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Rule

Airworthiness Directives; The Boeing Company Airplanes

A Rule by the Federal Aviation Administration on 03/12/2026

• 1.

1.

• Document Details Published Content - Document Details Agencies Department of Transportation Federal Aviation Administration Agency/Docket Numbers Docket No. FAA-2025-0618 Project Identifier AD-2024-00637-T Amendment 39-23280 AD 2026-05-07 CFR 14 CFR 39 Document Citation 91 FR 12059 Document Number 2026-04829 Document Type Rule Pages 12059-12064
  (6 pages) Publication Date 03/12/2026 RIN 2120-AA64 Published Content - Document Details

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• Document Details Published Content - Document Details Agencies Department of Transportation Federal Aviation Administration Agency/Docket Numbers Docket No. FAA-2025-0618 Project Identifier AD-2024-00637-T Amendment 39-23280 AD 2026-05-07 CFR 14 CFR 39 Document Citation 91 FR 12059 Document Number 2026-04829 Document Type Rule Pages 12059-12064
  (6 pages) Publication Date 03/12/2026 RIN 2120-AA64 Published Content - Document Details

• Document Dates Published Content - Document Dates Effective Date 2026-04-16 Dates Text This AD is effective April 16, 2026. Published Content - Document Dates

• Table of Contents Enhanced Content - Table of Contents This table of contents is a navigational tool, processed from the
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  • AGENCY:
  • ACTION:
  • SUMMARY:
  • DATES:
  • ADDRESSES:
  • FOR FURTHER INFORMATION CONTACT:
  • SUPPLEMENTARY INFORMATION:
  • Background
  • Discussion of Final Airworthiness Directive
  • Comments
  • Request To Clarify What Prompted the Proposed AD
  • Request To Clarify the Inspection Compliance Time Based on UWL Replacement
  • Request To Correct Paragraph Reference
  • Request To Remove or Revise Requirement for Minimum Thickness of Cap Seals
  • Request To Require Other Service Information for Cap Sealing Requirement
  • Request To Correct Action and Figure Reference
  • Request To Correct Task Name
  • Request To Clarify Procedures for Fastener Installation
  • Request To Correct Shim Part Number
  • Request To Correct Step Reference
  • Request To Revise Open Access Instruction
  • Request To Use Alternative Service Information
  • Request To Provide Fabrication Instructions
  • Request To Clarify the Insurance Cut Note
  • Conclusion
  • Material Incorporated by Reference Under 1 CFR Part 51
  • Costs of Compliance
  • Authority for This Rulemaking
  • Regulatory Findings
  • List of Subjects in 14 CFR Part 39
  • The Amendment
  • PART 39—AIRWORTHINESS DIRECTIVES
  • (a) Effective Date
  • (b) Affected ADs
  • (c) Applicability
  • (d) Subject
  • (e) Unsafe Condition
  • (f) Compliance
  • (g) Required Actions
  • (h) Exceptions to Requirements Bulletin Specifications
  • Figure 1 to Paragraph (h)(4)—Cap Seal Minimum Thickness (All Dimensions in Inches)
  • (i) Alternative Methods of Compliance (AMOCs)
  • (j) Additional Information
  • (k) Material Incorporated by Reference Enhanced Content - Table of Contents

• Related Documents Enhanced Content - Related Documents FederalRegister.gov uses the agency dockets published with the document to display related documents.

| Docket No. FAA-2025-0618
(2 Documents) | | | |
| --- | | | |
| Date | | Action | Title |
| | 2026-03-12 | Final rule. | Airworthiness Directives; The Boeing Company Airplanes |
| | 2025-04-10 | Notice of proposed rulemaking (NPRM). | Airworthiness Directives; The Boeing Company Airplanes |

| Project Identifier AD-2024-00637-T
(2 Documents) | | | |
| --- | | | |
| Date | | Action | Title |
| | 2026-03-12 | Final rule. | Airworthiness Directives; The Boeing Company Airplanes |
| | 2025-04-10 | Notice of proposed rulemaking (NPRM). | Airworthiness Directives; The Boeing Company Airplanes |

