AD 2026-20-14

This AD is effective November 23, 2026.

The Director of the Federal Register approved the incorporation by reference of a certain publication listed in this AD as of November 23, 2026.

AD Docket: You may examine the AD docket at regulations.gov under Docket No. FAA-2025-5403; 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-2025-5403.

Raymond Vital, Aviation Safety Engineer, FAA, 2200 South 216th St., Des Moines, WA 98198; phone: 206-231-3521; email: Raymond.J.Vital@faa.gov.

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 737-600, -700, -700C, -800, -900, and -900ER series airplanes. The NPRM was published in the Federal Register on January 9, 2026 (91 FR 931); corrected January 16, 2026 (91 FR 2090). The NPRM was prompted by reports from multiple operators of pitch oscillation events due to excessive horizontal stabilizer freeplay. In the NPRM, the FAA proposed to require measuring the freeplay of the horizontal stabilizer pivot hinges and the jackscrew and applicable on-condition actions. The FAA is issuing this AD to address excessive horizontal stabilizer freeplay. The unsafe condition, if not addressed, could lead to a flutter event, which can result in loss of control of the airplane.

The FAA received comments from five commenters, including the Air Line Pilots Association, International, Boeing, and two individuals who supported the NPRM without change.

The FAA received additional comments from four commenters, including Alaska Airlines, Aviation Partners Boeing (APB), Canadian North, and United Airlines. The following presents the comments received on the NPRM and the FAA's response to each comment.

APB stated that the blended or split scimitar winglets installed per Supplemental Type Certificate (STC) ST00830SE does not affect compliance with the proposed requirements. APB further stated that, for airplanes with the split scimitar winglet (SSW) configuration, an alternative method of compliance (AMOC) might not be able to be obtained from The Boeing Company Organization Designation Authorization (ODA) per paragraph (i)(2) of the proposed AD for either (1) a repair of any worn parts identified as SSW-affected, as a result of proposed inspections, or (2) a deviation from the instructions of the Boeing service information in an SSW-affected area. APB noted that Boeing does not have delegated authority to approve repairs or deviations in areas affected by the SSW configuration, but that operators of airplanes accomplishing a repair of SSW-affected parts or deviation from Boeing service information in an SSW-affected area may obtain an alternative method of compliance (AMOC) according to paragraph (i)(1) of the proposed AD.

The FAA agrees that the installation of STC ST00830SE does not affect the ability to accomplish the actions required by this AD. The FAA has not changed this AD in this regard.

Canadian North requested that the FAA extend the initial inspection threshold from 12 months to 36 months after the original issue date of Boeing Alert Requirements Bulletin 737-55A1104 RB, dated June 12, 2025 (Boeing Alert Requirements Bulletin 737-55A1104 RB), to align it with the repetitive inspection interval. The commenter stated this would also align the initial inspection with the typical heavy maintenance visit, which would allow sufficient time for procurement, planning, and logistical coordination, thereby minimizing the risk of unscheduled downtime and reducing administrative burden.

United Airlines noted the repetitive inspection intervals are the same regardless of the inspection findings and applicable follow-on action, i.e., either keeping the original parts installed or replacing or repairing a worn part. The commenter stated it believes the repetitive inspection intervals for airplanes with newly replaced parts (specifically hinge bearings) should be longer than the intervals for airplanes that have original production parts installed.

The FAA disagrees with extending the initial inspection threshold and the repetitive inspection intervals for airplanes with newly replaced parts. The FAA has determined that the compliance times identified in the required service information will ensure an acceptable level of safety for the fleet. Further, the repetitive inspection intervals were chosen to ensure that excessive freeplay does not exist for either original or new or replaced parts. However, under the provisions of paragraph (i) of this AD, the FAA will consider requests for approval of an extension of a compliance time, if sufficient data are submitted to substantiate that the new compliance time would provide an acceptable level of safety. The FAA has not changed this AD in this regard.

Alaska Airlines requested that the FAA revise paragraph (g) of the proposed AD to allow accomplishment of Actions 1, 2, and 3 of Table 3, Condition 3 of Boeing Alert Requirements Bulletin 737-55A1104 RB as an option to the required actions in Table 3, Condition 2. The commenter stated that Table 3, Condition 2 drives operators to Table 4, Condition 2, which consists of doing an interim freeplay check within 3,100 flight hours or within 6 months after the last freeplay check, and that a second interim freeplay check is required if the measurements of the first interim freeplay check fall under Table 4, Condition 2.1. The commenter stated that this change would allow operators to repair or replace parts to bring the airplane within the Level 1 limits and avoid interim freeplay checks.

The FAA disagrees with providing a deviation to the tables in the “Compliance” paragraph and Accomplishment Instructions of Boeing Alert Requirements Bulletin 737-55A1104 RB. Table 3, Condition 2 and Table 4, Condition 2 do not prohibit accomplishing an inspection earlier than the specified compliance time; therefore, operators may accomplish the interim inspection in Table 4, Condition 2 early, and then perform the repair or replacement as soon as practical within the same maintenance period. A post-repair/replacement inspection is still required to verify freeplay values D1, D2, D3, and H are within the Level 1 limits before the airplane is returned to service. Additionally, under the provisions of paragraph (i) of this AD, the FAA will consider AMOC requests for a deviation to the required actions, provided adequate supporting information is submitted. The FAA has not changed this AD in this regard.

United Airlines requested that the FAA revise the proposed AD to provide credit for inspecting the horizontal stabilizer for free play using Boeing Multi-Operator Message (MOM) MOM-MOM-22-0187-01B(R1), dated May 27, 2022 (Boeing MOM-MOM-22-0187-01B(R1)). The commenter noted that Boeing MOM-MOM-22-0187-01B(R1) states operators are able to obtain credit for performing this inspection once the eventual service bulletin and the potential AD are released. The commenter also stated it reviewed Boeing MOM-MOM-22-0187-01B(R1) and Boeing Alert Requirements Bulletin 737-55A1104 RB and confirmed they contain identical work instructions for the freeplay inspection.

The FAA disagrees because it is not necessary to provide credit in this AD. Airplanes on which accepted freeplay measurement procedures were accomplished using Boeing MOM-MOM-22-0187-01B(R1), or other certain service information, are classified as Group 1, Configuration 1 airplanes. Refer to the note under paragraph 1.A., “Effectivity,” of Boeing Alert Requirements Bulletin 737-55A1104 RB. The work instructions for Group 1, Configuration 1 airplanes already provide some relief for prior accomplishment of the freeplay measurement. The FAA has not changed this AD in this regard.

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, this AD is adopted as proposed in the NPRM. None of the changes will increase the economic burden on any operator.

The FAA reviewed Boeing Alert Requirements Bulletin 737-55A1104 RB, dated June 12, 2025. This material specifies procedures for measuring freeplay of the left and right horizontal stabilizer pivot hinges and the jackscrew to determine freeplay value, and applicable on-condition actions. On-condition actions include determining total horizontal stabilizer freeplay, repeating the freeplay measurement procedure of the horizontal stabilizer pivot hinges and the jackscrew, and replacement or repair of any worn parts.

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.

The FAA estimates that this AD affects 1,987 airplanes of U.S. registry. The FAA estimates the following costs to comply with this AD:

The FAA estimates the following costs to do any necessary replacements 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 replacements:

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.

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.

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

1. The authority citation for part 39 continues to read as follows:

2. The FAA amends § 39.13 by adding the following new airworthiness directive: