[Federal Register Volume 73, Number 232 (Tuesday, December 2, 2008)]
[Proposed Rules]
[Pages 73195-73197]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E8-28491]


 ========================================================================
 Proposed Rules
                                                 Federal Register
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 This section of the FEDERAL REGISTER contains notices to the public of 
 the proposed issuance of rules and regulations. The purpose of these 
 notices is to give interested persons an opportunity to participate in 
 the rule making prior to the adoption of the final rules.
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  Federal Register / Vol. 73, No. 232 / Tuesday, December 2, 2008 / 
Proposed Rules  

[[Page 73195]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 23

[Docket No. CE291; Notice No. 23-08-05-SC]


Special Conditions: Spectrum Aeronautical, LLC Model 40; Lithium 
Polymer Battery Installation

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed special conditions.

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SUMMARY: This action proposes special conditions for the Spectrum 
Aeronautical, LLC Model 40 (S-40) airplane. This airplane will have a 
novel or unusual design feature associated with the installation of 
lithium polymer (Li-Poly) batteries for emergency, main, and auxiliary 
power unit (APU) applications. The applicable airworthiness regulations 
do not contain adequate or appropriate safety standards for this design 
feature. These proposed 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: We must receive your comments by January 2, 2009.

ADDRESSES: You must mail two copies of your comments to Federal 
Aviation Administration, Regional Counsel, ACE-7, Attention: Rules 
Docket Clerk, Docket No. CE291, Room 506, 901 Locust, Kansas City, 
Missouri 64106. You may deliver two copies to the Small Airplane 
Directorate at the above address. You must mark your comments: Docket 
No. CE291. You may inspect comments in the Rules Docket weekdays, 
except Federal holidays, between 7:30 a.m. and 4 p.m.

FOR FURTHER INFORMATION CONTACT: Jim Brady, Aerospace Engineer, 
Standards Office (ACE-111), Small Airplane Directorate, Aircraft 
Certification Service, Federal Aviation Administration, 901 Locust, 
Room 301, Kansas City, Missouri 64106; telephone (816) 329-4132.

SUPPLEMENTARY INFORMATION:

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 file in the docket all comments we receive, as well as a 
report summarizing each substantive public contact with FAA personnel 
concerning these special conditions. You may inspect the docket before 
and after the comment closing date. If you wish to review the docket in 
person, go to the address in the ADDRESSES section of this preamble 
between 7:30 a.m. and 4 p.m., Monday through Friday, except Federal 
holidays.
    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.
    If you want the FAA to acknowledge receipt of your comments on this 
proposal, include with your comments a pre-addressed, stamped postcard 
on which the docket number appears. We will stamp the date on the 
postcard and mail it back to you.

Background

    On November 21, 2007, Spectrum Aeronautical, LLC applied for a type 
certificate for their new model 40 airplane. The model 40 (S-40) 
airplane, is a 2+9 (pilots + passengers) conventionally configured low 
wing normal category twin-engine jet airplane manufactured primarily 
from advanced carbon fiber composite materials. The model S-40 is 
designed to be certified for a single pilot operation for day, night, 
VFR, IFR and flight into known icing operations at altitudes up to 
45,000 feet. The company will show compliance with Reduced Vertical 
Separation Minimums (RVSM) requirements. Spectrum proposes to utilize 
lithium polymer (Li-Poly) batteries for emergency, main, and auxiliary 
power unit (APU) on the model S-40 airplane.

Type Certification Basis

    Under the provisions of 14 CFR part 21, Sec.  21.17, Spectrum 
Aeronautical, LLC must show that the model S-40 meets the applicable 
provisions of part 23, as amended by Amendments 23-1 through 23-57 
thereto.
    In addition, the certification basis includes certain special 
conditions, and exemptions that are not relevant to these proposed 
special conditions.
    In addition to the applicable airworthiness regulations and special 
conditions, the S-40 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 and the FAA must issue a finding of 
regulatory adequacy under Sec.  611 of Public Law 92-574, the ``Noise 
Control Act of 1972.''
    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 model S-40 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.  21.17(a)(2).
    Special conditions are initially applicable to the 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 or similar 
novel or unusual design feature, the special conditions would also 
apply to the other model under Sec.  21.101.