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AD-2024-00637-T; The Boeing Company 767-200 Series; 767-300 Series; 767-300F Series; 767-400ER Series airplanes; Inspection of lower underwing longeron fitting

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Department of Transportation

Federal Aviation Administration

1. 14 CFR Part 39
2. [Docket No. FAA-2025-0618; Project Identifier AD-2024-00637-T; Amendment 39-23280; AD 2026-05-07]
3. RIN 2120-AA64 ( printed page 12059) # 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 767-200, -300, -300F, and -400ER series airplanes. This AD was prompted by discovery of a crack at one of the forward lower fastener holes following replacement of a cracked underwing longeron (UWL) fitting. This AD requires performing an open hole high frequency eddy current (HFEC) inspection for cracks of the fastener holes common to the UWL fitting, upper drag splice angle, and lower drag splice angle, and applicable on-condition actions. The FAA is issuing this AD to address the unsafe condition on these products.

DATES:

This AD is effective April 16, 2026.

The Director of the Federal Register approved the incorporation by reference of a certain publication listed in this AD as of April 16, 2026.

ADDRESSES:

AD Docket: You may examine the AD docket at regulations.gov under Docket No. FAA-2025-0618; 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 Boeing material identified in this AD, 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 material 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-2025-0618.

FOR FURTHER INFORMATION CONTACT:

Stefanie Roesli, Aviation Safety Engineer, FAA, 2200 South 216th St., Des Moines, WA 98198; phone: 206-231-3964; email: Stefanie.N.Roesli@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 767-200, -300, -300F, and -400ER series airplanes. The NPRM was published in the Federal Register on April 10, 2025 (90 FR 15318). The NPRM was prompted by discovery of a crack at one of the forward lower fastener holes, outside of the inspection area of Boeing Alert Service Bulletin 767-57A0126, following replacement of a cracked UWL fitting. In the NPRM, the FAA proposed to require performing an HFEC inspection for cracks of the fastener holes common to the UWL fitting, upper drag splice angle, and lower drag splice angle and applicable on-condition actions. The FAA is issuing this AD to ensure that any crack in the forward lower fastener holes at the UWL fitting is found and repaired before reaching a critical length. Such cracking, if not addressed, could result in loss in the primary load path between the fuselage and the wing box, adversely affecting the structural integrity of the airplane.

Discussion of Final Airworthiness Directive

Comments

The FAA received comments from Aviation Partners Boeing and ProTech Aero Services Limited who supported the NPRM without change.

The FAA received additional comments from four commenters, including Boeing, Delta Air Lines (Delta), FedEx Express (FedEx), and United Airlines (United). The following presents the comments received on the NPRM and the FAA's response to each comment.

Request To Clarify What Prompted the Proposed AD

Boeing requested that the FAA revise the first sentence of paragraph (e) of the proposed AD to state that this AD was prompted by discovery of a crack at one of the UWL fitting forward fastener holes, outside of the inspection area of Boeing Alert Service Bulletin 767-57A0126, following replacement of a cracked UWL fitting. The commenter clarified that the crack was discovered on the UWL fitting outside of the inspection area, not outside of the UWL fitting.

The FAA agrees and has revised paragraph (e) accordingly.

Request To Clarify the Inspection Compliance Time Based on UWL Replacement

Boeing requested that the FAA add the following exception to paragraph (h) of the proposed AD: Where the Compliance Time column of the tables in the “Compliance” paragraph of Boeing Alert Requirements Bulletin 767-57A0148 RB, dated October 10, 2024, refers to “after the replacement of the underwing longeron fitting,” the compliance time includes fitting replacement in accordance with Boeing Alert Service Bulletin 767-57A0126, Revision 1, dated November 9, 2011; Revision 2, dated March 12, 2012; Revision 3, dated November 8, 2012; Revision 4, dated April 17, 2014; and Revision 5, dated April 7, 2016 (Revisions 1 through 5 of Boeing Alert Service Bulletin 767-57A0126). The commenter stated this exception clarifies the compliance time for operators who have replaced fittings using Revisions 1 through 5 of Boeing Alert Service Bulletin 767-57A0126. The commenter also stated that the compliance time for the initial open hole HFEC inspection is based on an individual fitting's flight cycles or flight hours, not the airplane's accumulated flight cycles or flight hours, and that replacement of the fitting per Revisions 1 through 5 of Boeing Alert Service Bulletin 767-57A0126 resets the compliance time even though it is not explicitly stated.

