Rule2026-07484
Special Conditions: Honeywell International Inc., Boeing Model 757-200, 757-200PF, 757-200CB, and 757-300 Airplanes; Non-Rechargeable Lithium Batteries and Battery System Installation
Primary source
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Published
April 16, 2026
Effective
April 16, 2026
Issuing agencies
Transportation DepartmentFederal Aviation Administration
Abstract
These special conditions are issued for the Boeing Company (Boeing) 757 series airplane models 757-200, 757-200PF, 757-200CB, and 757-300. These airplanes, as modified by Honeywell International, Inc. (Honeywell), will have a novel or unusual design feature when compared to the state of technology envisioned in the airworthiness standards for transport-category airplanes. This design feature is for the installation of non-rechargeable lithium batteries in an underwater locator beacon (ULB). The applicable airworthiness regulations do not contain adequate or appropriate safety standards for this design feature. These special conditions contain the additional safety standards that the Administrator considers necessary to establish a level of safety equivalent to that established by the existing airworthiness standards.
Full Text
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<title>Federal Register, Volume 91 Issue 73 (Thursday, April 16, 2026)</title>
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[Federal Register Volume 91, Number 73 (Thursday, April 16, 2026)]
[Rules and Regulations]
[Pages 20319-20321]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2026-07484]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. FAA-2026-3506; Special Conditions No. 25-889-SC]
Special Conditions: Honeywell International Inc., Boeing Model
757-200, 757-200PF, 757-200CB, and 757-300 Airplanes; Non-Rechargeable
Lithium Batteries and Battery System Installation
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final special conditions; request for comments.
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SUMMARY: These special conditions are issued for the Boeing Company
(Boeing) 757 series airplane models 757-200, 757-200PF, 757-200CB, and
757-300. These airplanes, as modified by Honeywell International, Inc.
(Honeywell), will have a novel or unusual design feature when compared
to the state of technology envisioned in the airworthiness standards
for transport-category airplanes. This design feature is for the
installation of non-rechargeable lithium batteries in an underwater
locator beacon (ULB). The applicable airworthiness regulations do not
contain adequate or appropriate safety standards for this design
feature. These special conditions contain the additional safety
standards that the Administrator considers necessary to establish a
level of safety equivalent to that established by the existing
airworthiness standards.
DATES: This action is effective on Honeywell on April 16, 2026. Send
comments on or before June 1, 2026.
ADDRESSES: Send comments identified by Docket No. FAA-2026-3506 using
any of the following methods:
<bullet> Federal eRegulations Portal: Go to <a href="http://www.regulations.gov">www.regulations.gov</a> and
follow the online instructions for sending your comments
electronically.
<bullet> Mail: Send comments to Docket Operations, M-30, U.S.
Department of Transportation (DOT), 1200 New Jersey Avenue SE, Room
W12-140, West Building Ground Floor, Washington, DC 20590-0001.
<bullet> Hand Delivery or Courier: Take comments to Docket
Operations in Room W12-140 of the West Building Ground Floor at 1200
New Jersey Avenue SE, Washington, DC, between 9 a.m. and 5 p.m., Monday
through Friday, except Federal holidays.
<bullet> Fax: Fax comments to Docket Operations at 202-493-2251.
Docket: Background documents or comments received may be read at
<a href="http://www.regulations.gov">www.regulations.gov</a> at any time. Follow the online instructions for
accessing the docket or go to Docket Operations in Room W12-140 of the
West Building Ground Floor at 1200 New Jersey Avenue SE, Washington,
DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal
holidays.
FOR FURTHER INFORMATION CONTACT: Nazih Khaouly, Aircraft Systems, AIR-
626A, Technical Innovation Policy Branch, Policy and Innovation
Division, Aircraft Certification Service, Federal Aviation
Administration, 2200 South 216th Street, Des Moines, Washington 98198;
telephone and fax 206-231-3160; email <a href="/cdn-cgi/l/email-protection#127c73687b7a3c797a737d677e6b527473733c757d64"><span class="__cf_email__" data-cfemail="3a545b4053521451525b554f56437a5c5b5b145d554c">[email protected]</span></a>.
