Document ID: FAA-2015-4279-0009
Agency: faa
Document Type: Rule
Title: Special Conditions: Gulfstream Aerospace Corp., Gulfstream GVI Airplane;  Non-Rechargeable Lithium Battery Installations
Posted Date: 2016-04-22T04:00Z

[Federal Register Volume 81, Number 78 (Friday, April 22, 2016)]
[Rules and Regulations]
[Pages 23573-23578]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2016-09311]

[[Page 23573]]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. FAA-2015-4279; Special Conditions No. 25-612-SC]

Special Conditions: Gulfstream Aerospace Corporation, Gulfstream 
GVI Airplane; Non-Rechargeable Lithium Battery Installations

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions.

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SUMMARY: These special conditions are issued for the Gulfstream 
Aerospace Corporation (Gulfstream) GVI airplane. This airplane 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 non-rechargeable lithium 
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: Effective April 22, 2017.

FOR FURTHER INFORMATION CONTACT: Nazih Khaouly, Airplane and Flight 
Crew Interface Branch, ANM-111, Transport Airplane Directorate, 
Aircraft Certification Service, 1601 Lind Avenue SW., Renton, 
Washington, 98057-3356; telephone 425-227-2432; facsimile 425-227-1149.

SUPPLEMENTARY INFORMATION

Future Requests for Installation of Non-Rechargeable Lithium Batteries

    The FAA anticipates that non-rechargeable lithium batteries will be 
installed in other makes and models of airplanes. We have determined to 
require special conditions for all applications requesting non-
rechargeable lithium battery installations, except the installations 
excluded in the Applicability section, until the airworthiness 
requirements can be revised to address this issue. Applying special 
conditions to these installations across the range of all transport-
airplane makes and models will ensure regulatory consistency among 
applicants.
    These are the first special conditions the FAA has issued for non-
rechargeable lithium battery installations on any airplane. The FAA has 
determined that these special conditions become effective 1 year after 
their publication in the Federal Register for reasons explained below 
in response to a public comment. The FAA intends for future special 
conditions for other makes and models to be effective on this same date 
or 30 days after their publication, whichever is later.

Background

    Gulfstream applied for several changes to type certificate no. 
T00015AT to install non-rechargeable lithium batteries in the Model GVI 
airplane. The Gulfstream Model GVI airplane is a twin-engine, 
transport-category airplane with a maximum passenger capacity of 19 and 
maximum takeoff weight of 99,600 pounds.

Type Certification Basis

    Under the provisions of Title 14, Code of Federal Regulations (14 
CFR) 21.101, Gulfstream must show that the design change and areas 
affected by the change continue to meet the applicable provisions of 
the regulations listed in type certificate no. T00015AT, or the 
applicable regulations in effect on the date of application for the 
change, except for earlier amendments as agreed upon by the FAA. The 
regulations listed in the type certificate are commonly referred to as 
the ``original type certification basis.'' The regulations listed in 
type certificate no. T00015AT are 14 CFR part 25 effective February 1, 
1965, including Amendments 25-1 through 25-120, 25-122, 25-124, and 25-
132. The certification basis also includes certain special conditions, 
exemptions, and equivalent-safety findings that are not relevant to 
these special conditions.
    In addition to the applicable airworthiness regulations and special 
conditions, the Gulfstream Model GVI airplane 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.
    If the Administrator finds that the applicable airworthiness 
regulations (i.e., 14 CFR part 25) do not contain adequate or 
appropriate safety standards for the Gulfstream Model GVI airplane 
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 Gulfstream Model 
GVI airplane model for which they are issued. Should the type 
certificate for that model be amended later to include any other model 
that incorporates the same novel or unusual design feature, or should 
any other model already included on the same type certificate be 
modified to incorporate the same novel or unusual design feature, these 
special conditions would also apply to the other model under Sec.  
21.101.
    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 GVI airplane will incorporate non-rechargeable 
lithium batteries.
    A battery system consists of the battery and any protective, 
monitoring, and alerting circuitry or hardware inside or outside of the 
battery, and venting capability where necessary. For the purpose of 
these special conditions, we refer to a battery and battery system as a 
battery.