The FAA agrees that the compliance time for the initial open hole HFEC inspection in tables 3 and 4 of the Boeing Alert Requirements Bulletin 767-57A0148 RB, dated October 10, 2024, can be calculated from the replacement of the UWL fitting using either Boeing Alert Requirements Bulletin 767-57A0148 RB, dated October 10, 2024, or Revisions 1 through 5 of Boeing Alert Service Bulletin 767-57A0126. Accordingly, the FAA has added a new exception to paragraph (h)(2) of this AD to clarify that compliance time.

Request To Correct Paragraph Reference

Boeing requested that the FAA revise paragraph (h)(2) of the proposed AD to refer to paragraph (i) instead of paragraph (g) of the proposed AD. The commenter stated paragraph (i) of the ( printed page 12060) proposed AD should be referenced for repairs that require alternative methods of compliance (AMOC) approval.

The FAA agrees and has revised paragraph (h)(3) of this AD (corresponding to paragraph (h)(2) of the proposed AD) accordingly.

Request To Remove or Revise Requirement for Minimum Thickness of Cap Seals

Boeing requested that the FAA remove paragraph (h)(3) and figure 1 from the proposed AD. Boeing stated Boeing Alert Requirements Bulletin 767-57A0148 RB, dated October 10, 2024, refers to section 28-11-00 of the 767 Aircraft Maintenance Manual (AMM) (i.e., 767 AMM 28-11-00) for the cap sealing procedure, and the AMM contains the same cap seal minimum thickness specified in figure 1 to paragraph (h)(3) of the proposed AD. Boeing asserted that deleting the proposed requirement would prevent duplication of data and potential questions from operators.

Alternatively, Boeing requested the FAA revise paragraph (h)(3) of the proposed AD to clarify that the requirement applies to in-tank fastener cap sealing only and add a note to refer to 767 AMM 28-11-00 as an acceptable cap sealing procedure for in-tank fasteners. Boeing stated this clarification would prevent potential questions from operators and eliminate conflicting cap sealing requirements for out-of-tank fasteners.

The FAA agrees that the cap sealing requirement of paragraph (h)(4) of this AD (corresponding to paragraph (h)(3) of the proposed AD) does not apply to fasteners outside the fuel tank. Accordingly, the FAA has revised paragraph (h)(4) of this AD to clarify the requirement applies only to fasteners, fastener heads, and fastener threads and collars inside the fuel tank.

The FAA disagrees with Boeing's request to remove the exception or add a note to refer to 767 AMM 28-11-00 as an acceptable procedure for the cap sealing required for in-tank fasteners. Boeing Alert Requirements Bulletin 767-57A0148 RB, dated October 10, 2024, already refers to 767 AMM 28-11-00 as an acceptable procedure, so including such a note in this AD is unnecessary. Further, referencing material as an accepted procedure does not make the actions in the material mandatory. Therefore, the FAA has determined that the exception in paragraph (h)(4) is necessary to ensure the cap sealing procedures are enforceable.

Request To Require Other Service Information for Cap Sealing Requirement

FedEx requested that the FAA remove figure 1 and revise paragraph (h)(3) of the proposed AD to require application of the cap seals to wing tank fasteners internally, in accordance with section 51-20-05 of the 767 Structural Repair Manual (SRM) (i.e., 767 SRM 51-20-05). FedEx stated the exception in paragraph (h)(3) of the proposed AD would result in multiple requirements for cap sealing of fasteners internal to the fuel tank, depending on the task being worked. FedEx also stated that the exception is overly general and should be specific only to cap seals internal to the fuel tank. FedEx noted fasteners that penetrate the 767 fuel tank are subject to Critical Design Configuration Control Limitations (CDCCLs) to ensure the lightning, fault current, and hot short protection requirements of Airworthiness Limitation (AWL) 28-AWL-08 are met. FedEx also noted that AWL 28-AWL-08 specifies no additional FAA Oversight Office approval is required if the repair or alternation is accomplished using 767 SRM procedures.

