[Federal Register Volume 83, Number 143 (Wednesday, July 25, 2018)]
[Rules and Regulations]
[Pages 35119-35122]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2018-15912]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 23

[Docket No. FAA-2018-0678; Special Conditions No. 23-290-SC]


Special Conditions: TCW Technologies, LLC; Piper Aircraft PA-32 
Series Airplanes; Installation of Rechargeable Lithium Batteries

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 Piper Aircraft 
Model PA-32-series airplanes. These airplanes, as modified by TCW 
Technologies, LLC, will have a novel or unusual design feature 
associated with the installation of a rechargeable lithium battery. The 
applicable airworthiness regulations do not contain adequate or 
appropriate safety standards for this design feature.

[[Page 35120]]

These special conditions contain the additional safety standards the 
Administrator considers necessary to establish a level of safety 
equivalent to that established by the existing airworthiness standards.

DATES: The effective date of these special conditions is July 25, 2018.
    We must receive your comments by September 10, 2018.

ADDRESSES: Send comments identified by docket number FAA-2018-0678 
using any of the following methods:
    <bullet> Federal eRegulations Portal: Go to http://www.regulations.gov 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 of 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.
    Privacy: The FAA will post all comments it receives, without 
change, to http://regulations.gov, including any personal information 
the commenter provides. Using the search function of the docket 
website, anyone can find and read the electronic form of all comments 
received into any FAA docket, including the name of the individual 
sending the comment (or signing the comment for an association, 
business, labor union, etc.). DOT's complete Privacy Act Statement can 
be found in the Federal Register published on April 11, 2000 (65 FR 
19477-19478), as well as at http://DocketsInfo.dot.gov.
    Docket: Background documents or comments received may be read at 
http://www.regulations.gov at any time. Follow the online instructions 
for accessing the docket or go to the 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: Ruth Hirt, Federal Aviation 
Administration, Aircraft Certification Service, Small Airplane 
Directorate, AIR-694, 901 Locust, Room 301, Kansas City, MO; telephone 
(816) 329-4108; facsimile (816)-329-4090.

SUPPLEMENTARY INFORMATION: 
    The FAA has determined that notice and opportunity for prior public 
comment are unnecessary because the substance of these special 
conditions has been subjected to the public comment process in several 
prior instances with no substantive comments received. It is unlikely 
that prior public comment would result in a significant change from the 
substance contained herein. The FAA therefore finds that good cause 
exists for making these special conditions effective upon issuance. The 
FAA is requesting comments to allow interested persons to submit views 
that may not have been submitted in response to the prior opportunities 
for comment.

------------------------------------------------------------------------
          Special conditions No.               Company/airplane model
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23-15-01-SC \1\...........................  Kestrel Aircraft Company/
                                             Model K-350.
23-09-02-SC \2\...........................  Cessna Aircraft Company/
                                             Model 525C (CJ4).
23-08-05-SC \3\...........................  Spectrum Aeronautical, LLC/
                                             Model 40.
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Comments Invited

    We invite 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. We ask 
that you send us two copies of written comments.
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    \1\ http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgSC.nsf/0/39B156C006EB842E86257EF3004BB13C?OpenDocument&Highlight=installation%20of%20rechargeable%20lithium%20battery.
    \2\ http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgSC.nsf/0/902232309C19F0D4862575CB0045AC0D?OpenDocument&Highlight=installation%20of%20rechargeable%20lithium%20battery.
    \3\ http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgSC.nsf/0/28E630294DCC27B986257513005968A3?OpenDocument&Highlight=installation%20of%20rechargeable%20lithium%20battery.
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    We will consider all comments we receive on or before the closing 
date for comments. We will consider comments filed late if it is 
possible to do so without incurring expense or delay. We may change 
these special conditions based on the comments we receive.