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 re-codification of CAR 4b that 
established 14 CFR part 25 in February 1965. This re-codification 
basically reworded the CAR 4b battery requirements, which are currently 
in Sec.  25.1353(b)(1) through (b)(4). Non-rechargeable lithium 
batteries are novel and unusual with respect to the state of technology 
considered when these requirements were codified. These batteries 
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.
    Recent events involving rechargeable and non-rechargeable lithium 
batteries prompted the FAA to initiate a broad evaluation of these 
energy-storage technologies. In January 2013, two independent events 
involving rechargeable lithium-ion batteries revealed unanticipated 
failure modes. A National Transportation Safety Board (NTSB) letter to 
the FAA, dated May 22, 2014, which is available at http://www.ntsb.gov, 
filename A-14-032-036.pdf, describes these events.
    On July 12, 2013, an event involving a non-rechargeable lithium 
battery, in an emergency-locator-transmitter installation, demonstrated 
unanticipated failure modes. The United Kingdom's Air Accidents

[[Page 23574]]

Investigation Branch Bulletin S5/2013 describes this event.
    Some known uses of rechargeable and non-rechargeable lithium 
batteries on airplanes include:
     Flight deck and avionics systems such as displays, global-
positioning systems, cockpit voice recorders, flight-data recorders, 
underwater locator beacons, navigation computers, integrated avionics 
computers, satellite network and communication systems, communication-
management units, and remote-monitor electronic line-replaceable units;
     Cabin safety, entertainment, and communications equipment, 
including emergency-locator transmitters, life rafts, escape slides, 
seatbelt air bags, cabin-management systems, Ethernet switches, routers 
and media servers, wireless systems, internet and in-flight 
entertainment systems, satellite televisions, remotes, and handsets;
     Systems in cargo areas including door controls, sensors, 
video-surveillance equipment, and security systems.
    Some known potential hazards and failure modes associated with non-
rechargeable lithium batteries are:
     Internal failures: In general, these batteries are 
significantly more susceptible to internal failures that can result in 
self-sustaining increases in temperature and pressure (i.e., thermal 
runaway) than their nickel-cadmium or lead-acid counterparts. The 
metallic lithium can ignite, resulting in a self-sustaining fire or 
explosion.
     Fast or imbalanced discharging: Fast discharging or an 
imbalanced discharge of one cell of a multi-cell battery may create an 
overheating condition that results in an uncontrollable venting 
condition, which in turn leads to a thermal event or an explosion.
     Flammability: Unlike nickel-cadmium and lead-acid 
batteries, lithium batteries use higher energy and current in an 
electrochemical system that can be configured to maximize energy 
storage of lithium. They also use liquid electrolytes that can be 
extremely flammable. The electrolyte, as well as the electrodes, can 
serve as a source of fuel for an external fire if the battery casing is 
breached.
    Special condition no. 1 requires that each individual cell within a 
non-rechargeable lithium battery be designed to maintain safe 
temperatures and pressures. Special condition no. 2 addresses these 
same issues but for the entire battery. Special condition no. 2 
requires the battery 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 condition nos. 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 condition nos. 3, 7, and 8 are self-explanatory; the FAA 
does not provide further explanation for them at this time.
    The FAA requires special condition no. 4 to make it clear that the 
flammable-fluid fire-protection requirements of Sec.  25.863 apply to 
non-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. Non-rechargeable lithium batteries 
contain an electrolyte that is a flammable fluid.
    Special condition no. 5 requires each non-rechargeable lithium 
battery installation to not damage surrounding structure or adjacent 
systems, equipment, or electrical wiring from corrosive fluids or gases 
that may escape.
    Special condition no. 5 addresses corrosive fluids and gases, 
whereas special condition no. 6 addresses heat. Special condition no. 6 
requires each non-rechargeable lithium battery installation to 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 these special conditions may be the same, but they are 
independent requirements addressing different hazards.
    These special conditions apply to all non-rechargeable lithium 
battery installations in lieu of Sec.  25.1353(b)(1) through (b)(4) at 
Amendment 25-113. Sections 25.1353(b)(1) through (b)(4) at Amendment 
25-113 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.