As stated previously, the FAA agrees that the cap sealing requirement does not apply to fasteners outside the fuel tank and has revised paragraph (h)(4) of this AD accordingly. However, the FAA disagrees with the commenter's request to require that the cap sealing for in-tank fasteners be done in accordance with 767 SRM 51-20-05 because the SRM refers to 767 AMM 28-11-00 for sealing of fuel tank repairs. Referring to 767 AMM 28-11-00 does not make the actions in that material mandatory, and the FAA has determined that the requirements in paragraph (h)(4) of this AD must be accomplished. Further, the FAA disagrees that the exception will result in multiple requirements for cap sealing of fasteners internal to the fuel tank because the 767 AMM 28-11-00 contains the same procedures as the requirements of figure 1 to paragraph (h)(4) of this AD. The FAA has not changed the AD in this regard.

Request To Correct Action and Figure Reference

United requested that the FAA add an exception to paragraph (h) of the proposed AD to correct the instructions and figure reference for Condition 3 (Action 2) in table 1, “Left Side Underwing Longeron Fitting Forward Lower Fastener Holes Inspection” (for Group 1, Configuration 1 and 3) in the Accomplishment Instructions of Boeing Alert Requirements Bulletin 767-57A0148 RB, dated October 10, 2024. The commenter stated that Condition 3 (Action 2) incorrectly specifies performing the HFEC at any hole(s) per figure 3, instead of figure 35. The commenter noted the correct instructions are specified in another condition for the right side underwing longeron fitting inspection. The commenter also stated that Boeing concurred with this change.

The FAA agrees to correct the figure reference and instructions for Condition 3 (Action 2) as requested by the commenter. The FAA notes that the requested change to the instructions is consistent with the “Action” column for Condition 3 (Action 2) of table 1, “Left Side Underwing Longeron Fitting Forward Lower Fastener Holes Inspection,” in the “Compliance” paragraph of Boeing Alert Requirements Bulletin 767-57A0148 RB, dated October 10, 2024. Accordingly, the FAA has added a new exception in paragraph (h)(5) of this AD.

Request To Correct Task Name

Delta requested that the FAA add an exception to paragraph (h) of the proposed AD to correct the task name to “FITTING, UNDERWING LONGERON, RH” in step 5 of figures 6, 8, and 10 of Boeing Alert Requirements Bulletin 767-57A0148 RB, dated October 10, 2024. Delta stated that those figures are for the right-hand UWL longeron, not the left-hand.

The FAA agrees to correct the task name in figures 6, 8, and 10 of Boeing Alert Requirements Bulletin 767-57A0148 RB, dated October 10, 2024, as requested by Delta. Accordingly, the FAA has added a new exception to paragraph (h)(6) of this AD.

Request To Clarify Procedures for Fastener Installation

Boeing requested that the FAA add an exception to paragraph (h) of the proposed AD that requires fasteners installed per Boeing Alert Requirements Bulletin 767-57A0148 RB, dated October 10, 2024, figures 15 through 22, 27, and 28, step 11 (quantity 8) and figures 23 through 26, step 11 (quantity 7) be cap sealed per step 15. Boeing stated Boeing Alert Requirements Bulletin 767-57A0148 RB, dated October 10, 2024, omitted the cap sealing requirements (step 15) for certain fasteners installed per step 11 of the referenced figures. Alternatively, Boeing requested that the FAA revise the proposed AD to mandate Revision 1 of the material, which it plans to issue as soon as possible to add the omitted cap sealing requirements. ( printed page 12061)

The FAA agrees that fasteners installed in accordance with step 11 of the applicable figure in Boeing Alert Requirements Bulletin 767-57A0148 RB, dated October 10, 2024, should be cap sealed in accordance with step 15. Further, fasteners installed in accordance with step 8 of the same figures should also be cap sealed in accordance with step 15. Sealing all of these fasteners is necessary to prevent possible ignition sources within the fuel tank. Accordingly, the FAA has added a new exception in paragraph (h)(7) of this AD. Under the provisions of paragraph (i) of this AD, Boeing may request an AMOC to allow use of Revision 1 to Boeing Alert Requirements Bulletin 767-57A0148 RB after it has been issued.