Background

    On May 5, 2017, TCW Technologies, LLC (TCW) applied for a 
supplemental type certificate (STC) to install a rechargeable lithium 
battery on Piper Aircraft Model PA-32-series airplanes. These airplanes 
are normal category airplanes with a maximum of 7 seats (including 
flightcrew), powered by a Lycoming O-540-series engine with 3,400 to 
3,600 pounds maximum takeoff weight, depending on the specific model.
    The current regulatory requirements for part 23 airplanes do not 
contain adequate requirements for use of rechargeable lithium batteries 
in airborne applications. This type of battery possesses certain 
failure and operational characteristics with maintenance requirements 
that differ significantly from that of the nickel-cadmium (Ni-Cd) and 
lead-acid rechargeable batteries currently approved in other normal, 
utility, acrobatic, and commuter category airplanes. Therefore, the FAA 
is issuing this special condition to address--
    <bullet> All characteristics of the rechargeable lithium batteries 
and their installation that could affect safe operation of the modified 
PA-32-series airplanes; and
    <bullet> Appropriate Instructions for Continued Airworthiness (ICA) 
that include maintenance requirements to ensure the availability of 
electrical power from the batteries when needed.

Type Certification Basis

    Under the provisions of Sec.  21.101, TCW must show that the PA-32 
series-airplanes, as changed, continue to meet the applicable 
provisions of the regulations incorporated by reference in Type 
Certificate Data Sheet (TCDS) No. A3SO \4\ or the applicable 
regulations in effect on the date of application for the change. The 
regulations incorporated by reference in the type certificate are 
commonly referred to as the ``original type certification basis.'' The 
regulations incorporated by reference are located in TCDS A3SO, pages 
24 through 28.
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    \4\ http://rgl.faa.gov/Regulatory_and_Guidance_Library/
rgMakeModel.nsf/0/44c795c1c122b21286257d74004d1952/$FILE/
A3SO_Rev_33.pdf.pdf
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    If the Administrator finds that the applicable airworthiness 
regulations (i.e., 14 CFR part 23) do not contain adequate or 
appropriate safety standards for the PA-32-series airplanes because of 
a novel or unusual design feature, special conditions are prescribed 
under the provisions of Sec.  21.16.
    The FAA issues special conditions, as defined in Sec.  11.19, under 
Sec.  11.38 and they become part of the type certification basis under 
Sec.  21.101.
    Special conditions are initially applicable to the models for which 
they are issued. Should the applicant apply for an STC to modify any 
other model(s) included on the same type certificate to incorporate the 
same novel or unusual design feature, the FAA would apply these special 
conditions to the other model(s) under Sec.  21.101.

[[Page 35121]]

Novel or Unusual Design Features

    The Piper PA-32-series airplanes will incorporate the following 
novel or unusual design features:
    The installation of a rechargeable lithium battery as backup power 
for avionics systems.