Discussion of Comments

    Notice of proposed special conditions no. 25-15-09-SC, for the 
Gulfstream GVI airplane, was published in the Federal Register on 
November 20, 2015 (80 FR 72618). Five commenters provided comments.
    The Aerospace Industries Association (AIA) recommended revising 
proposed special condition no. 1 to read (see italics), ``. . . each 
non-rechargeable lithium battery installation must maintain safe cell 
temperatures and pressure under all foreseeable operating conditions to 
prevent fire and explosion by validating that the performance of non-
rechargeable lithium cells selected for use are acceptable with regards 
to the operating environment.'' AIA stated that this revision helps 
clarify the term ``foreseeable operating conditions'' as ``airplane 
operating and environmental conditions over which proper functioning of 
the equipment, systems, and installations is required to be considered 
includes the full normal operating envelope of the airplane as defined 
by the Airplane Flight Manual together with any modification to that 
envelope associated with abnormal or emergency procedures.'' AIA 
referenced FAA Advisory Circular (AC) 25.1309-1A and AC 25-11A to 
support this definition. The FAA does not agree with the proposal. The 
FAA intends for the term ``foreseeable operating conditions'' in these 
special conditions to not only apply at the airplane level but also at 
the battery-cell level. Therefore, we have not incorporated this 
proposed revision into the special condition.
    AIA recommended revising proposed special condition no. 2 to read, 
``. . . each non-rechargeable lithium battery installation must prevent 
the occurrence of self-sustaining, uncontrolled increases in 
temperature or pressure which would preclude continued safe flight and 
landing.'' AIA states that this change allows the use of airplane-level 
mitigation or design change to appropriately address the hazard. The 
FAA does not agree with the proposal. The FAA has determined that these 
special conditions are intended to require the battery, which includes 
its installation provisions, to be designed to prevent uncontrollable 
failure, and to not rely only on mitigation of a battery failure at the 
airplane level. Therefore, we have not revised proposed special 
condition no. 2.
    AIA recommended revising proposed special condition no. 3 to read, 
``. . . each non-rechargeable lithium battery installation must not 
emit explosive or toxic gases in normal operation, or as a result of 
any failure which is not shown to be extremely remote . . .'' The FAA 
does not agree with the proposal to exclude extremely remote failures. 
To ensure that all failures that are not extremely improbable are 
properly anticipated and accounted for, we have

[[Page 23575]]

