Rule2026-07483
Special Conditions: ALOFT AeroArchitects, Gulfstream Aerospace Corporation Model G-IV, GIV-X, GV, and GV-SP Airplanes; Rechargeable Lithium Batteries and Battery System Installations
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 Gulfstream Aerospace Corporation (Gulfstream) Model G-IV, GIV-X, GV, and GV-SP series airplanes, as modified by ALOFT AeroArchitects (ALOFT). These airplanes 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 a main ship rechargeable lithium battery. 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 20317-20319]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2026-07483]
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Rules and Regulations
Federal Register
________________________________________________________________________
This section of the FEDERAL REGISTER contains regulatory documents
having general applicability and legal effect, most of which are keyed
to and codified in the Code of Federal Regulations, which is published
under 50 titles pursuant to 44 U.S.C. 1510.
The Code of Federal Regulations is sold by the Superintendent of Documents.
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Federal Register / Vol. 91, No. 73 / Thursday, April 16, 2026 / Rules
and Regulations
[[Page 20317]]
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. FAA-2026-3490; Special Conditions No. 25-888-SC]
Special Conditions: ALOFT AeroArchitects, Gulfstream Aerospace
Corporation Model G-IV, GIV-X, GV, and GV-SP Airplanes; Rechargeable
Lithium Batteries and Battery System Installations
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 Gulfstream
Aerospace Corporation (Gulfstream) Model G-IV, GIV-X, GV, and GV-SP
series airplanes, as modified by ALOFT AeroArchitects (ALOFT). These
airplanes 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 a main ship
rechargeable lithium battery. 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 ALOFT on April 16, 2026. Send
comments on or before June 1, 2026.
ADDRESSES: Send comments identified by Docket No. FAA-2026-3490 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#caa4abb0a3a2e4a1a2aba5bfa6b38aacababe4ada5bc"><span class="__cf_email__" data-cfemail="08666972616026636069677d6471486e6969266f677e">[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.
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 23, 2026, ALOFT applied for a supplemental type
certificate for the installation of rechargeable lithium batteries and
battery systems in the Gulfstream Model G-IV, GIV-X, GV, and GV-SP
series airplanes. These airplanes, approved under Type Certificate No.
A12EA, are twin-engine transport category airplanes with a maximum
seating capacity of 19 passengers. These airplanes have a maximum
takeoff weight between 46,500 and 91,400 pounds, depending on the
model.
Type Certification Basis
Under the provisions of title 14, Code of Federal Regulations (14
CFR) 21.101, ALOFT must show that the Gulfstream Model G-IV, GIV-X, GV,
and GV-SP
[[Page 20318]]
series airplanes, as changed, continue to meet the applicable
provisions of the regulations listed in Type Certificate No. A12EA 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 Gulfstream Model G-IV, GIV-X, GV,
and GV-SP series 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 applicant 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 Gulfstream Model G-IV, GIV-X, GV, and GV-SP series
airplanes must comply with 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 Gulfstream Model G-IV, GIV-X, GV, and GV-SP series airplanes,
as modified by ALOFT, will incorporate the following novel or unusual
design features:
Installation of a main ship rechargeable lithium battery.
Discussion
Rechargeable lithium batteries and battery systems are considered
to be a novel or unusual design feature in transport category
airplanes, with respect to the requirements in Sec. 25.1353. This type
of battery has certain failure, operational, and maintenance
characteristics that differ significantly from those of the nickel-
cadmium and lead-acid rechargeable batteries currently approved for
installation on transport category airplanes. These 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
introduces failure modes that require unique design considerations,
such as provisions for thermal management.
Special Condition 1 requires that each individual cell within a
battery and battery system be designed to maintain safe temperatures
and pressures. Special Condition 2 addresses these same issues but for
the entire battery system.
Special Condition 2 requires that the batteries and battery system
be designed to prevent propagation of a thermal event, such as self-
sustained, uncontrolled increases in temperature or pressure from one
cell to adjacent cells.
Special Conditions 1 and 2 are intended to ensure that the cells
and battery system 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 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 clarifies that the flammable-fluid fire-
protection requirements of Sec. 25.863 apply to rechargeable lithium
battery installations. Section 25.863 is applicable to areas of the
airplane that could be exposed to flammable fluid leakage from airplane
systems. Rechargeable lithium batteries contain electrolyte that is a
flammable fluid.
Special Condition 5 requires each rechargeable lithium battery and
battery system installation to 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.
Special Condition 6 requires each rechargeable lithium battery and
battery system installation to 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.
The means of meeting special conditions 5 and 6 may be the same, but
they are independent requirements addressing different hazards. Special
Condition 5 addresses corrosive fluids and gases, whereas special
condition 6 addresses heat.
Special Condition 9 requires rechargeable lithium batteries and
battery systems to have ``automatic'' means, for charge rate and
disconnect, due to the fast acting nature of lithium battery chemical
reactions. Manual intervention would not be timely or effective in
mitigating the hazards associated with these batteries.
These special conditions apply to all rechargeable lithium
batteries and battery system installations 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. Those regulations will remain in
effect for other battery installations on these airplanes.
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
Gulfstream Model G-IV, GIV-X, GV, and GV-SP series airplanes, as
modified by ALOFT. Should ALOFT apply at a later date for a
supplemental type certificate to modify any other model included on
Type Certificate No. A12EA to incorporate the same novel or unusual
design feature, these special conditions would apply to that model as
well.
Conclusion
This action affects only certain novel or unusual design features
on the Gulfstream Model G-IV, GIV-X, GV, and GV-SP 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 Gulfstream Model G-IV, GIV-X, GV, and
GV-SP series airplanes, as modified by ALOFT.
In lieu of Title 14, Code of Federal Regulations (14 CFR)
25.1353(b)(1) through (4) at amendment 25-123 or Sec. 25.1353(c)(1)
through (4) at earlier amendments, each rechargeable lithium battery
installation must:
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, and automatically
control
[[Page 20319]]
the charge rate of each cell to protect against adverse operating
conditions, such as cell imbalance, back charging, overcharging, and
overheating.
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
flightcrew if its failure affects safe operation of the airplane.
8. Have a monitoring and warning feature that alerts the flightcrew
when its charge state falls below acceptable levels if its function is
required for safe operation of the airplane.
9. Have a means to automatically disconnect from its charging
source in the event of an over-temperature condition, cell failure or
battery failure.
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 this special condition,
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. 2026-07483 Filed 4-15-26; 8:45 am]
BILLING CODE 4910-13-P
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</html>Indexed from Federal Register on April 16, 2026.
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