SUPPLEMENTARY INFORMATION:

Background

The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to supersede AD 2019-20-07, Amendment 39-19760 (84 FR 54765, October 11, 2019) (AD 2019-20-07). AD 2019-20-07 applied to all The Boeing Company Model 787-8, 787-9, and 787-10 airplanes. The NPRM was published in the Federal Register on March 18, 2026 (91 FR 12942). The NPRM was prompted by the manufacturer developing further actions to address the unsafe condition. In the NPRM, the FAA proposed to continue to require all requirements of AD 2019-20-07. The NPRM also proposed to require replacing the LE outboard GRA with a LEOLA at leading edge OB slat locations and revising the existing maintenance or inspection program, as applicable, to incorporate a new CMR. The NPRM also proposed to remove airplanes from the applicability. The FAA is issuing this AD to address a potential condition in which the LE OB slat system could be out of position without flight deck annunciation. The unsafe condition, if not addressed, could result in insufficient lift, resulting in inability to maintain continued safe flight and landing.

Discussion of Final Airworthiness Directive

Comments

The FAA received comments from the Air Line Pilots Association, International (ALPA) and United Airlines who supported the NPRM without change.

The FAA received additional comments from Boeing. The following presents the comments received on the NPRM and the FAA's response to each comment.

Request To Clarify That the New Requirements Terminate AD 2019-20-07

Boeing requested a revision to the Summary section of the proposed AD to specify that the new proposed actions would terminate the requirements of AD 2019-20-07.

The FAA agrees and has revised the Summary section of this AD accordingly.

Request To Clarify Timing of Flap Retraction Prohibition

Boeing requested a revision to the Summary and Background sections and the heading to paragraph (i) of the proposed AD to clarify that flap retraction is prohibited under icing conditions “after landing.”

The FAA agrees that the AFM provision prohibits flap retraction under icing conditions after landing and has revised the Summary section accordingly. However, no other changes to this AD are necessary because the ( printed page 64260) description of the prohibition is not restated in the Background section of this AD and because the title of the prohibition in figure 1 to paragraph (i) of this AD already states “Flap Operation After Landing.”

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 B787-81205-SB270055-00 RB, Issue 002, dated November 25, 2024. This material specifies procedures for replacing the LE outboard GRA with a LEOLA at leading edge slat 2 and slat 11 outboard locations and revising the operator's maintenance program to incorporate CMR document item 27-CMR-14, “Functionally check the Leading Edge Power Drive Unit Half System Torque Brake.”

This AD also requires Boeing Alert Requirements Bulletin B787-81205-SB270051-00 RB, Issue 001, dated July 5, 2019, which the Director of the Federal Register approved for incorporation by reference as of October 11, 2019 (84 FR 54765, October 11, 2019).

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

The FAA estimates the average total cost per operator for the retained revision of the existing maintenance or inspection from AD 2019-20-17 to be $7,650 (90 work-hours × $85 per work-hour).

The FAA has determined that the new revision of the existing maintenance or inspection program takes an average of 90 work-hours per operator, although the agency recognizes that this number may vary from operator to operator. Since operators incorporate maintenance or inspection program changes for their affected fleet(s), the FAA has determined that a per-operator estimate is more accurate than a per-airplane estimate. Therefore, the agency estimates the average total cost per operator to be $7,650 (90 work-hours × $85 per work-hour).

The FAA has included all known costs in its cost estimate. According to the manufacturer, however, some or all of the costs of this AD may be covered under warranty, thereby reducing the cost impact on affected operators.

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.

The Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA amends 14 CFR part 39 as follows:

2026-20-10 The Boeing Company: Amendment 39-23483; Docket No. FAA-2026-2712; Project Identifier AD-2025-00931-T. ( printed page 64261)

(a) Effective Date

This airworthiness directive (AD) is effective November 12, 2026.

(b) Affected ADs

This AD replaces AD 2019-20-07, Amendment 39-19760 (84 FR 54765, October 11, 2019) (AD 2019-20-07).

(c) Applicability

This AD applies to The Boeing Company Model 787-8, 787-9, and 787-10 airplanes, certificated in any category, as identified in Boeing Alert Requirements Bulletin B787-81205-SB270055-00 RB, Issue 002, dated November 25, 2024.

(d) Subject

Air Transport Association (ATA) of America Code 27, Flight Controls.

(e) Unsafe Condition

This AD was prompted by a determination that the leading edge (LE) outboard (OB) slat system could be out of position without flight deck annunciation. The FAA is issuing this AD to address a potential condition in which the LE OB slat system could be out of position without flight deck annunciation. The unsafe condition, if not addressed, could result in insufficient lift, resulting in inability to maintain continued safe flight and landing.

(f) Compliance

Comply with this AD within the compliance times specified, unless already done.

(g) Retained Required Actions, With No Changes

This paragraph restates the requirements of paragraph (g) of AD 2019-20-07, with no changes. Except as specified by paragraph (h) of this AD: At the applicable times specified in the “Compliance” paragraph of Boeing Alert Requirements Bulletin B787-81205-SB270051-00 RB, Issue 001, dated July 5, 2019, do all applicable actions identified in, and in accordance with, the Accomplishment Instructions of Boeing Alert Requirements Bulletin B787-81205-SB270051-00 RB, Issue 001, dated July 5, 2019.

