[Federal Register Volume 82, Number 77 (Monday, April 24, 2017)]
[Rules and Regulations]
[Pages 18841-18843]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2017-08234]

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. 


Federal Register / Vol. 82, No. 77 / Monday, April 24, 2017 / Rules 
and Regulations

[[Page 18841]]


Federal Aviation Administration

14 CFR Part 23

[Docket No. FAA-2017-0381; Special Conditions No. 23-280-SC]

Special Conditions: Viking Air, Ltd., Models DHC-6-100/-200/-300; 
Avmax Aviation Services, Inc., Installation of Rechargeable Lithium 

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions; request for comments.


SUMMARY: These special conditions are issued for the Viking Air, Ltd., 
models DHC-6-100/-200/-300, Twin Otter, Turbopropeller airplanes. This 
airplane, as modified by Avmax Aviation Services, Inc., will have a 
novel or unusual design feature associated with the use of a 
replacement option of a lithium battery instead of nickel-cadmium and 
lead-acid rechargeable 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: The effective date of these special conditions is April 24, 
    We must receive your comments by June 8, 2017.

ADDRESSES: Send comments identified by docket number FAA-2017-0381 
using any of the following methods:
    [square] Federal eRegulations Portal: Go to http://www.regulations.gov and follow the online instructions for sending your 
comments electronically.
    [square] 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.
    [square] 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.
    [square] 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 Web 
site, 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.

Administration, Aircraft Certification Service, Small Airplane 
Directorate, ACE-114, 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 hereon are impracticable because 
these procedures would significantly delay issuance of the approval 
design and thus delivery of the affected aircraft. In addition, the FAA 
has determined, in accordance with 5 U.S.C. 553(b)(3)(B) and 553(d)(3), 
that notice and opportunity for prior public comment hereon are 
unnecessary because the substance of these special conditions has been 
subject to the public comment process in several prior instances with 
no substantive comments received. The FAA therefore finds that good 
cause exists for making these special conditions effective upon 

    \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.

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

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.
    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.


    On January 18, 2016, Avmax Aviation Services, Inc., (Avmax) applied 
for a supplemental type certificate (STC) to install a rechargeable 
lithium battery on the Viking Air, Ltd. (Viking Air), models DHC-6-100/
-200/-300, Twin Otter, Turbopropeller airplanes. These are normal 
category airplanes, powered by two Pratt & Whitney Canada PT6A-20 
engines (-100 and -200) or two PT6A-27 engines (-300). The maximum 
takeoff weight is 12,500 pounds (5,670 kg) for the -300, but lesser for 
the -100 and -200.
    The current regulatory requirements for part 23 airplanes do not 
contain adequate requirements for use of

[[Page 18842]]

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 proposing this special condition to 
address (1) all characteristics of the rechargeable lithium batteries 
and their installation that could affect safe operation of the modified 
models DHC-6-100/-200/-300 Turbopropeller airplanes, and (2) 
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, Avmax must show that the 
models DHC-6-100/-200/-300 Turbopropeller airplanes, as changed, 
continue to meet the applicable provisions of the regulations 
incorporated by reference in Type Certificate Data Sheet No. A9EA \4\ 
or the applicable regulations in effect on the date of application for 
the change.

    \4\ http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/AB4F5DD989BB1B4E86257FF100542804?OpenDocument.

    If the Administrator finds that the applicable airworthiness 
regulations (i.e., Civil Air Regulations [CAR] 3) do not contain 
adequate or appropriate safety standards for the models DHC-6-100/-200/
-300 Turbopropeller 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 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.

Novel or Unusual Design Features

    The Viking Air models DHC-6-100/ -200/-300 Turbopropeller airplanes 
will incorporate the following novel or unusual design features:
    The installation of a rechargeable lithium battery as a main or 
engine start aircraft battery.


    The applicable regulations governing the installation of batteries 
in general aviation airplanes were derived from 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, as a result of 
increased incidents of Ni-Cd battery fire or failures, incorporated 
Sec.  23.1353(f) and (g) at amendments 23-20 and 23-21 respectively. 
However, the regulation prescribed was not for lithium battery 
    The proposed use of rechargeable lithium batteries prompted the FAA 
to review the adequacy of these existing regulations. We found that 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 include 
overcharging, over-discharging, flammability of cell components, cell 
internal defects, and those resulting from exposure to extreme 
temperatures that are described in the following paragraphs.
    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 
    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.


    The special conditions are applicable to the models DHC-6-100/-200/
-300 Turbopropeller airplanes. Should Avmax apply at a later date for 
an STC to modify any other model included on the same type certificate 
to incorporate the same novel or unusual design feature, the special 
conditions would apply to that model as well.


    This action affects only certain novel or unusual design features 
on the models DHC-6-100/-200/-300 Turbopropeller 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), 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

[[Page 18843]]

prior opportunities for comment described above.

List of Subjects in 14 CFR Part 23

    Aircraft, Aviation safety, Signs and symbols.


The authority citation for these special conditions is as follows:

    Authority:  49 U.S.C. 106(g), 40113 and 44701; 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 Viking Air, Ltd., models DHC-6-100/-
200/-300 Turbopropeller airplanes modified by Avmax Aviation Services, 

1. Installation of Lithium Battery

    The FAA adopts that the following special conditions be applied to 
lithium battery installations on the models DHC-6-100/-200/-300 
Turbopropeller airplanes in lieu of the requirements Sec.  
23.1353(a)(b)(c)(d)(e), amendment 49.
    Lithium battery installations on the models DHC-6-100/-200/-300 
Turbopropeller airplanes must be designed and installed as follows:
    (1) Safe cell temperatures and pressures must be maintained 
    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 not 
shown to be extremely remote.
    (2) The rechargeable lithium battery installation must be designed 
to preclude explosion or fire in the event of 1(1)(ii) and 1(1)(iii) 
    (3) Design of the rechargeable lithium batteries must preclude the 
occurrence of self-sustaining, uncontrolled increases in temperature or 
    (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 not shown to be extremely remote, may accumulate in hazardous 
quantities within the airplane.
    (5) Installations of rechargeable lithium batteries must meet the 
requirements of Sec.  23.863(a) through (d) at 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 at amendment 23-49 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 
    (8) Rechargeable lithium battery installations must have--
    i. A system to automatically control the charging rate of the 
battery to prevent battery overheating and overcharging; and either
    ii. 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
    iii. 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 
(see note 1) of the aircraft.

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

    (10) The Instructions for Continued Airworthiness (ICA) required by 
Sec.  23.1529 must contain maintenance requirements (see note 2) to 
assure that the battery has been sufficiently charged (see note 3) 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 (see note 4) 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: Maintenance requirements include procedures that--

    (a) Check battery capacity, charge degradation at manufacturers 
recommended inspection intervals.
    (b) Replace batteries at manufacturers recommended replacement 
schedule/time to prevent age related degradation.

    Note 3: 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: Replacement battery in spares storage may be subject to 
prolonged storage at a low state of charge.

    Issued in Kansas City, Missouri on April 18, 2017.
Mel Johnson,
Acting Manager, Small Airplane Directorate, Aircraft Certification 
[FR Doc. 2017-08234 Filed 4-21-17; 8:45 am]