Discussion

    The applicable regulations governing the installation of batteries 
in general aviation airplanes were derived from Civil Air Regulations 
(CAR) 3 as part of the recodification that established 14 CFR part 23. 
The battery requirements identified in Sec.  23.1353 were a rewording 
of the CAR requirements. Additional rulemaking activities--resulting 
from increased incidents of Ni-Cd battery fire or failures--
incorporated Sec.  23.1353(f) and (g), amendments 23-20 and 23-21, 
respectively. The FAA did not envision the introduction of lithium 
battery installations at the time these regulations were published.
    The proposed use of rechargeable lithium batteries prompted the FAA 
to review the adequacy of these existing regulations. We determined the 
existing regulations do not adequately address the safety of lithium 
battery installations.
    Current experience with rechargeable lithium batteries in 
commercial or general aviation is limited. However, other users of this 
technology--ranging from personal computers, to wireless telephone 
manufacturers, to the electric vehicle industry--have noted safety 
problems with rechargeable lithium batteries. These problems, as 
described in the following paragraphs, include overcharging, over-
discharging, flammability of cell components, cell internal defects, 
and hazards resulting from exposure to extreme temperatures.
    1. Overcharging: In general, rechargeable lithium batteries are 
significantly more susceptible than their Ni-Cd or lead-acid 
counterparts to thermal runway, which is an internal failure that can 
result in self-sustaining increases in temperature and pressure. This 
is especially true for overcharging, which causes heating and 
destabilization of the components of the cell, leading to the formation 
(by plating) of highly unstable metallic lithium. The metallic lithium 
can ignite, resulting in a self-sustaining fire or explosion. Finally, 
the severity of thermal runaway due to overcharging increases with 
increasing battery capacity due to the higher amount of electrolyte in 
large batteries.
    2. Over-discharging: Discharge of some types of rechargeable 
lithium battery cells beyond the manufacturer's recommended 
specification can cause corrosion of the electrodes of the cell, 
resulting in loss of battery capacity that cannot be reversed by 
recharging. This loss of capacity may not be detected by the simple 
voltage measurements commonly available to flight crews as a means of 
checking battery status--a problem shared with Ni-Cd batteries. In 
addition, over-discharging has the potential to lead to an unsafe 
condition (creation of dendrites that could result in internal short 
circuit during the recharging cycle).
    3. Flammability of Cell Components: Unlike Ni-Cd and lead-acid 
batteries, some types of rechargeable lithium batteries use liquid 
electrolytes that are flammable. The electrolyte can serve as a source 
of fuel for an external fire, if there is a breach of the battery 
container.
    4. Cell Internal Defects: The rechargeable lithium batteries and 
rechargeable battery systems have a history of undetected cell internal 
defects. These defects may or may not be detected during normal 
operational evaluation, test, and validation. This may lead to an 
unsafe condition during in-service operation.
    5. Extreme Temperatures: Exposure to an extreme temperature 
environment has the potential to create major hazards. Care must be 
taken to ensure that the lithium battery remains within the 
manufacturer's recommended specification.

Applicability

    As discussed above, these special conditions are applicable to the 
PA-32-series airplanes. Should TCW apply at a later date for a 
supplemental type certificate to modify any other model added to Type 
Certificate No. A3SO with the same novel or unusual design feature, the 
FAA would apply these special conditions to that model as well.

Conclusion

    This action affects only certain novel or unusual design features 
on the PA-32-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.
    The substance of these special conditions has been subjected to the 
notice and comment period in several prior instances and has been 
derived without substantive change from those previously issued. It is 
unlikely that prior public comment would result in a significant change 
from the subject contained herein. Therefore, notice and opportunity 
for prior public comment hereon are unnecessary and the FAA finds good 
cause, in accordance with 5 U.S.C. 553(b)(3)(B) and 553(d)(3), for 
making these special conditions effective upon issuance. The FAA is 
requesting comments to allow interested persons to submit views that 
may not have been submitted in response to the prior opportunities for 
comment described above.

List of Subjects in 14 CFR Part 23

    Aircraft, Aviation safety, Signs and symbols.

Citation

    The authority citation for these special conditions is as follows:

    Authority: 49 U.S.C. 106(f), 106(g), 40113, 44701-44702, 44704; 
Pub. L. 113-53, 127 Stat 584 (49 U.S.C. 44704) note; 14 CFR 21.16 
and 21.101; and 14 CFR 11.38 and 11.19.

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 Piper Aircraft PA-32-series airplanes 
modified by TCW Technologies, LLC.