not revised proposed special condition no. 3 to include the proposed 
words. Note that service history currently shows that battery failure 
is more frequent than extremely remote.
    AIA recommended deleting proposed special condition no. 4. AIA 
stated that it does not introduce a new airworthiness requirement and 
that it seems more appropriate to clarify applicability of an existing 
airworthiness requirement via policy. The FAA does not agree with the 
proposal. Section 25.863 historically has been applied to flammable 
fluids related to propulsion and hydraulic systems. The FAA has not 
issued guidance material at this time that would ensure a proper 
understanding that this section also applies to non-rechargeable 
lithium battery installations, which contain flammable fluid. We have 
determined to not delete proposed special condition no. 4.
    AIA recommended revising proposed special condition no. 5 to read, 
``. . . each non-rechargeable lithium battery installation must not 
allow escape of corrosive fluids or gases that may damage surrounding 
structure or any adjacent systems, equipment, or electrical wiring of 
the aircraft in such a way as to cause a hazardous or catastrophic 
failure condition.'' The FAA agrees with the comment in that the 
special condition requires clarification. The FAA intends for special 
condition no. 5 to be consistent with Sec.  25.1309. So, we added the 
words ``. . . in such a way as to cause a major or more-severe failure 
condition.'' The revised special condition now reads, ``. . . each non-
rechargeable lithium battery installation must 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.'' The FAA does not concur with 
excluding major failure conditions, nor limiting the types of failure 
conditions as proposed.
    AIA recommended revising proposed special condition no. 6 to read, 
``. . . each non-rechargeable lithium battery installation must 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 a single cell within a battery pack, which precludes 
continued safe flight and landing.'' AIA stated that they believe the 
intent of this special condition is to show that the battery design can 
tolerate a failure of a single cell. The FAA does not concur with AIA's 
recommendation. We intend for special condition no. 6 to require 
consideration of the maximum heat the battery can generate if it fails 
(that is, not just the heat from one cell for multi-cell batteries), 
including the heat generated from thermal runaway propagating from one 
cell to the other cells. AIA's proposed wording could be interpreted as 
only requiring consideration of the heat generated from a single cell. 
AIA also stated that design mitigation or analysis at the airplane 
level may be applied to show the design to be compliant. This comment 
addresses how to show compliance with the special condition and would 
not change the special condition. This comment can be addressed during 
the type certification projects.
    AIA recommended deleting proposed special condition no. 7, which 
reads, ``. . . each non-rechargeable lithium battery installation must 
be capable of automatically controlling the discharge rate of each cell 
to prevent cell imbalance, back-charging, overheating, and 
uncontrollable temperature and pressure.'' AIA stated that the hazard 
intended to be addressed by this special condition would be prevented 
by meeting special condition nos. 1, 2, 4 and 5. The intent of proposed 
special condition no. 7 was to also address charge imbalance because an 
in-service event demonstrated that a charge imbalance is one of many 
failure modes that can lead to a thermal runaway condition. However, 
the FAA agrees with deleting proposed special condition no. 7 because 
compliance with special condition nos. 1 and 2 accomplish the safety 
objectives of proposed special condition no. 7.
    AIA recommended deleting proposed special condition no. 8, which 
reads, ``. . . each non-rechargeable lithium battery installation must 
have a means to automatically disconnect from its discharging circuit 
in the event of an over-temperature condition, cell failure, or battery 
failure.'' The FAA agrees with deleting this proposed special condition 
because doing so does not relieve applicants from the need to comply 
with Sec.  25.1309. In addition to Sec.  25.1309, all applicable 
system-level requirements may require the connected system to 
automatically disconnect from the battery discharging circuit in the 
event of an over-temperature condition, cell failure, or battery 
failure.
    AIA recommended revising proposed special condition no. 9 (which is 
now special condition no. 7 in these special conditions) to read, ``. . 
. each non-rechargeable lithium battery installation must have a 
failure sensing and warning system to alert the flightcrew if its 
failure affects precludes continued safe flight and landing of the 
airplane.'' AIA stated that this proposed special condition repeats the 
criteria defined in Sec.  25.1309, and therefore is a duplication of 
current Federal aviation requirements. Proposed special condition no. 9 
has the same purpose as that of Sec.  25.1309(c), which is to require 
flightcrew alerting if failure of a battery installation, in itself or 
in relation to a system that performs an airplane-level function, could 
result in ``unsafe system operating conditions'' as stated in Sec.  
25.1309(c). The FAA's intent for this special condition is to emphasize 
this requirement specifically for non-rechargeable lithium battery 
installations. We do not concur with AIA's recommendation because the 
revised wording does not fully address the ``unsafe system operating 
conditions'' as required in Sec.  25.1309(c).
    AIA recommended revising proposed special condition no. 10 (which 
is now special condition no. 8 in these special conditions) to read, 
``. . . each non-rechargeable lithium battery installation must have a 
means for the flightcrew or maintenance personnel to determine the 
battery charge state if the battery's function is required for 
continued safe flight and landing of the airplane.'' AIA stated that 
this proposed special condition repeats the criteria defined in Sec.  
25.1309, and therefore is a duplication of current Federal aviation 
requirements. For similar reasons given in our response to the AIA 
comment on proposed special condition no. 9, we do not concur with 
AIA's recommendation. The FAA's intent for this special condition is to 
emphasize this requirement specifically for non-rechargeable lithium 
battery installations. We do not concur with AIA's recommendation 
because the revised wording does not fully address the ``unsafe system 
operating conditions'' as required in Sec.  25.1309(c).
    The Boeing Company commented that they concur with AIA's comments.
    The Boeing Company also requested that the FAA provide adequate 
time before non-rechargeable lithium battery special conditions become 
effective, to support validation activities by foreign civil 
airworthiness authorities (FCAA) and to not adversely impact future 
airplane deliveries by all applicants. The Boeing Company stated that 
they have been ``informed by FCAAs that validation activities for FAA 
type certificate data sheet certification basis changes can take up to 
12 months after receipt of application.'' The FAA agrees that adequate 
time is necessary to allow Gulfstream, and other applicants for which 
similar special conditions will be issued, to coordinate with FCAAs, 
and to conduct other activities associated