SUPPLEMENTARY INFORMATION: The substance of these special conditions
has been published in the Federal Register for public comment in
several prior instances with no substantive comments received.
Therefore, the FAA finds, pursuant to 14 CFR 11.38(b), that new
comments are unlikely, and notice and comment prior to this publication
are unnecessary.
Privacy
Except for Confidential Business Information (CBI) as described in
the following paragraph, and other information as described in title
14, Code of Federal Regulations (14 CFR) 11.35, the FAA will post all
comments received without change to <a href="http://www.regulations.gov">www.regulations.gov</a>, including any
personal information you provide. The FAA will also post a report
summarizing each substantive verbal contact received about these
special conditions.
Confidential Business Information
Confidential Business Information (CBI) is commercial or financial
information that is both customarily and actually treated as private by
its owner. Under the Freedom of Information Act (FOIA) (5 U.S.C. 552),
CBI is exempt from public disclosure. If your comments responsive to
these special conditions contain commercial or financial information
that is customarily treated as private, that you actually treat as
private, and that is relevant or responsive to these special
conditions, it is important that you clearly designate the submitted
comments as CBI. Please mark each page of your submission containing
CBI as ``PROPIN.'' The FAA will treat such marked submissions as
confidential under the FOIA, and the indicated comments will not be
placed in the public docket of these special conditions. Send
submissions containing CBI to the individual listed in the FOR FURTHER
INFORMATION CONTACT section above. Comments the FAA receives, which are
not specifically designated as CBI, will be placed in the public docket
for these proposed special conditions.
Comments Invited
The FAA invites interested people to take part in this rulemaking
by sending written comments, data, or views. The most helpful comments
reference a specific portion of the special conditions, explain the
reason for any recommended change, and include supporting data.
[[Page 20320]]
The FAA will consider all comments received by the closing date for
comments. The FAA may change these special conditions based on the
comments received.
Background
On January 8, 2026, Honeywell applied for a supplemental type
certificate for the installation of non-rechargeable lithium batteries
in the ULB in the Boeing Model 757-200, 757-200PF, 757-200CB, 757-300
series airplanes. These airplanes, approved under Type Certificate No.
A2NM, are twin engine transport category airplanes. The Boeing Model
757-200, 757-200PF, 757-200CB, 757-300 series airplanes have a maximum
passenger range between 7 and 239 passengers, and a maximum takeoff
weight range between 230,500 and 273,000 pounds, depending on model and
configuration.
Type Certification Basis
Under the provisions of title 14, Code of Federal Regulations (14
CFR) 21.101, Honeywell must show that the Boeing Model 757-200, 757-
200PF, 757-200CB, 757-300 series airplanes, as changed, continue to
meet the applicable provisions of the regulations listed in Type
Certificate No. A2NM or the applicable regulations in effect on the
date of application for the change, except for earlier amendments as
agreed upon by the FAA.
If the Administrator finds that the applicable airworthiness
regulations (e.g., 14 CFR part 25) do not contain adequate or
appropriate safety standards for the Boeing Model 757-200, 757-200PF,
757-200CB, and 757-300 airplanes because of a novel or unusual design
feature, special conditions are prescribed under the provisions of
Sec. 21.16.
Special conditions are initially applicable to the model for which
they are issued. Should the Honeywell apply for a supplemental type
certificate to modify any other model included on the same type
certificate to incorporate the same novel or unusual design feature,
these special conditions would also apply to the other model under
Sec. 21.101.
In addition to the applicable airworthiness regulations and special
conditions, the Boeing Model 757-200, 757-200PF, 757-200CB, 757-300
series airplanes must comply with the exhaust-emission requirements of
14 CFR part 34, and the noise-certification requirements of 14 CFR part
36.