In its comment, Boeing noted step 11 of figures 23 through 26 involves 7 fasteners. However, the FAA notes that step 11 of those figures in Boeing Alert Requirements Bulletin 767-57A0148 RB, dated October 10, 2024, specifies a quantity of 8 fastener and that sheet 2 of those figures only depicts 7 fastener locations. To address this inconsistency, the FAA has added a new exception to paragraph (h)(8) of this AD to require the installation of 7 fasteners.

Request To Correct Shim Part Number

United requested that the FAA add an exception to paragraph (h) of the proposed AD to correct the part number (P/N) for Shim B in step 9 of figures 23 through 26. The commenter stated that those figures specify removing P/N BACS40R021C037F and installing P/N BACS40R021C032F, but the correct instruction is to install the removed shim P/N BACS40R021C037F. The commenter also stated that Boeing concurred with this change.

The FAA agrees to correct the part number in step 9 (installation) of figures 23 through 26 of Boeing Alert Requirements Bulletin 767-57A0148 RB, dated October 10, 2024. Accordingly, the FAA has added a new exception in paragraph (h)(9) of this AD.

Request To Correct Step Reference

United requested that the FAA add an exception to paragraph (h) of the proposed AD to correct step 2 of figure 34 (sheet 2 of 3) of Boeing Alert Requirements Bulletin 767-57A0148 RB, dated October 10, 2024. The commenter noted that although step 2 is mentioned on sheet 2 of figure 34, there is no circle note 2 on sheet 1 of figure 34. The commenter stated that the fastener installation task in step 2 should be included in step 1, like the fastener installation for the left side UWL fitting in figure 33. The commenter also stated that Boeing concurred with this change.

The FAA agrees that the fastener installation task should be included under step 1, not step 2. Accordingly, the FAA has added a new exception in paragraph (h)(10) of this AD.

Request To Revise Open Access Instruction

Delta requested that the FAA add an exception to paragraph (h) of the proposed AD to revise step 1.a(3) in “Part 1: Open Access” of Boeing Alert Service Bulletin 767-57A0148, dated October 10, 2024. Delta stated that the instruction to make sure the airplane is at operational empty weight (OEW) with or without engines installed should instead specify to make sure the aircraft gross weight and center of gravity, with or without engines installed, are within approved limits for jacking the aircraft, and to refer to aircraft maintenance manual (AMM) 07-11-03 as an accepted procedure. Delta stated that Boeing Alert Service Bulletin 767-57A0148, dated October 10, 2024, does not define OEW, and each airline and manufacturer may have their own definition for OEW based on what they consider to be operational items.

The FAA disagrees with Delta's request. The “Part 1: Open Access” steps are not tagged as required for compliance (RC) and therefore are not included as RC steps in Boeing Alert Requirements Bulletin 767-57A0148 RB, dated October 10, 2024, which is required by this AD. Therefore, no change to this AD is necessary in this regard.