Novel or Unusual Design Features

    The Spectrum S-40 will incorporate the following novel or unusual 
design features: Spectrum proposes to utilize lithium polymer (Li-Poly) 
batteries for emergency, main, and auxiliary power unit (APU) on the 
Spectrum S-40 airplane model. This type of battery possesses certain 
failure and operational characteristics, and maintenance requirements 
that differ significantly from that of the nickel cadmium (Ni-Cd) and 
lead acid rechargeable batteries currently approved for installation in 
small airplanes. Current regulations in 14 CFR part 23 do not address

[[Page 73196]]

installation of Li-Poly batteries. This special condition is being 
proposed to require that all characteristics of the Li-Poly battery and 
its installation that could affect safe operation of the Spectrum S-40 
airplane are addressed, along with establishing that appropriate 
maintenance requirements must be provided to ensure electrical power is 
available from the batteries when needed.

Discussion

    The applicable part 21 and part 23 airworthiness regulations 
governing the installation of batteries in general aviation airplanes, 
including part 23, Sec.  23.1353 were derived from Civil Air 
Regulations (CAR 3) as part of the recodification that established 
Federal Aviation Regulation 14 CFR part 23. The battery requirements, 
which were identified as 14 CFR part 23, Sec.  23.1353, were basically 
a rewording of the CAR requirements that did not add any substantive 
technical requirements. An increase in incidents involving battery 
fires and failures that accompanied the increased use of Nickel-Cadmium 
(Ni-Cd) batteries in airplanes resulted in rulemaking activities on the 
battery requirements for business jet and commuter category airplanes. 
These regulations were incorporated into 14 CFR part 23, Sec.  
23.1353(f) and (g), which apply only to Ni-Cd battery installations.
    The proposed use of Li-Poly batteries on the Spectrum model S-40 
airplane has prompted the FAA to review the adequacy of the existing 
battery regulations with respect to that chemistry. As the result of 
this review, the FAA has determined that the existing regulations do 
not adequately address several failure, operational, and maintenance 
characteristics of Li-Poly batteries that could affect safety of the 
battery installation and the reliability of the Spectrum model S-40 
airplane electrical power supply.
    Li-Poly batteries in general are significantly more susceptible to 
internal failures that can result in self-sustaining increases in 
temperature and pressure (i.e. thermal runaway) than their Ni-Cd and 
lead-acid counterparts. This is especially true for overcharging a Li-
Poly, which will likely result in explosion, fire, or both. Certain 
types of Li-Poly batteries pose a potential safety problem because of 
the instability and flammability of the organic electrolyte employed by 
the cells of those batteries. The severity of thermal runaway increases 
with increasing battery capacity due to the higher amount of 
electrolyte in large batteries.
    Discharge of some versions of the Li-Poly cell beyond a certain 
voltage below 3.0 volts will subsequently no longer accept a charge. 
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.
    Unlike Ni-Cd and lead-acid cells, some types of Li-Poly cells 
employ electrolytes that are known to be flammable. This material can 
serve as a source of fuel for an external fire in the event of a breach 
of the cell container.
    The intent of the proposed special condition is to establish 
appropriate airworthiness standards for Li-Poly battery installations 
in the Spectrum model 40 airplane, and to ensure, as required by 14 CFR 
part 23, Sec.  23.601, that these battery installations do not possess 
hazardous or unreliable design characteristics. The proposed special 
condition adopts the following requirements as a means of addressing 
these concerns:
     Inclusion of those sections of 14 CFR part 23, Sec.  
23.1353 that are applicable to Li-Poly batteries.
     Inclusion of the flammable fluid fire protection 
requirements of 14 CFR part 23, Sec.  23.863. In the past, this rule 
was not applied to the batteries of business jet or commuter category 
airplanes since the electrolytes utilized in lead-acid and Ni-CD 
batteries are not considered to be flammable.
     Addition of new requirements to address the potential 
hazards of overcharging and overdischarging that are unique to Li-Poly 
battery designs.
    Addition of maintenance requirements to ensure that batteries used 
as spares are maintained in an appropriate state of charge (SOC).

Applicability

    As discussed above, these special conditions are applicable to the 
Spectrum model S-40. Should Spectrum Aeronautical, LLC apply at a later 
date for a change to the type certificate to include another model 
incorporating the same novel or unusual design feature, the special 
conditions would apply to that model as well.

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 23

    Aircraft, Aviation safety, Reporting and recordkeeping 
requirements.

    The authority citation for these special conditions is as follows:

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

The Proposed Special Conditions

    Accordingly, the Federal Aviation Administration (FAA) proposes the 
following special conditions as part of the type certification basis 
for Spectrum Aeronautical, LLC model S-40 airplanes.

Spectrum Aeronautical, LLC Model 40 Lithium Polymer Battery 
Installation

    In lieu of the requirements of 14 CFR part 23, Sec.  23.1353 (a) 
through (e), lithium polymer batteries and battery installations on the 
Spectrum S-40 airplane must be designed and installed as follows:
    (1) Safe cell temperatures and pressures must be maintained during 
any probable charging or discharging condition, or during any failure 
of the charging or battery monitoring system not shown to be extremely 
remote. The Li-Poly battery installation must be designed to preclude 
explosion or fire in the event of those failures.
    (2) Li-Poly batteries must be designed to preclude the occurrence 
of self-sustaining, uncontrolled increases in temperature or pressure.
    (3) No explosive or toxic gasses emitted by any Li-Poly battery in 
normal operation or as the result of any failure of the battery 
charging or monitoring system, or battery installation not shown to be 
extremely remote, may accumulate in hazardous quantities within the 
airplane.
    (4) Li-Poly batteries that contain flammable fluids must comply 
with the flammable fluid fire protection requirements of 14 CFR part 
23, Sec.  23.863(a) through (d).
    (5) No corrosive fluids or gasses that may escape from any Li-Poly 
battery may damage surrounding airplane structure or adjacent essential 
equipment.
    (6) Each Li-Poly 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.
    (7) Li-Poly battery installations must have a system to control the 
charging rate of the battery automatically, so as to prevent battery 
overheating or overcharging, and
    (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,

[[Page 73197]]

    (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.
    (8) Any Li-Poly battery installation whose function is required for 
safe operation of the airplane, must incorporate a monitoring and 
warning feature that will provide an indication to the appropriate 
flight crewmembers, whenever the capacity and SOC of the batteries have 
fallen below levels considered acceptable for dispatch of the airplane.
    (9) The Instructions for Continued Airworthiness (ICAW) must 
contain recommended manufacturers maintenance and inspection 
requirements to ensure that batteries, including single cells, meet a 
safety function level essential to the aircraft's continued 
airworthiness.
    (i) The ICAW must contain operating instructions and equipment 
limitations in an installation maintenance manual.
    (ii) The ICAW must contain installation procedures and limitation 
in a maintenance manual, sufficient to ensure that cells or batteries, 
when installed according to the installation procedures, still meet 
safety functional levels, essential to the aircraft's continued 
airworthiness. The limitation must identify any unique aspects of the 
installation.
    (iii) The ICAW must contain corrective maintenance procedures to 
functionally check battery capacity at manufacturers' recommended 
inspection intervals.
    (iv) The ICAW must contain scheduled servicing information to 
replace batteries at manufacturers' recommended replacement time.
    (v) The ICAW must contain maintenance inspection requirements to 
visually check for a battery and/or charger degradation.
    (10) Batteries in a rotating stock (spares) that have experienced 
degraded charge retention capability or other damage due to prolonged 
storage must be functionally checked at manufacturers' recommended 
inspection intervals.
    (11) System Safety Assessment process should address the software 
and complex hardware levels for the sensing, monitoring and warning 
systems, if these systems contain complex devices. The functional 
hazard assessment (FHA) for the system is required based on the 
intended functions described. The criticality of the specific functions 
will be determined by the safety assessment process for compliance with 
14 CFR part 23, Sec.  23.1309, and Advisory Circular 23.1309-1C 
contains acceptable means for accomplishing this requirement. For 
determining the failure condition, the criticality of a function will 
include the mitigating factors. The failure conditions must address the 
loss of function and improper operations.
    It should be noted that these special conditions are not intended 
to replace 14 CFR part 23, Sec.  23.1353 in the certification basis of 
the Spectrum model S-40 airplanes. The proposed special conditions 
would apply only to Li-Poly batteries and battery installations. The 
battery requirements of 14 CFR part 23, Sec.  23.1353 would remain in 
effect for batteries and battery installations on the Spectrum airplane 
that do not utilize Li-Poly chemistry.

    Issued in Kansas City, Missouri on November 20, 2008.
John Colomu,
Acting Manager, Small Airplane Directorate, Aircraft Certification 
Service.
 [FR Doc. E8-28491 Filed 12-1-08; 8:45 am]
BILLING CODE 4910-13-P