[[Page 23576]]

with implementing these special conditions, which have not been 
required for previous approvals. These are the first special conditions 
the FAA has issued for a non-rechargeable lithium battery installation 
on any airplane. Likewise, we have determined that an effective date of 
one year after special conditions publication is appropriate. The FAA 
also has been coordinating with other applicants to develop proposed 
special conditions for their projects involving non-rechargeable 
lithium batteries. The FAA intends for future special conditions, for 
other airplane makes and models, to be effective on this same date or 
30 days after their publication, whichever is later.
    The Boeing Company commented that ``. . . these special conditions 
should clearly indicate the scope of changes for which the 
certification basis is deemed inadequate and requires application of 
the special conditions.'' The Boeing Company made this comment in 
regards to the applicability of these special conditions to batteries 
that have less than 2 watt-hours of energy and meet Underwriters 
Laboratories (UL) 1642 or UL 2054. The FAA has determined that the use 
of UL 1642 and UL 2054 should be addressed as a method-of-compliance 
issue rather than exclusion criteria for certain battery sizes. These 
special conditions are to apply to all non-rechargeable lithium 
batteries regardless of their size. These special conditions require 
this where it states ``. . . each non-rechargeable lithium battery 
installation must . . .''
    Airbus commented that they assume that the FAA considers the 
standards in Radio Technical Commission for Aeronautics (RTCA) DO-227, 
Minimum Operational Performance Standard for Lithium Batteries, to be 
an acceptable means of compliance with the special conditions that 
address battery-qualification aspects. Airbus also commented that they 
assume that compliance with the other special conditions is 
demonstrated through analysis of battery integration in the airplane 
physical and functional environment. These comments address how to show 
compliance with the special conditions and would not change the special 
conditions. These comments can be addressed during the type 
certification projects.
    Airbus commented that batteries that are Category I, as defined in 
RTCA DO-227, should be excluded from proposed special condition nos. 1 
through 8 (which are special condition nos. 1 through 6 in these 
special conditions). RTCA DO-227 defines these batteries as ``solid-
cathode cells that contain less than 0.15 grams of lithium or lithium 
alloy, and batteries that use not more than four such cells.'' The FAA 
does not concur. These special conditions are intended to provide an 
appropriate level of safety for all non-rechargeable lithium battery 
installations.
    Bombardier provided the following comment on proposed special 
condition no. 3: ``The quantity of [lithium battery] gas that will 
constitute a hazard is difficult to define and test. An outgassing 
limit in corresponding to cell size/number would be easier to comply 
with and test. This should only apply in the failure case, as in normal 
cell operation non-rechargeable [lithium batteries] are expected to 
remain sealed. We recommend wording that would instead limit cell size/
number and require cell isolation to minimize hazard to airplane and 
occupant in case of failure and be sealed in normal operation. Exposure 
to occupants may be achieved by locating battery installations away 
from occupant areas on the airplane.'' The FAA does not agree with the 
proposal. The FAA considers that a special condition that limits the 
number of cells and their size would be unnecessarily restrictive. Note 
that this special condition does not require applicants to determine 
the quantity of gas that would constitute a hazard. For example, an 
acceptable means of complying with this special condition is to 
demonstrate, through tests, that all emitted gasses are contained or 
vented overboard through designed ports. However, this special 
condition does allow explosive and toxic gases to be uncontained and 
not vented overboard if they do not accumulate in hazardous quantities 
within the airplane.
    Bombardier commented that a design that prevents fluids and gases 
from escaping the installation should be an acceptable means of 
complying with proposed special condition no. 5. Bombardier recommended 
addressing the need for fluid containment. These comments address how 
to show compliance with the special conditions and would not change the 
special conditions. These comments can be addressed during the type 
certification projects.
    Transport Canada recommended revising proposed special condition 
no. 1 to address ``all hazards.'' We have not revised this special 
condition because it is intended to address only the cell-level 
hazards, which are fire and explosion. All hazards are addressed 
through compliance with the complete set of applicable special 
conditions.
    Transport Canada recommended adding a sentence to proposed special 
condition no. 2 that reads, ``Batteries that are capable of venting 
toxic gases shall not be installed or used in the aircraft cockpit.'' 
Transport Canada stated that adding this sentence would harmonize the 
special condition with Technical Standard Order (TSO) TSO-C142a, Non-
Rechargeable Lithium Cells and Batteries, and RTCA DO-227, Minimum 
Operational Performance Standard for Lithium Batteries. The FAA does 
not agree with the proposal and did not add this sentence to special 
condition no. 2. We consider the special condition without this 
sentence more appropriate because it allows an applicant to demonstrate 
that the amount of gases a battery vents is not a hazard to the flight 
deck, and allows installation of those batteries.
    Transport Canada recommended revising proposed special condition 
no. 5 to read, ``. . . each non-rechargeable lithium battery 
installation must 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.'' The FAA concurs, and has incorporated the recommended 
wording into special condition no. 5. We explain our agreement with 
adding these words in our above response to AIA's comment on this 
special condition.
    Transport Canada recommended revising proposed special condition 
no. 6 to refer to ``essential systems'' instead of ``systems,'' because 
the FAA previously found that wording acceptable for rechargeable 
lithium battery special conditions. Alternatively, Transport Canada 
recommended that the FAA be consistent and use ``systems'' for both 
rechargeable and non-rechargeable lithium battery special conditions in 
the future. The intent of this special condition is to address the 
hazards to the airplane regardless of the system critically. The FAA 
agrees with using ``systems'' in this special condition and in the next 
special conditions we propose for a rechargeable lithium battery 
installation.
    Transport Canada recommended revising proposed special condition 
no. 6 to read, ``. . .each non-rechargeable lithium battery 
installation must 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 discharge condition and/or failure of it or its 
individual cells.'' The FAA does not agree with the proposal. The 
maximum heat generated due to any battery or cell failure (for example, 
the heat generated during thermal runaway) represents the

