compliance time for this action, the FAA considered the recommendations of the manufacturer, the urgency associated with the subject unsafe condition, the availability of required parts, and the practical aspect of accomplishing the required modification within a period of time that corresponds to the normal scheduled maintenance for most affected operators. In consideration of these items, as well as the reports of damage to grilles and panels, the FAA determined that the initial compliance time of 5,425 flight hours or 16 months, whichever occurs first, will ensure an acceptable level of safety. Under the provisions of paragraph (i) of this AD, the FAA will consider requests for approval of an extension of the compliance time if sufficient data are submitted to substantiate that new compliance time would provide an acceptable level of safety. Request to Extend the Compliance Time for Certain Cargo Airplanes UPS Airlines requested the NPRM be revised to extend the compliance time for the initial inspection of the decompression panels to within 9,000 flight hours or 36 months after the effective date of the AD, whichever occurs first, for Boeing Model 757-200PF airplanes (Group 6 in the service information), if the FAA finds a repetitive inspection program unacceptable. The commenter noted that the service information states damage could be caused by repeated loading and unloading of the compartments. The commenter stated cargo operators fly significantly less hours and cycles than passenger aircraft resulting in a proportional decrease in risk associated with damage to the decompression panels, and that the commenter’s affected fleet of Boeing Model 757-200PF airplanes currently averages 943 flight hours and 576 flight cycles per year. Based on this data, the commenter concluded it would take about 69 months for its fleet to reach the proposed initial inspection threshold of 5,425 flight hours, and that the proposed flight hour limits are not proportional to the proposed calendar times. The commenter also noted that the proposed repetitive inspection increases to 9,000 flight hours (114 months based on its fleet utilization) or 26 months, whichever occurs first. The commenter stated that, if a repetitive interval of 26 months is adequate to ensure continued airworthiness, then an initial compliance of 16 months is overly conservative for a fleet that has been operating for more than 35 years without a decompression panel failure because of damage. The FAA agrees to extend the compliance time to within 9,000 flight hours or 36 months after the effective date of this AD, whichever occurs first, for Boeing Model 757-200PF airplanes only. The FAA acknowledges cargo operators have different inservice issues than passenger operators, and cargo operators may have lower utilization rates. Considering that cargo operators fly less hours and cycles than passenger aircraft, the FAA has determined the equivalent flight hour and calendar compliance time can be extended to 9,000 flight hours and 36 months for cargo/freighter operators and still ensure an acceptable level of safety. Therefore, the FAA has added an exception to paragraph (h) of this AD to revise the compliance time to within 9,000 flight hours or within 36 months after the effective date of this AD, whichever occurs first, for Group 6 airplanes. Request to Extend the Compliance Time to 36-48 Months for All Cargo Airplanes A4A, FedEx Express, and European Air Transport Leipzig GmbH, on behalf of DHL Express, requested the NPRM be revised to extend the initial compliance time. FedEx Express requested the compliance time for the initial inspection of the decompression panels and modification be extended to 36-48 months for cargo/freight airplanes if the FAA finds a repetitive inspection program unacceptable. European Air Transport Leipzig GmbH, on behalf of DHL Express, requested the 16-month compliance time be extended to 48 months (and the respective 16,275 flight hours) from the effective of the AD. The commenters stated an extension would give the supplier sufficient time to provide the needed parts to operators and allow operators to accomplish the requirements of the proposed AD within their normal maintenance schedule during a heavy maintenance visit, reducing impact to their operations. The FAA partially agrees. The FAA does not agree to extend the initial compliance time to 48 months for cargo/freight airplanes, but the FAA agrees to extend the compliance time to 36 months. For the reasons discussed previously, the FAA has added exceptions to paragraph (h) of this AD to extend the compliance time to within 9,000 flight hours or within 36 months after the effective date of this AD, whichever