The FAA issues special conditions, as defined in 14 CFR 11.19, in
accordance with Sec. 11.38, and they become part of the type
certification basis under Sec. 21.101.
Novel or Unusual Design Features
The Boeing Model 757-200, 757-200PF, 757-200CB, 757-300 series
airplanes, as modified by Honeywell, will incorporate the following
novel or unusual design feature:The installation of non-rechargeable
lithium batteries in the underwater locator beacon (ULB).
Discussion
The FAA derived the current regulations governing installation of
batteries in transport-category airplanes from Civil Air Regulations
(CAR) 4b.625(d), as part of the recodification of CAR 4b, which
established 14 CFR part 25 in February 1965. This recodification
essentially reworded the CAR 4b battery requirements, which are
currently in Sec. 25.1353(b)(1) through (4). Non-rechargeable lithium
batteries and battery systems are novel and unusual with respect to the
state of technology considered when these requirements were codified.
Non-rechargeable lithium batteries and battery systems introduce higher
energy levels into airplane systems through new chemical compositions
in various battery-cell sizes and construction. Interconnection of
these cells in battery packs introduce failure modes that require
unique design considerations, such as provisions for thermal
management.
In January 2013, two independent events involving rechargeable
lithium-ion batteries revealed unanticipated failure modes. A National
Transportation Safety Board letter to the FAA, dated May 22, 2014,
which is available at <a href="https://www.ntsb.gov">https://www.ntsb.gov</a>, filename A-14-032-036.pdf,
describes these events.
On July 12, 2013, an event involving a non-rechargeable lithium
battery in an ELT installation demonstrated unanticipated failure
modes. The United Kingdom's Air Accidents Investigation Branch Bulletin
S5/2013 \1\ describes this event. These events, involving rechargeable
and non-rechargeable lithium batteries, prompted the FAA to initiate a
broad evaluation of these energy-storage technologies.
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\1\ See Aircraft Accident Report 2/2015--Boeing B787-8, ET-AOP,
12 July 2013 Ground fire at London Heathrow Airport on 12 July 2013.
<a href="http://www.gov">www.gov</a>.uk/aaib-reports/aircraft-accident-report-2-2015-boeing-b787-
8-et-aop-12-july-2013.
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On April 22, 2016, the FAA published special conditions No. 25-612-
SC in the Federal Register (81 FR 23573), applicable to Gulfstream
Aerospace Corporation, for the Model GVI airplane. Those were the first
special conditions the FAA issued for non-rechargeable lithium battery
installations. In that document, the FAA explained its decision to make
those special conditions effective on April 22, 2017, one year after
publication in the Federal Register. In those special conditions, the
FAA stated its intention to apply non-rechargeable lithium battery and
battery system special conditions to design changes on other airplane
makes and models applied for after this same date.
Special condition 1 of these special conditions requires that each
individual cell within a non-rechargeable lithium battery and battery
system be designed to maintain safe temperatures and pressures. Special
condition 2 addresses these same issues but for the entire battery.
Special condition 2 requires the battery be designed to prevent
propagation of a thermal event, such as self-sustained, uncontrollable
increases in temperature or pressure from one cell to adjacent cells.
Special conditions 1 and 2 are intended to ensure that the non-
rechargeable lithium battery and its cells are designed to eliminate
the potential for uncontrollable failures. However, a certain number of
failures will occur due to various factors beyond the control of the
battery designer. Therefore, other special conditions are intended to
protect the airplane and its occupants if failure occurs.
Special conditions 3, 7, and 8 are self-explanatory.
Special condition 4 makes it clear that the flammable-fluid fire-
protection requirements of Sec. 25.863 apply to non-rechargeable
lithium battery and battery system installations. Section 25.863 is
applicable to areas of the airplane that could be exposed to flammable-
fluid leakage from airplane systems. Non-rechargeable lithium batteries
and battery systems contain an electrolyte that is a flammable fluid.