[[Page 23577]]

worst-case condition. The maximum heat generated during ``any discharge 
condition'' will not exceed this worst-case condition. Therefore, the 
FAA did not revise this special condition.
    Transport Canada recommended including ``unbalanced discharge'' in 
the list of conditions intended to be prevented in proposed special 
condition no. 7. As a result of a comment from AIA addressed above, the 
FAA deleted proposed special condition no. 7 because compliance with 
special condition nos. 1 and 2 accomplish its safety objectives. 
Special conditions 1 and 2 also address unbalanced discharge.
    Transport Canada recommended revising proposed special condition 
no. 8 to read, ``. . . each non-rechargeable lithium battery 
installation must have a means to automatically and permanently 
disconnect from its discharging circuit in the event of an over-
temperature condition, over-current condition, cell failure, or battery 
failure.'' Transport Canada recommended this change to raise awareness 
of issues associated with positive temperature coefficient protective 
devices in lithium battery design. As discussed above in response to an 
AIA comment, the FAA deleted proposed special condition no. 8, and 
therefore, has not incorporated the recommended revision.
    Transport Canada recommended adding a special condition to require 
instructions for continued airworthiness (ICAs) to address handling and 
storage of non-rechargeable lithium batteries at a minimum. The FAA has 
not added the recommended special condition because Sec.  25.1529 
requires ICAs for non-rechargeable lithium battery installations. To 
ensure compliance with Sec.  25.1529, the FAA is documenting acceptable 
methods of compliance with Sec.  25.1529 for non-rechargeable lithium 
battery installations as part of the certification process. These 
methods of compliance address the issues Transport Canada raised. The 
FAA previously included a special condition that requires compliance 
with Sec.  25.1529 in rechargeable lithium battery special conditions. 
For consistency and the above-stated reasons, the FAA plans to no 
longer include that special condition in special conditions applicable 
to rechargeable lithium batteries.
    Transport Canada recommended ``the special condition be written in 
such a way as to drive the requirement for original equipment 
manufacturers to complete an adequate failure modes and effects 
analysis (FMEA) in order to discover and mitigate for all failure 
modes, including those that are less well known.'' The FAA does not 
agree with the proposal. The current FAA AC 25.1309-1A and Aviation 
Rulemaking Advisory Committee (ARAC) recommended AC 25.1309-Arsenal 
contain guidance to utilize FMEA in the safety-assessment process. The 
FAA believes that these special conditions, and the hazards identified, 
drive the FMEA or any other system-safety assessment tool to 
comprehensively assess the risk of battery failures. We believe that we 
have accomplished Transport Canada's recommendation.
    Transport Canada recommended changes to FAA TSO-142a, Non-
Rechargeable Lithium Cells and Batteries. Their comment did not 
recommend changes to these special conditions; as such, this comment 
does not affect these special conditions.
    Transport Canada recommended adding a special condition that reads, 
``Equipment manufacturers intending to use lithium-metal batteries in 
aircraft equipment must demonstrate that the battery design 
incorporates an acceptable level of circuit protection to mitigate 
against known failure modes including, but not limited to, external 
short-circuits and unbalanced discharge.'' Transport Canada referenced 
Air Accidents Investigation Branch (AAIB) Safety Recommendation 2015-
016 to support this recommendation, which states, ``It is recommended 
that the Federal Aviation Administration, in conjunction with the 
European Aviation Safety Agency and Transport Canada, require equipment 
manufacturers intending to use lithium-metal batteries in aircraft 
equipment to demonstrate that the battery design incorporates an 
acceptable level of circuit protection to mitigate against known 
failure modes including, but not limited to, external short-circuits 
and unbalanced discharge.'' The FAA does not concur with adding this 
special condition. The AAIB wrote their recommendation based on a non-
rechargeable lithium battery installation that was approved before the 
FAA determined the need to apply special conditions. Their 
recommendation is specific to incorporating circuit protection, which 
is a means to achieve the safety level defined in these special 
conditions. The FAA intends for these special conditions to be 
performance-based. Additionally, type certificate and supplemental type 
certificate applicants, and not the equipment manufacturers who have 
not applied for the installation approval, are required to demonstrate 
compliance to applicable special conditions.
    The FAA has determined that ``uncontrolled'' in special condition 
no. 2 should be ``uncontrollable'' to more accurately describe the 
concern. This revision does not change the intended meaning of this 
special condition.
    Except as discussed above, the special conditions are adopted as 
proposed.