occurs first, for Groups 1, 2, and 4 airplanes that have been converted from a passenger to freighter configuration in accordance with VT Mobile Aerospace Engineering (MAE) Inc. STC ST04242AT or STC ST03562AT or Precision Conversions LLC STC ST01529SE, and for Group 6 airplanes. Under the provisions of paragraph (i) of this AD, the FAA will consider requests for approval of an extension of the compliance time if sufficient data are submitted to substantiate that new compliance time would provide an acceptable level of safety. Request to Revise Corrective Action UPS Airlines requested the FAA revise the NPRM to allow operators the option of installing either serviceable protective grilles or billet grilles. UPS Airlines objected to the proposed replacement of existing protective grilles with a new billet grille regardless of inspection findings, due to the historical data and documentation of insignificant damage found (as discussed previously). The commenter concluded, if no damage is found during the proposed inspections, then the grilles are structurally and functionally acceptable for operating conditions as certified. In addition, the commenter stated that the supplier does not have the necessary billet grilles in stock to support inspection of two of its Model 757-200PF airplanes, and the parts supplier has not provided a completion date for the remaining parts. Based on this, the commenter believes supplier cannot adequately support the parts needed for the affected worldwide fleet to meet the proposed compliance time. The FAA does not agree to allow the installation of serviceable protective grilles instead of billet grilles. The FAA acknowledges freighter configuration airplanes are constructed and operated differently than passenger configuration, and that their contents also differ. However, the FAA has determined that the installation of protective grilles with the billet design is necessary to address the unsafe condition. There is not sufficient data to substantiate that the installation of a serviceable protective grille would correct the unsafe condition. The FAA notes that, as discussed previously, the compliance time for cargo operators to accomplish the initial inspections and replacements has been extended in this final rule. Additionally, under the provisions of paragraph (i) of this AD, the FAA will consider requests for approval of alternative actions and compliance times if sufficient data are submitted to substantiate that the change would provide an acceptable level of safety. Request to Add Additional Requirement for Group 3 Airplanes Delta Air Lines requested that an exception be added to the NPRM requiring installation of decompression panels with billet grilles on the bulkheads and sidewall of the forward and aft lower lobe cargo compartments of Group 3 airplanes before further flight. The commenter compared the actions in table 4, condition 8, for Group 3 airplanes and table 6, condition 12, for Group 5 airplanes, and noted table 6 requires installation of decompression panels with billet grilles but table 4 does not. The commenter believes the installation should be required for both airplane groups. The FAA does not agree to revise this final rule. Group 3 airplanes are Boeing Model 757-300 airplanes that already have decompression panels with billet grilles installed per type design. Request to Revise Part Marking Requirement Delta Air Lines requested that an exception be added to the NPRM stating, where certain figures require parts to be marked with the service bulletin number, part marking is only required if not previously marked. The commenter believes the figures that require part marking apply to the initial and repetitive actions. Based on this, the commenter stated the parts would need to be marked every time, even if they were previously marked. The FAA does not agree to revise this final rule. The figures that specify marking the part with the service bulletin number are only listed as a method of compliance for the installation of panels with billet grilles. Those figures are not listed as a method of compliance for the repetitive actions. Conclusion The FAA reviewed the relevant data, considered any comments received, and determined that air safety requires adopting this AD as proposed. Accordingly, the FAA is issuing this AD to address the unsafe condition on these products. Except for minor editorial changes, and any other changes described previously, this AD is adopted as proposed in the NPRM. None of the changes will increase the economic burden on any operator. Related Service Information under 1 CFR Part 51 The FAA reviewed Boeing Alert Requirements Bulletin 757-25A0319 RB, dated March 24, 2023. This