1. Installation of Lithium Battery

    The FAA adopts the following special conditions for lithium battery 
installations on Piper Aircraft PA-32-series airplanes in lieu of the 
requirements in Sec.  23.1353(a), (b), (c), (d), and (e), amendment 23-
62.
    Lithium battery installations on PA-32-series airplanes must be 
designed and installed as follows:
    (1) Safe cell temperatures and pressures must be maintained 
during--
    i. Normal operations;
    ii. Any probable failure conditions of charging or discharging or 
battery monitoring system; and
    iii. Any failure of the charging or battery monitoring system shown 
to not be extremely remote.
    (2) The rechargeable lithium battery installation must be designed 
to preclude explosion or fire in the event of a failure under 
(1)(1)(ii) and (1)(1)(iii) above.
    (3) Design of the rechargeable lithium batteries must preclude the 
occurrence of self-sustaining, uncontrolled increases in temperature or 
pressure.
    (4) No explosive or toxic gasses emitted by any rechargeable 
lithium battery in normal operation or as the result of any failure of 
the battery charging system, monitoring system, or battery 
installation, which is shown to not be extremely remote, may accumulate 
in hazardous quantities within the airplane.
    (5) Installations of rechargeable lithium batteries must meet the

[[Page 35122]]

requirements of Sec.  23.863(a) through (d), amendment 23-34.
    (6) No corrosive fluids or gases that may escape from any 
rechargeable lithium battery, may damage surrounding structure or any 
adjacent systems, equipment, electrical wiring, or the airplane in such 
a way as to cause a major or more severe failure condition, in 
accordance with Sec.  23.1309, amendment 23-62, and applicable 
regulatory guidance.
    (7) Each rechargeable lithium battery installation must have 
provisions to prevent any hazardous effect on structure or essential 
systems that may be caused by the maximum amount of heat the battery 
can generate during a short circuit of the battery or of its individual 
cells.
    (8) Rechargeable lithium battery installations must have a system 
to automatically control the charging rate of the battery to prevent 
battery overheating and overcharging, and either:
    i. A battery temperature sensing and over-temperature warning 
system with a means for automatically disconnecting the battery from 
its charging source in the event of an over-temperature condition; or
    ii. A battery failure sensing and warning system with a means for 
automatically disconnecting the battery from its charging source in the 
event of battery failure.
    (9) Any rechargeable lithium battery installation, the function of 
which is required for safe operation of the aircraft, must incorporate 
a monitoring and warning feature that will provide an indication to the 
appropriate flight crewmembers whenever the state of charge of the 
batteries has fallen below levels considered acceptable for dispatch of 
the aircraft.

    Note 1 to paragraph (9): Reference Sec.  23.1353(h) for dispatch 
consideration.

    (10) The Instructions for Continued Airworthiness (ICA) required by 
Sec.  23.1529 must contain maintenance requirements to assure that the 
battery has been sufficiently charged at appropriate intervals 
specified by the battery manufacturer and the equipment manufacturer 
that contain the rechargeable lithium battery or rechargeable lithium 
battery system. The lithium rechargeable batteries and lithium 
rechargeable battery systems must not degrade below specified ampere-
hour levels sufficient to power the aircraft system. The ICA must also 
contain procedures for the maintenance of replacement batteries to 
prevent the installation of batteries that have degraded charge 
retention ability or other damage due to prolonged storage at a low 
state of charge. Replacement batteries must be of the same manufacturer 
and part number as approved by the FAA.

    Note 2 to paragraph (10): Maintenance requirements include 
procedures that check battery capacity, charge degradation at 
manufacturers recommended inspection intervals, and replace 
batteries at manufacturer's recommended replacement schedule/time to 
prevent age-related degradation.


    Note 3 to paragraph (10): The term ``sufficiently charged'' 
means that the battery must retain enough charge, expressed in 
ampere-hours, to ensure that the battery cells will not be damaged. 
A battery cell may be damaged by low charge (i.e., below certain 
level), resulting in a reduction in the ability to charge and retain 
a full charge. This reduction would be greater than the reduction 
that may result from normal operational degradation.


    Note 4 to paragraph (10): Replacement battery in spares storage 
may be subject to prolonged storage at a low state of charge.


    Issued in Kansas City, Missouri on July 19, 2018.
Pat Mullen,
Manager, Small Airplane Standards Branch, Aircraft Certification 
Service.
[FR Doc. 2018-15912 Filed 7-24-18; 8:45 am]
BILLING CODE 4910-13-P