Request To Use Alternative Service Information

Delta requested that the FAA add an exception to paragraph (h) of the proposed AD specifying the removal and installation procedures for the UWL replacement may be done using either Boeing Alert Requirements Bulletin 767-57A0148 RB, dated October 10, 2024, or Boeing Alert Service Bulletin 767-57A0126, Revision 5, dated April 7, 2016 (Revision 5 of Boeing Alert Service Bulletin 767-57A0126). Delta stated Revision 5 of Boeing Alert Service Bulletin 767-57A0126 is mandated by AD 2012-15-12, Amendment 39-17141 (77 FR 46932, August 7, 2012) (AD 2012-15-12). Delta also stated, if replacement of the UWL is required, the removal and installation procedures in both bulletins are required for compliance. Delta noted figures 5, 6, 9, and 10 of Boeing Alert Requirements Bulletin 767-57A0148 RB, dated October 10, 2024, contain removal instructions for the UWL fitting, inspections for an open hole HFEC inspection of the tension bolt hole, and a surface HFEC of the front spar lower chord, while figures 3, 4, 5, 6 in Revision 5 of Boeing Alert Service Bulletin 767-57A0126 contain instructions for the same actions. Delta also noted figures 15, 16, 23, and 24 of Boeing Alert Requirements Bulletin 767-57A0148 RB, dated October 10, 2024, contain installation instructions for the UWL fitting, while figures 7, 8, 9, 10 contain instructions for the same action.

The FAA disagrees with allowing use of alternative service information to accomplish this AD. AD 2012-15-12 does not affect accomplishment of this AD. If cracks are found while accomplishing an inspection required by this AD, the corrective actions must be accomplished according to this AD. The required actions of each AD are standalone because they address different unsafe conditions; one is for an inspection on the forward lower fastener holes where the underwing longeron fitting attaches to two drag splice angles, and the other is for an inspection of the underwing longeron fitting itself. The two ADs are only similar in the on-condition actions of the two inspections. The FAA has not changed this AD in this regard.

Request To Provide Fabrication Instructions

Delta requested that the FAA add an exception to paragraph (h) of the proposed AD to state the fabrication instructions (materials, protective coatings, etc.) for fabricating shims. Delta noted step 1, More Data note (a) in figures 1 and 2 of Boeing Alert Service Bulletin 767-57A0148, dated October 10, 2024, specifies if shims are installed in the joint, ensure they are kept in place during fastener removal, or are removed and retained for re-installation. Alternatively, the thickness can be measured to fabricate replacements. Due to this note, Delta asserted the fabrication instructions for shims should be clearly stated in the proposed AD.

The FAA disagrees with Delta's request. Figures 1 and 2 of Boeing Alert Service Bulletin 767-57A0148, dated October 10, 2024, are not tagged as RC and therefore are not included as RC steps in Boeing Alert Requirements Bulletin 767-57A0148 RB, dated October 10, 2024, that is required by this AD. Therefore, no change to this AD is necessary in this regard. ( printed page 12062)

Request To Clarify the Insurance Cut Note

Delta requested that the FAA add an exception to paragraph (h) of the proposed AD to clarify step 1, More Data note (b) in figures 3 and 4 of Boeing Alert Requirements Bulletin 767-57A0148 RB, dated October 10, 2024, as a precaution. Delta stated that note should be a caution note because it specifies not to perform an insurance cut after the hole is confirmed crack-free by the HFEC inspection, but step 1 and More Data notes (a) and (b) do not specify to perform an insurance cut.

The FAA disagrees with Delta's request. More Data note (a) specifies doing the HFEC inspection in accordance with the Boeing 767 Non-Destructive Testing (NDT) Manual, which includes notes to perform insurance cuts after the inspection, to show the crack is fully removed. More Data note (b) is a directive to not perform those insurance cuts. Therefore, no change to this AD is necessary in this regard.

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.

Material Incorporated by Reference Under 1 CFR Part 51

The FAA reviewed Boeing Alert Requirements Bulletin 767-57A0148 RB, dated October 10, 2024. This material specifies procedures for performing an open hole HFEC inspection for cracks of the fastener holes common to the UWL fitting, upper drag splice angle, and lower drag splice angle, and applicable on-condition actions. On-condition actions include crack repair (e.g., hole oversize repair), an open hole HFEC inspection of the fitting and angles for any crack at hole oversize repair locations, an open hole HFEC inspection of the entire fastener stack-up common to the tension bolt hole and a surface HFEC inspection of the front spar lower chord for any crack, replacement of the underwing longeron fitting with new underwing longeron fitting, underwing longeron fitting hole repair, tension bolt fastener stack-up repair, front spar lower chord repair, and subsequent repetitive open hole HFEC inspections for cracks of the fastener holes common to the UWL fitting, upper drag splice angle, and lower drag splice angle.