service information specifies procedures for repetitive detailed inspections of certain bulkhead (including STA 1640), sidewall, ceiling, and E5 EE rack decompression panels, and pressure equalization valves on certain airplanes, in the forward and aft lower lobe cargo compartments for damage; and applicable on-condition actions. On-condition actions include repair or replacement of any damaged decompression panels or pressure equalization valves. For certain airplanes, the service information specifies procedures for installing decompression panels with billet grilles on the bulkheads and sidewalls of the forward and aft lower lobe cargo compartments and installing decompression panels on the ceilings of the forward and aft lower lobe cargo compartments, as applicable. For other certain airplanes, this service information also specifies procedures for replacing the soft bulkhead at STA 1640 with a rigid bulkhead having decompression panels with billet grilles. For certain other airplanes, this service information specifies procedures for installing doublers to the bulkhead assembly panel at STA 1640. 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. Costs of Compliance The FAA estimates that this AD affects 489 airplanes of U.S. registry. The FAA estimates the following costs to comply with this AD: Estimated costs Parts cost Cost per product Cost on U.S. operators Up to 9 work-hours X $85 per hour = $765 per inspection cycle $0 Up to $765 per inspection cycle Up to $374,085 per inspection cycle Installation of decompression panels (465 airplanes) Up to 12 work-hours X $85 per hour = $1,020 Up to $22,460 Up to $23,480 Up to $10,918,200 Replacement of soft bulkhead (100 airplanes) 10 work-hours X $85 per hour = $850 $108,240 $109,090 $10,909,000 Installation of doublers (7 airplanes) 2 work-hours X $85 per hour = $170 $1,760 $1,930 $13,510 Action Labor cost Detailed Inspection The FAA estimates the following costs to do any necessary repair or replacement based on the results of the required inspection. The agency has no way of determining the number of aircraft that might need this repair or replacement: On-condition costs Action Labor cost Parts cost Cost per product Repair 12 work-hours X $85 per hour = $1,020 $54,120 $55,140 Replacement 12 work-hour X $85 per hour = $1,020 $108,240 $109,260 Authority for this Rulemaking Title 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. The 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. Regulatory Findings 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 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: (1) Is not a “significant regulatory action†under Executive Order 12866, (2) Will not affect intrastate aviation in Alaska, and (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. List of Subjects in 14 CFR Part 39 Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety. The Amendment Accordingly, under the authority delegated to me by the Administrator, the FAA amends 14 CFR part 39 as follows: PART 39 - AIRWORTHINESS DIRECTIVES 1. The authority citation for part 39 continues to read as follows: Authority: 49 U.S.C. 106(g), 40113, 44701. § 39.13 [Amended] 2. The FAA amends § 39.13 by adding the following new airworthiness directive: 2024-10-05 The Boeing Company: Amendment 39-22750; Docket No. FAA-20232003; Project Identifier AD-2022-01620-T. (a) Effective Date This airworthiness directive (AD) is effective [INSERT DATE 35 DAYS AFTER DATE OF PUBLICATION IN THE FEDERAL REGISTER]. (b) Affected ADs None. (c) Applicability This AD applies to The Boeing Company Model 757-200, -200PF, -200CB, and -300 series airplanes, certificated in any category, as identified in Boeing Alert Requirements Bulletin 757-25A0319 RB, dated March 24, 2023. (d) Subject Air Transport Association (ATA) of America Code 25, Equipment/Furnishings. (e) Unsafe Condition This AD was prompted by reports that operators have found, on multiple aircraft, frequent and severe damage to the blowout vent grilles throughout the lower lobe cargo compartment. The FAA is issuing this AD to address damage to the blowout vent grilles in the forward and aft lower lobe cargo compartments that could lead to latent failure of the decompression panels and pressure equalization valves. This latent failure, in combination with a fire, could make the cargo fire protection, detection, suppression, and containment system ineffective. Also, this latent failure, in combination with rapid decompression of the airplane, could prevent activation of the station (STA) 1640 decompression panels, which could damage the STA 1640 floor beam and cause loss of hydraulic systems components and flight control and damage to the auxiliary power unit (APU) fuel line. This unsafe condition, if not addressed, could result in the inability of the flightcrew to maintain safe flight and landing. (f) Compliance Comply with this AD within the compliance times specified, unless already done. (g) Required Actions Except as specified by paragraph (h) of this AD: At the applicable times specified in the “Compliance†paragraph of Boeing Alert Requirements Bulletin 757-25A0319 RB, dated March 24, 2023, do all applicable actions identified in, and in accordance with, the Accomplishment Instructions of Boeing Alert Requirements Bulletin 757-25A0319 RB, dated March 24, 2023. Note 1 to paragraph (g): Guidance for accomplishing the actions required by this AD can be found in Boeing Alert Service Bulletin 757-25A0319, dated March 24, 2023, which is referred to in Boeing Alert Requirements Bulletin 757-25A0319 RB, dated March 24, 2023. (h) Exceptions to Service Information Specifications (1) For all airplanes: Where the Compliance Time columns of the tables in the “Compliance†paragraph of Boeing Alert Requirements Bulletin 757-25A0319 RB, dated March 24, 2023, refer to the original issue date of Requirements Bulletin 757-25A0319 RB, this AD requires using the effective date of this AD. (2) For Groups 1, 2, and 4 airplanes identified in Boeing Alert Requirements Bulletin 757-25A0319 RB, dated March 24, 2023, that have been converted from a passenger to freighter configuration in accordance with VT Mobile Aerospace Engineering (MAE) Inc. Supplemental Type Certificate (STC) ST04242AT or STC ST03562AT or Precision Conversions LLC STC ST01529SE: Where the Compliance Time columns of tables 1, 2, 3, and 5 in the “Compliance†paragraph of Boeing Alert Requirements Bulletin 757-25A0319 RB, dated March 24, 2023, specify “Within 5,425 Flight Hours†and “Within 16 months,†this AD requires replacing that text with “Within 9,000 Flight Hours†and “Within 36 months,†respectively. (3) For Group 6 airplanes identified in Boeing Alert Requirements Bulletin 757-25A0319 RB, dated March 24, 2023: Where the Compliance Time column of table 7 in the “Compliance†paragraph of Boeing Alert Requirements Bulletin 757-25A0319 RB, dated March 24, 2023, specifies “Within 5,425 Flight Hours†and “Within 16 months,†this AD requires replacing that text with “Within 9,000 Flight Hours†and “Within 36 months,†respectively. (i) Alternative Methods of Compliance (AMOCs) (1) The Manager, AIR-520 Continued Operational Safety 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 responsible Flight Standards Office, as appropriate. If sending information directly to the manager of the certification office, send it to the attention of the person identified in paragraph (j)(1) of this AD. Information may be emailed to: AMOC@faa.gov. (2) Before using any approved AMOC, notify your appropriate principal inspector, or lacking a principal inspector, the manager of the responsible Flight Standards Office. (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 Company Organization Designation Authorization (ODA) that has been authorized by the Manager, AIR-520 Continued Operational Safety Branch, FAA, 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. (j) Related Information (1) For more information about this AD, contact Katherine Venegas, Aviation Safety Engineer, FAA, 2200 South 216th St., Des Moines, WA 98198; telephone: 562-627-5353; email: Katherine.Venegas@faa.gov. (2) Service information identified in this AD that is not incorporated by reference is available at the address specified in paragraph (k)(3) of this AD. (k) Material Incorporated by Reference (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. (2) You must use this service information as applicable to do the actions required by this AD, unless the AD specifies otherwise. (i) Boeing Alert Requirements Bulletin 757-25A0319 RB, dated March 24, 2023. (ii) [Reserved] (3) For service information, contact Boeing Commercial Airplanes, Attention: Contractual & Data Services (C&DS), 2600 Westminster Blvd., MC 110-SK57, Seal Beach, CA 90740-5600; telephone 562-797-1717; website myboeingfleet.com. (4) You may view this service information at the FAA, Airworthiness Products Section, Operational Safety Branch, 2200 South 216th St., Des Moines, WA. For information on the availability of this material at the FAA, call 206-231-3195. (5) You may view this material at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, visit www.archives.gov/federal-register/cfr/ibr-locations or email fr.inspection@nara.gov. Issued on May 23, 2024. Suzanne Masterson, Deputy Director, Integrated Certificate Management Division, Aircraft Certification Service. [FR Doc. 2024-13014 Filed: 6/13/2024 8:45 am; Publication Date: 6/14/2024]