[Federal Register Volume 88, Number 63 (Monday, April 3, 2023)]
[Rules and Regulations]
[Pages 19547-19549]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-06729]



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 Rules and Regulations
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 This section of the FEDERAL REGISTER contains regulatory documents 
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  Federal Register / Vol. 88, No. 63 / Monday, April 3, 2023 / Rules 
and Regulations  

[[Page 19547]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. FAA-2022-1441; Special Conditions No. 25-817-SC]


Special Conditions: Blackhawk Aerospace Technologies, Textron 
Model 500 Series 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 Textron Model 500/
550/S550/560/560XL/560XLS airplanes. These airplanes, as modified by 
Blackhawk Aerospace Technologies (Blackhawk), 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 electronic GI 275 Standby Instruments 
containing rechargeable lithium-ion batteries. 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 Blackhawk on April 3, 2023. Send 
comments on or before May 18, 2023.

ADDRESSES: Send comments identified by Docket No. FAA-2022-1441 using 
any of the following methods:
     Federal eRegulations Portal: Go to https://www.regulations.gov/ and follow the online instructions for sending 
your comments electronically.
     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.
     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.
     Fax: Fax comments to Docket Operations at 202-493-2251.
    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 https://www.regulations.gov/, 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 
below. Comments the FAA receives, which are not specifically designated 
as CBI, will be placed in the public docket for these special 
conditions.
    Docket: Background documents or comments received may be read at 
https://www.regulations.gov/ 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 
Section, AIR-623, 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 [email protected].

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 Sec.  11.38(b), that new comments 
are unlikely, and notice and comment prior to this publication are 
unnecessary.

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, and will consider comments filed late if it is possible to do 
so without incurring delay. The FAA may change these special conditions 
based on the comments received.

Background

    On February 24, 2020, Blackhawk applied for a supplemental type 
certificate to install rechargeable lithium batteries and battery 
systems, in the Textron Model 500 series airplanes, for electronic GI 
275 Standby Instruments. The Textron Model 500 series airplane, 
approved under Type Certificate No. A22CE, is a twin-engine, transport-
category airplane with maximum seating capacity for 7 to 12 passengers 
and a maximum takeoff weight of between 10,850 to 20,330 pounds, 
depending upon model.

Type Certification Basis

    Under the provisions of title 14, Code of Federal Regulations (14 
CFR) 21.101, Blackhawk must show that the Textron

[[Page 19548]]

Model 500 series airplanes, as changed, continue to meet the applicable 
provisions of the regulations listed in Type Certificate No. A22CE 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 Textron Model 500 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 Textron Model 500 series airplanes must comply with the 
fuel-vent and 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 Sec.  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 Textron Model 500 series airplanes will incorporate the 
following novel or unusual design feature:
    Electronic GI 275 Standby Instruments containing rechargeable 
lithium-ion batteries.

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 
Textron Model 500 series airplanes. Should Blackhawk apply at a later 
date for a supplemental type certificate to modify any other model 
included on Type Certificate No. A22CE 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 one model series of 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), 106(g), 40113, 44701, 44702, 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 Textron Model 500 series airplanes, as 
modified by Blackhawk.

Rechargeable Lithium Battery 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, each 
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, and automatically 
control the charge rate of each cell to protect

[[Page 19549]]

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 flight 
crew if its failure affects safe operation of the airplane.
    (8) If its function is required for safe operation of the airplane, 
have a monitoring and warning feature that alerts the flight crew when 
its charge state falls below acceptable levels.
    (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: The battery system consists of the batteries, 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 battery system are referred to as a 
battery.


    Issued in Kansas City, Missouri, on March 28, 2023.
Patrick R. Mullen,
Manager, Technical Innovation Policy Branch, Policy and Innovation 
Division, Aircraft Certification Service.
[FR Doc. 2023-06729 Filed 3-31-23; 8:45 am]
BILLING CODE 4910-13-P