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.

Costs of Compliance

The FAA estimates that this AD affects 600 airplanes of U.S. registry. The FAA estimates the following costs to comply with this AD:

| Action | Labor cost | Parts cost | Cost per
product | Cost on U.S.
operators |
| --- | --- | --- | --- | --- |
| HFEC inspection of fastener holes | 170 work-hours × $85 per hour = $14,450 | $0 | $14,450 | $8,670,000 |
The FAA estimates the following costs to do any necessary on-condition actions that would be required based on the results of the inspection. The agency has no way of determining the number of aircraft that might need these repairs:

| Action | Labor cost | Parts cost | Cost per
product |
| --- | --- | --- | --- |
| Replacement | 19 work-hours × $85 per hour = $1,615 | $15,270 | $16,885. |
| Inspections of the fitting and angles, the entire fastener stack-up common to the tension bolt hole, and the front spar lower chord for any crack | Up to 6 work-hours × $85 = Up to $510 | $0 | Up to $510. |
| Repetitive HFEC inspection of fastener holes | 170 work-hours × $85 per hour = $14,450 | $0 | $14,450. |
| * The FAA has received no definitive data on which to base the cost estimates for time and work for the repairs specified in this AD, as the work necessary is variable. | | | |

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.

( printed page 12063)

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:

2026-05-07 The Boeing Company: Amendment 39-23280; Docket No. FAA-2025-0618; Project Identifier AD-2024-00637-T.

(a) Effective Date

This airworthiness directive (AD) is effective April 16, 2026.

(b) Affected ADs

None.

(c) Applicability

This AD applies to The Boeing Company Model 767-200, -300, -300F, and -400ER series airplanes, certificated in any category, as identified in Boeing Alert Requirements Bulletin 767-57A0148 RB, dated October 10, 2024.

(d) Subject

Air Transport Association (ATA) of America Code 57, Wings.

(e) Unsafe Condition

This AD was prompted by discovery of a crack at one of the underwing longeron (UWL) fitting forward fastener holes, outside of the inspection area of Boeing Alert Service Bulletin 767-57A0126, following replacement of a cracked UWL fitting. The FAA is issuing this AD to ensure that any crack in the forward lower fastener holes at the UWL fitting is found and repaired before reaching a critical length. Such cracking, if not addressed, could result in loss in the primary load path between the fuselage and the wing box, adversely affecting the structural integrity of the airplane.

(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 767-57A0148 RB, dated October 10, 2024, do all applicable actions identified in, and in accordance with, the Accomplishment Instructions of Boeing Alert Requirements Bulletin 767-57A0148 RB, dated October 10, 2024.

Note 1 to paragraph (g): Guidance for accomplishing the actions required by this AD can be found in Boeing Alert Service Bulletin 767-57A0148, dated October 10, 2024, which is referred to in Boeing Alert Requirements Bulletin 767-57A0148 RB, dated October 10, 2024.

(h) Exceptions to Requirements Bulletin Specifications

(1) Where the Compliance Time column of the tables in the “Compliance” paragraph of Boeing Alert Requirements Bulletin 767-57A0148 RB, dated October 10, 2024, refers to the original issue date of Requirements Bulletin 767-57A0148 RB, this AD requires using the effective date of this AD.

(2) Where the Compliance Time column of tables 3 and 4 in the “Compliance” paragraph of Boeing Alert Requirements Bulletin 767-57A0148 RB, dated October 10, 2024, specifies a compliance time of within 22,000 flight cycles or 80,000 flight hours after the replacement of the underwing longeron fitting, whichever occurs first, this AD requires that the compliance time be calculated from when replacement of the underwing longeron fitting was done using Boeing Alert Requirements Bulletin 767-57A0148 RB, dated October 10, 2024; or Boeing Alert Service Bulletin 767-57A0126, Revision 1, dated November 9, 2011; Revision 2, dated March 12, 2012; Revision 3, dated November 8, 2012; Revision 4, dated April 17, 2014; or Revision 5, dated April 7, 2016.