Note 1 to paragraph (g):

Guidance for accomplishing the actions required by this AD can be found in Boeing Alert Service Bulletin B787-81205-SB270051-00, Issue 001, dated July 5, 2019, which is referred to in Boeing Alert Requirements Bulletin B787-81205-SB270051-00 RB, Issue 001, dated July 5, 2019.

(h) Retained Exception to Service Information Specifications, With No Changes

This paragraph restates the requirements of paragraph (h) of AD 2019-20-07, with no changes. For purposes of determining compliance with the requirements of this AD: Where Boeing Alert Requirements Bulletin B787-81205-SB270051-00 RB, Issue 001, dated July 5, 2019, uses the phrase “the Issue 001 date of Requirements Bulletin B787-81205-SB270051-00 RB,” this AD requires using “October 11, 2019” (the effective date of AD 2019-20-07).

(i) Retained Airplane Flight Manual (AFM) Revision To Prohibit Flap Retraction Under Icing Conditions, With No Changes

This paragraph restates the requirements of paragraph (i) of AD 2019-20-07, with no changes. Within 60 days after October 11, 2019 (the effective date of AD 2019-20-07), revise the Limitations Section of the existing AFM to include the information in figure 1 to paragraph (i) of this AD. This may be done by inserting a copy of figure 1 to paragraph (i) of this AD into the Limitations Section of the existing AFM.

(j) Retained Maintenance or Inspection Program Revision To Incorporate a New Operation Check, With No Changes

This paragraph restates the requirements of paragraph (j) of AD 2019-20-07, with no changes. Within 60 days after October 11, 2019 (the effective date of AD 2019-20-07), revise the existing maintenance or inspection program, as applicable, to incorporate the information specified in figure 2 to paragraph (j) of this AD. This may be done by inserting a copy of figure 2 to paragraph (j) of this AD into the existing maintenance or inspection program.

( printed page 64262)

( printed page 64263)

( printed page 64264)

( printed page 64265)

( printed page 64266)

(k) Retained No Alternative Actions or Intervals, With No Changes

This paragraph restates the requirements of paragraph (k) of AD 2019-20-07, with no changes. After the existing maintenance or inspection program has been revised as required by paragraph (j) of this AD, no alternative actions ( e.g., inspections) or intervals may be used unless the actions or intervals are approved as an alternative method of compliance (AMOC) in accordance with the procedures specified in paragraph (p) of this AD.

(l) New Required Actions

Except as specified by paragraph (i) of this AD: At the applicable times specified in the “Compliance” paragraph of Boeing Alert Requirements Bulletin B787-81205-SB270055-00 RB, Issue 002, dated November 25, 2024, do all applicable actions identified in, and in accordance with, the ( printed page 64267) Accomplishment Instructions of Boeing Alert Requirements Bulletin B787-81205-SB270055-00 RB, Issue 002, dated November 25, 2024.

Note 2 to paragraph (l):

Guidance for accomplishing the actions required by this AD can be found in Boeing Alert Service Bulletin B787-81205-SB270055-00, Issue 002, dated November 25, 2024, which is referred to in Boeing Alert Requirements Bulletin B787-81205-SB270055-00 RB, Issue 002, dated November 25, 2024.

(m) Terminating Action

Accomplishing the actions required by paragraph (l) of this AD terminates the requirements of paragraphs (g), (i), and (j) of this AD for that airplane. After all affected airplanes in an operator's fleet have complied with paragraph (l) of this AD, the AFM revision required by paragraph (i) of this AD may be removed and the maintenance or inspection program revision required by paragraph (j) of this AD may be removed.

(n) Exceptions to Requirements Bulletin Specifications

Where the Compliance Time column of the tables in the “Compliance” paragraph of Boeing Alert Requirements Bulletin B787-81205-SB270055-00 RB, Issue 002, dated November 25, 2024, refers to the Issue 001 date of Requirements Bulletin B787-81205-SB270055-00 RB, this AD requires using the effective date of this AD.

(o) Credit for Previous Actions

This paragraph provides credit for the actions specified in paragraph (l) of this AD, if those actions were performed before the effective date of this AD using Boeing Alert Requirements Bulletin B787-81205-SB270055-00 RB, Issue 001, dated December 12, 2023.

(p) 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 (q)(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.

(3) AMOCs approved for AD 2019-20-07 are approved as AMOCs for the corresponding provisions of paragraphs (g), (i), and (j) of this AD.

(q) Additional Information

(1) For more information about this AD, contact Emanuel Chaves Torres, Aviation Safety Engineer, FAA, 2200 South 216th St., Des Moines, WA 98198; phone: 562-627-5350; email: emanuel.chaves.torres@faa.gov.

(2) Material identified in this AD that is not incorporated by reference is available at the address specified in paragraph (r)(5) of this AD.

(r) Material Incorporated by Reference

(1) The Director of the Federal Register approved the incorporation by reference (IBR) 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 this AD specifies otherwise.

(3) The following material was approved for IBR on November 12, 2026.

(i) Boeing Alert Requirements Bulletin B787-81205-SB270055-00 RB, Issue 002, dated November 25, 2024.

(ii) [Reserved]

(4) The following material was approved for IBR on October 11, 2019 (84 FR 54765, October 11, 2019).

(i) Boeing Alert Requirements Bulletin B787-81205-SB270051-00 RB, Issue 001, dated July 5, 2019.

(ii) [Reserved]

(5) 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.

(6) 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.

(7) 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.

91 FR 64259