Special condition 5 requires that each non-rechargeable lithium
battery and battery system installation not damage surrounding
structure or adjacent systems, equipment, or electrical wiring from
corrosive fluids or gases that may escape in such a way as to cause a
major or more severe failure condition.
While special condition 5 addresses corrosive fluids and gases,
special condition 6 addresses heat. Special condition 6 requires that
each non-rechargeable lithium battery and battery system installation
have provisions to prevent any hazardous effect on airplane structure
or systems caused by the maximum amount of heat the battery
installation can generate due to any failure of it or its individual
cells. The means of meeting special conditions 5 and 6 may be the same,
but
[[Page 20321]]
the requirements are independent and address different hazards.
These special conditions apply to all non-rechargeable lithium
battery and battery system installations, in lieu of Sec.
25.1353(b)(1) through (4) at amendment 25-123. Sections 25.1353(b)(1)
through (4) at amendment 25-123 remain in effect for other battery
installations.
These special conditions contain the additional safety standards
that the Administrator considers necessary to establish a level of
safety equivalent to that established by the existing airworthiness
standards.
Applicability
As discussed above, these special conditions are applicable to the
Boeing Model 757-200, 757-200PF, 757-200CB, 757-300 series airplanes,
as modified by Honeywell. Should Honeywell apply at a later date for a
supplemental type certificate to modify any other model included on
Type Certificate No. A2NM to incorporate the same novel or unusual
design feature, these special conditions would apply to that model as
well.
Conclusion
This action affects only a certain novel or unusual design feature
on the Boeing Model 757-200, 757-200PF, 757-200CB, 757-300 series
airplanes. It is not a rule of general applicability and affects only
the applicant who applied to the FAA for approval of these features on
the airplane.
List of Subjects in 14 CFR Part 25
Aircraft, Aviation safety, Reporting and recordkeeping
requirements.
Authority Citation
The authority citation for these special conditions is as follows:
Authority: 49 U.S.C. 106(f), 40113, 44701, 44702, and 44704.
The Special Conditions
Accordingly, pursuant to the authority delegated to me by the
Administrator, the following special conditions are issued as part of
the type certification basis for the Boeing Model 757-200, 757-200PF,
757-200CB, 757-300 series airplanes, as modified by Honeywell.
In lieu of Sec. 25.1353(b)(1) through (4) at amendment 25-123, or
Sec. 25.1353(c)(1) through (4) at earlier amendments, each non-
rechargeable lithium battery and battery system installation must:
1. Be designed to maintain safe cell temperatures and pressures,
under all foreseeable operating conditions, to prevent fire and
explosion.
2. Be designed to prevent the occurrence of self-sustaining,
uncontrollable increases in temperature or pressure.
3. Not emit explosive or toxic gases, either in normal operation or
as a result of its failure, that may accumulate in hazardous quantities
within the airplane.
4. Meet the requirements of Sec. 25.863.
5. Not damage surrounding structure or adjacent systems, equipment,
or electrical wiring from corrosive fluids or gases that may escape in
such a way as to cause a major or more severe failure condition.
6. Have provisions to prevent any hazardous effect on airplane
structure or systems caused by the maximum amount of heat it can
generate due to any failure of it or its individual cells.
7. Have a failure-sensing and warning system to alert the flight
crew, in the event its failure affects safe operation of the airplane.
8. Have a means for the flight crew or maintenance personnel to
determine the battery charge state if the battery's function is
required for safe operation of the airplane.
Note: A battery system consists of the battery, battery charger,
and any protective monitoring and alerting circuitry or hardware
inside or outside of the battery. It also includes vents (where
necessary) and packaging. For the purpose of these special
conditions, a battery and the battery system is referred to as a
battery.
Issued in Fort Worth, Texas, on April 13, 2026.
Jorge R. Castillo,
Manager, Technical Policy Branch, Policy and Standards Division,
Aircraft Certification Service.
[FR Doc. 2026-07484 Filed 4-15-26; 8:45 am]
BILLING CODE 4910-13-P
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