(3) Where Boeing Alert Requirements Bulletin 767-57A0148 RB, dated October 10, 2024, specifies contacting Boeing for repair instructions, this AD requires doing the repair using a method approved in accordance with the procedures specified in paragraph (i) of this AD.

(4) During application of any cap seal to a fastener, fastener head, and fastener threads and collars inside the tank, as required by this AD, the cap seal must be applied with a thickness equal to or greater than the dimensions specified in figure 1 to paragraph (h)(4) of this AD.

Figure 1 to Paragraph (h)(4)—Cap Seal Minimum Thickness (All Dimensions in Inches)

( printed page 12064)

(5) Where Condition 3 (Action 2) of table 1 of the “Work Instructions” paragraph of Boeing Alert Requirements Bulletin 767-57A0148 RB, dated October 10, 2024, specifies to repeat the open hole high frequency eddy current (HFEC) inspection at any hole(s) using “figure 3” as the method of compliance, this AD requires, at oversize hole repair location(s), doing an open hole HFEC inspection of the fitting and the angles for any crack using “figure 35” as the method of compliance.

(6) Where the “Action” column of step 5 of figures 6, 8, and 10 of Boeing Alert Requirements Bulletin 767-57A0148 RB, dated October 10, 2024, specifies “FITTING, UNDERWING LONGERON, LH”, this AD requires replacing that text with “FITTING, UNDERWING LONGERON, RH”.

(7) Where step 15 of figures 15 through 28 of Boeing Alert Requirements Bulletin 767-57A0148 RB, dated October 10, 2024, specifies cap sealing fasteners (i.e., applying cap seal to wing tank fasteners internally with BMS 5-45), this AD requires cap sealing all fasteners installed in accordance with steps 8 and 11 of the applicable figure in Boeing Alert Requirements Bulletin 767-57A0148 RB, dated October 10, 2024.

(8) Where step 11 of figures 23 through 26 of Boeing Alert Requirements Bulletin 767-57A0148 RB, dated October 10, 2024, specifies installing a quantity of 8 fasteners, this AD requires installing 7 fasteners.

(9) Where the “Identification” column of step 9 of figures 23 through 26 of Boeing Alert Requirements Bulletin 767-57A0148 RB, dated October 10, 2024, specifies to install BACS40R021C032F, this AD requires installing BACS40R021C037F.

(10) Where the “Step” column of figure 34 of Boeing Alert Requirements Bulletin 767-57A0148 RB, dated October 10, 2024, refers to step 2, this AD requires reidentifying step 2 as an additional step 1 task.

(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 Continued Operational Safety Branch, send it to the attention of the person identified in paragraph (j)(1) of this AD. Information may be emailed to: AMOC@faa.gov. Before using any approved AMOC, notify your appropriate principal inspector, or lacking a principal inspector, the manager of the responsible Flight Standards Office.

(2) 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) Additional Information

(1) For more information about this AD, contact Stefanie Roesli, Aviation Safety Engineer, FAA, 2200 South 216th St., Des Moines, WA 98198; phone: 206-231-3964; email: Stefanie.N.Roesli@faa.gov.

(2) Material identified in this AD that is not incorporated by reference is available at the address specified in paragraph (k)(3) this AD.

(k) Material Incorporated by Reference

(1) The Director of the Federal Register approved the incorporation by reference of the material listed in this paragraph under 5 U.S.C. 552(a) and 1 CFR part 51.

(2) You must use this material as applicable to do the actions required by this AD, unless the AD specifies otherwise.

(i) Boeing Alert Requirements Bulletin 767-57A0148 RB, dated October 10, 2024.

(ii) [Reserved]

(3) For Boeing material identified in this AD, 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 material 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 March 4, 2026.

Lona C. Saccomando,

Acting Deputy Director, Integrated Certificate Management Division, Aircraft Certification Service.

[FR Doc. 2026-04829 Filed 3-11-26; 8:45 am]

BILLING CODE 4910-13-P

Published Document: 2026-04829 (91 FR 12059)