Applicability

    As discussed above, these special conditions are applicable to the 
Gulfstream Model GVI airplane. Should Gulfstream apply at a later date 
for a change to the type certificate to include another model 
incorporating the same novel or unusual design feature, these special 
conditions would apply to that model as well.
    These special conditions are only applicable to design changes 
applied for after its effective date. The existing airplane fleet and 
follow-on deliveries of airplanes with previously certified non-
rechargeable lithium battery installations are not affected.
    These special conditions are not applicable to changes to 
previously certified non-rechargeable lithium battery installations 
where the only change is either cosmetic or relocating the installation 
to improve the safety of the airplane and occupants. The FAA determined 
that this exclusion is in the public interest because the need to meet 
all of the special conditions might otherwise deter design changes that 
solely involve relocating batteries to improve safety. A cosmetic 
change is a change in appearance only, and does not change any function 
or safety characteristic of the battery installation.

Conclusion

    This action affects only certain novel or unusual design features 
on one model of airplane. It is not a rule of general applicability.

List of Subjects in 14 CFR Part 25

    Aircraft, Aviation safety, Reporting and record keeping 
requirements.

    The authority citation for these special conditions is as follows:

    Authority:  49 U.S.C. 106(g), 40113, 44701, 44702, 44704.

The Special Conditions

    Accordingly, the following special conditions are part of the type 
certification basis for Gulfstream Model GVI airplanes.

Non-Rechargeable Lithium Battery Installations

    In lieu of Sec.  25.1353(b)(1) through (b)(4) at Amendment 25-113, 
each non-rechargeable lithium battery installation must:
    1. Maintain safe cell temperatures and pressures under all 
foreseeable operating conditions to prevent fire and explosion.

[[Page 23578]]

    2. 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 
flightcrew if its failure affects safe operation of the airplane.
    8. Have a means for the flightcrew or maintenance personnel to 
determine the battery charge state if the battery's function is 
required for safe operation of the airplane.

    Note 1: A battery system consists of the battery 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 Renton, Washington, on April 14, 2016.
Victor Wicklund,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2016-09311 Filed 4-21-16; 8:45 am]
 BILLING CODE 4910-13-P