Rule2026-21333
Airworthiness Directives; The Boeing Company Airplanes
Primary source
Metadata and text below are from the Federal Register, a public-domain U.S. government work. Always verify the official published version before relying on it for any legal matter.
Published
October 19, 2026
Effective
November 23, 2026
Issuing agencies
Transportation DepartmentFederal Aviation Administration
Abstract
The FAA is adopting a new airworthiness directive (AD) for certain The Boeing Company Model 737-600, -700, -700C, -800, -900, and -900ER series airplanes. This AD was prompted by reports from multiple operators of pitch oscillation events due to excessive horizontal stabilizer freeplay. This AD requires 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 the unsafe condition on these products.
Full Text
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<title>Federal Register, Volume 91 Issue 200 (Monday, October 19, 2026)</title>
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[Federal Register Volume 91, Number 200 (Monday, October 19, 2026)]
[Rules and Regulations]
[Pages 65959-65961]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2026-21333]
[[Page 65959]]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2025-5403; Project Identifier AD-2025-01167-T;
Amendment 39-23487; AD 2026-20-14]
RIN 2120-AA64
Airworthiness Directives; The Boeing Company Airplanes
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final rule.
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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for
certain The Boeing Company Model 737-600, -700, -700C, -800, -900, and
-900ER series airplanes. This AD was prompted by reports from multiple
operators of pitch oscillation events due to excessive horizontal
stabilizer freeplay. This AD requires 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 the unsafe
condition on these products.
DATES: 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.
ADDRESSES:
AD Docket: You may examine the AD docket at <a href="http://regulations.gov">regulations.gov</a> 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:
<bullet> 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 <a href="http://myboeingfleet.com">myboeingfleet.com</a>.
<bullet> 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 <a href="http://regulations.gov">regulations.gov</a> under
Docket No. FAA-2025-5403.
FOR FURTHER INFORMATION CONTACT: Raymond Vital, Aviation Safety
Engineer, FAA, 2200 South 216th St., Des Moines, WA 98198; phone: 206-
231-3521; email: <a href="/cdn-cgi/l/email-protection#0f5d6e766260616b21452159667b6e634f696e6e21686079"><span class="__cf_email__" data-cfemail="a0f2c1d9cdcfcec48eea8ef6c9d4c1cce0c6c1c18ec7cfd6">[email protected]</span></a>.
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 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.
Discussion of Final Airworthiness Directive
Comments
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.
Effect of Winglets on Accomplishment of the Proposed Actions
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.
Request To Extend Certain Compliance Times
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
[[Page 65960]]
of safety. The FAA has not changed this AD in this regard.
Request To Allow a Deviation to Certain Required Actions
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.
Request To Provide Credit for Other Service Information
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.
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, 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 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.
Costs of Compliance
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:
Estimated Costs
----------------------------------------------------------------------------------------------------------------
Cost per Cost on U.S.
Action Labor cost Parts cost product operators
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Freeplay measurement procedure.......... 6 work-hours x $85 per $0 $510 $1,013,370
hour = $510.
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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:
On-Condition Costs
----------------------------------------------------------------------------------------------------------------
Action Labor cost Parts cost Cost per product
----------------------------------------------------------------------------------------------------------------
Repeat freeplay measurement procedure........ 6 work-hours x $85 per hour = $0 $510
$510.
Replacement or repair of worn parts.......... 1 work-hour x $85 per hour = $85 * 0 85
----------------------------------------------------------------------------------------------------------------
* The FAA has received no definitive data on which to base the cost estimate for the worn parts.
[[Page 65961]]
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
0
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701.
Sec. 39.13 [Amended]
0
2. The FAA amends Sec. 39.13 by adding the following new airworthiness
directive:
2026-20-14 The Boeing Company: Amendment 39-23487; Docket No. FAA-
2025-5403; Project Identifier AD-2025-01167-T.
(a) Effective Date
This airworthiness directive (AD) is effective November 23,
2026.
(b) Affected ADs
None.
(c) Applicability
This AD applies to The Boeing Company Model 737-600, -700, -
700C, -800, -900, and -900ER series airplanes, certificated in any
category, as identified in Boeing Alert Requirements Bulletin 737-
55A1104 RB, dated June 12, 2025.
(d) Subject
Air Transport Association (ATA) of America Code 55, Stabilizers.
(e) Unsafe Condition
This AD was prompted by reports from multiple operators of pitch
oscillation events due to excessive horizontal stabilizer freeplay.
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.
(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 737-55A1104 RB, dated June 12, 2025, do
all applicable actions identified in, and in accordance with, the
Accomplishment Instructions of Boeing Alert Requirements Bulletin
737-55A1104 RB, dated June 12, 2025.
Note 1 to paragraph (g): Guidance for accomplishing the actions
required by this AD can be found in Boeing Alert Service Bulletin
737-55A1104, dated June 12, 2025, which is referred to in Boeing
Alert Requirements Bulletin 737-55A1104 RB, dated June 12,2025.
(h) Exception to Requirements Bulletin Specifications
Where the ``Effectivity'' paragraph and the Boeing Recommended
Compliance Time columns of the tables in the ``Compliance''
paragraph of Boeing Alert Requirements Bulletin 737-55A1104 RB,
dated June 12, 2025, refer to the original issue date of the
Requirements Bulletin 737-55A1104 RB, this AD requires using the
effective date of this AD.
(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) of this AD. Information may be emailed to:
<a href="/cdn-cgi/l/email-protection#62232f2d21220403034c050d14"><span class="__cf_email__" data-cfemail="c485898b8784a2a5a5eaa3abb2">[email protected]</span></a>. 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 Raymond Vital,
Aviation Safety Engineer, FAA, 2200 South 216th St., Des Moines, WA
98198; phone: 206-231-3521; email: <a href="/cdn-cgi/l/email-protection#a3f1c2dacecccdc78de98df5cad7c2cfe3c5c2c28dc4ccd5"><span class="__cf_email__" data-cfemail="2c7e4d55414342480266027a45584d406c4a4d4d024b435a">[email protected]</span></a>.
(2) Material 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 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 737-55A1104 RB, dated
June 12, 2025.
(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 <a href="http://myboeingfleet.com">myboeingfleet.com</a>.
(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 <a href="http://www.archives.gov/federal-register/cfr/ibr-locations">www.archives.gov/federal-register/cfr/ibr-locations</a> or email <a href="/cdn-cgi/l/email-protection#462034682f2835362325322f2928062827342768212930"><span class="__cf_email__" data-cfemail="2c4a5e0245425f5c494f584543426c424d5e4d024b435a">[email protected]</span></a>.
Issued on October 9, 2026.
Brian Knaup,
Acting Deputy Director, Integrated Certificate Management Division,
Aircraft Certification Service.
[FR Doc. 2026-21333 Filed 10-16-26; 8:45 am]
BILLING CODE 4910-13-P
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