[Federal Register Volume 74, Number 106 (Thursday, June 4, 2009)]
[Proposed Rules]
[Pages 26818-26820]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E9-12994]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 23

[Docket No. CE296; Notice No. 23-09-02SC]


Special Conditions: Cessna Aircraft Company, Model 525C (CJ4); 
Lithium Ion 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 Cessna 
Aircraft Company, model 525C (CJ4) airplane. This airplane will have a 
novel or unusual design feature associated with the installation of 
lithium ion (Li-ion) batteries. Cessna Aircraft Company proposes to use 
a lithium-ion main battery on the new model 525C (CJ4) commuter 
category airplane for main battery applications, and is also 
considering the use of this technology in several other auxiliary 
battery applications in this airplane. This type of battery possesses 
certain failure, operational characteristics, and maintenance 
requirements that differ significantly from that of the nickel cadmium 
and lead acid rechargeable batteries currently approved in other 
normal, utility, acrobatic, and commuter category airplanes. 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 July 6, 2009.

ADDRESSES: Mail two copies of your comments to Federal Aviation 
Administration, Regional Counsel, ACE-7, Attention: Rules Docket Clerk, 
Docket No. CE296, Room 506, 901 Locust, Kansas City, Missouri 64106. 
You may deliver two copies to the Small Airplane Directorate at the 
above address. Mark your comments: Docket No. CE296. 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: Ervin Dvorak, 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) 329-4123.

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 August 9, 2006, Cessna Aircraft Company applied for an amendment 
to Type Certificate Number A1WI to include the new model 525C (CJ4). 
The model 525C (CJ4), which is a derivative of the model 525B (CJ3) 
currently approved under Type Certificate Number A1WI, is a commuter 
category, low-winged monoplane with ''T'' tailed vertical and 
horizontal stabilizers, retractable tricycle type landing gear and twin 
turbofan engines mounted on the aircraft fuselage. The maximum takeoff 
weight is 16,950 pounds, the VMO/MMO is 305 KIAS/M 0.77 and maximum 
altitude is 45,000 feet. Cessna Aircraft Company proposes to utilize 
lithium Ion (Li-ion) batteries for main battery applications, and is 
considering the use of this technology in several other auxiliary 
battery applications in this airplane.

Type Certification Basis

    Under the provisions of 14 CFR part 21, Sec.  21.101, Cessna 
Aircraft Company must show that the model 525C (CJ4)

[[Page 26819]]

meets the applicable provisions of the requirements incorporated by 
reference in Type Certificate No. A1W1 or 14 CFR part 23, as amended by 
Amendments 23-1 through 23-57 thereto. The regulations incorporated by 
reference in the type certificate are commonly referred to as the 
original type certificate basis.
    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 model 525C (CJ4) 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 525C (CJ4) 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 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

    Cessna Aircraft Company, model 525C (CJ4) will incorporate the 
following novel or unusual design features:
    Cessna Aircraft Company proposes to use lithium ion (Li-ion) 
batteries for main battery applications, and is considering the use of 
this technology in several other auxiliary battery applications on the 
Cessna Aircraft Company, model 525C (CJ4) airplane. 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 installation of Li-ion batteries. This 
special condition is being proposed to require that all characteristics 
of the Li-ion battery and its installation that could affect safe 
operation of the Cessna Aircraft Company, model 525C (CJ4) 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-ion batteries on the Cessna Aircraft 
Company, model 525C (CJ4) 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-ion batteries that 
could affect safety of the battery installation and the reliability of 
the Cessna Aircraft Company, model 525C (CJ4) airplane electrical power 
supply.
    Li-ion 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-
ion, which will likely result in explosion, fire, or both. Certain 
types of Li-ion 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-ion 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-ion battery installations in 
the Cessna Aircraft Company, model 525C (CJ4) 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:
    <bullet> Inclusion of those sections of 14 CFR part 23, Sec.  
23.1353 that are applicable to Li-ion batteries.
    <bullet> 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.
    <bullet> Addition of new requirements to address the potential 
hazards of overcharging and overdischarging that are unique to Li-ion 
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 
Cessna model 525C (CJ4). Should Cessna Aircraft Company 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.

Citation

    The authority citation for these special conditions is as follows:


[[Page 26820]]


    Authority: 49 U.S.C. 106(g), 40113, and 44701; 14 CFR 21.16 and 
21.17; 14 CFR 11.38 and 11.19.

The Proposed Special Conditions

    Accordingly, the Federal Aviation Administration (FAA) proposes the 
following special conditions as part of the type certification basis 
for Cessna Aircraft Company, model 525C (CJ4) airplanes.

Cessna Aircraft Company, Model 525C (CJ4) Lithium Ion Battery 
Installation

    In lieu of the requirements of 14 CFR part 23, Sec.  23.1353(a) 
through (e), lithium ion batteries and battery installations on the 
Cessna Aircraft Company, model 525C (CJ4) 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-ion battery installation must be designed to preclude 
explosion or fire in the event of those failures.
    (2) Li-ion 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-ion 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-ion 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-ion 
battery may damage surrounding airplane structure or adjacent essential 
equipment.
    (6) Each Li-ion 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-ion 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,
    (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-ion 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 23.1309-1D 
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.
    These special conditions are not intended to replace 14 CFR part 
23, Sec.  23.1353 in the certification basis of the Cessna Aircraft 
Company, model 525C (CJ4) airplanes. The proposed special conditions 
would apply only to Li-ion 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 Cessna Aircraft 
Company, model 525C (CJ4) airplane that do not use Li-ion chemistry.

    Issued in Kansas City, Missouri on May 27, 2009.
John Colomy,
Acting Manager, Small Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. E9-12994 Filed 6-3-09; 8:45 am]
BILLING CODE 4910-13-P