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.

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REGISTER issue of each week.

Rules and Regulations Federal Register

1591 

Vol. 79, No. 6 

Thursday, January 9, 2014 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 25 

[Docket No. FAA–2013–0763; Special 

Conditions No. 25–514–SC] 

Special Conditions: Learjet Model 35, 

35A, 36, and 36A Airplanes; 

Rechargeable Lithium-Ion Batteries 

and Battery Systems 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 

ACTION: Final special conditions. 

SUMMARY: These special conditions are 

issued for the Learjet Model 35, 35A, 36, 

and 36A airplanes. These airplanes, as 

modified by Peregrine, 13000 E. Control 

Tower Road, Unit K–4, Englewood, CO, 

80112, will have a novel or unusual 

design feature associated with 

rechargeable lithium-ion batteries and 

battery systems. These batteries have 

certain failure, operational, and 

maintenance characteristics that differ 

significantly from those of the nickelcadmium and lead-acid rechargeable 

batteries currently approved for 

installation on large transport-category 

airplanes. 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 Date: February 10, 

2014. 

FOR FURTHER INFORMATION CONTACT: 

Nazih Khaouly, FAA, 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: 

Background 

On June 29, 2012, Peregrine applied 

for a supplemental type certificate for 

installing equipment that uses 

rechargeable lithium-ion battery systems 

in Learjet Model 35, 35A, 36, and 36A 

airplanes. The Learjet Model 35, 35A, 

36, and 36A airplanes are small 

transport-category airplanes powered by 

two turbojet engines, with maximum 

takeoff weights of up to 18,000 pounds. 

These airplanes operate with a two-pilot 

crew and can seat up to eight 

passengers. The Learjet Model 35, 35A, 

36, and 36A airplanes are powered by 

two Garrett TF731–2–2B engines, and 

are equipped with an emergency power 

supply and software-configurable 

avionics. 

Existing airworthiness regulations did 

not anticipate the use of lithium-ion 

batteries and battery systems on aircraft. 

Lithium-ion batteries and battery 

systems have new hazards that were not 

contemplated when the existing 

regulations were issued. In Title 14, 

Code of Federal Regulations (14 CFR) 

25.1353, the FAA provided an 

airworthiness standard for lead-acid 

batteries and nickel-cadmium batteries. 

These special conditions provide an 

equivalent level of safety as that of the 

existing regulation. The current 

regulations are not adequate for 

rechargeable lithium-battery and battery 

system installations. Additional 

lithium-battery and battery system 

special conditions are required to 

ensure the same level of safety as set 

forth by the existing regulation intended 

for other battery technology. 

Type Certification Basis 

Under the provisions of 14 CFR 21.17, 

Peregrine must show that the Learjet 

Model 35, 35A, 36, and 36A airplanes, 

as changed, continue to meet the 

applicable provisions of the regulations 

incorporated by reference in Type 

Certificate No. A10CE or the applicable 

regulations in effect on the date of 

application for the change. The 

regulations incorporated by reference in 

the type certificate are commonly 

referred to as the ‘‘original type 

certification basis.’’ The regulations 

incorporated by reference in Type 

Certificate No. A10CE are as follows: 

Title 14, Code of Federal Regulations 

part 25, effective February 1, 1965, as 

amended by Amendments 25–1, 25–2, 

25–4, 25–7, 25–18, and § 25.571(d) of 

Amendment 25–10; Special Conditions 

set forth in FAA letter to Learjet dated 

March 1, 1967; Special Conditions No. 

25–50–CE–6 dated April 18, 1973, and 

Amendment 1 dated September 18, 

1973. The certification basis for Models 

35A and 36A also includes Special 

Conditions No. 25–72–CE–8 dated 

November 3, 1976, and Amendment 1 

dated March 14, 1978. The certification 

basis for Model 35A, in addition to the 

basis listed above, includes Special 

Conditions 25–ANM–28 dated May 3, 

1989. In addition, the certification basis 

includes certain later amended sections 

of the applicable part 25 regulations that 

are not relevant to these special 

conditions. 

If the regulations incorporated by 

reference do not provide adequate 

standards regarding the change, the 

applicant must comply with certain 

regulations in effect on the date of 

application for the change. 

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 Learjet Model 35, 35A, 36, and 

36A airplanes because of a novel or 

unusual design feature, special 

conditions are prescribed under the 

provisions of § 21.16. 

Special conditions are initially 

applicable to the model for which they 

are issued. Should the applicant apply 

for a supplemental type certificate to 

modify any other model included on the 

same type certificate, to incorporate the 

same or similar novel or unusual design 

feature, the special conditions would 

also apply to the other model under 

§ 21.101. 

In addition to the applicable 

airworthiness regulations and special 

conditions, the Learjet Model 35, 35A, 

36, and 36A airplanes 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. 

The FAA issues special conditions, as 

defined in 14 CFR 11.19, in accordance 

with § 11.38, and they become part of 

the type-certification basis under 

§ 21.101. 


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1592 Federal Register / Vol. 79, No. 6 / Thursday, January 9, 2014 / Rules and Regulations 

Novel or Unusual Design Features 

The Learjet Model 35, 35A, 36, and 

36A airplanes will incorporate the 

following novel or unusual design 

features: A Mid-Continent MD835–5 

Emergency Power Supply that uses a 

rechargeable lithium-ion battery and 

battery system. Lithium-ion batteries 

and battery systems have certain failure, 

operational, and maintenance 

characteristics that differ significantly 

from those of the nickel-cadmium and 

lead-acid rechargeable batteries. 

Rechargeable lithium-ion batteries and 

battery systems are considered to be a 

novel or unusual design feature in 

transport-category airplanes, with 

respect to the requirements in 14 CFR 

25.1353. 

Discussion 

The current regulations governing 

installation of batteries in large 

transport-category airplanes were 

derived from Civil Air Regulations 

(CAR) part 4b.625(d) as part of the recodification of CAR 4b that established 

14 CFR part 25 in February 1965. The 

new battery requirements, 

§ 25.1353(c)(1) through (c)(4), basically 

reworded the CAR requirements. 

Increased use of nickel-cadmium 

batteries in small airplanes resulted in 

increased incidents of battery fires and 

failures which led to additional 

rulemaking affecting large transportcategory airplanes as well as small 

airplanes. On September 1, 1977 and 

March 1, 1978, the FAA issued 

§ 25.1353(c)(5) and (c)(6), respectively, 

governing nickel-cadmium battery 

installations on large transport-category 

airplanes. 

The proposed use of lithium-ion 

batteries and battery systems for 

equipment and systems on the Learjet 

Model 35, 35A, 36, and 36A airplanes 

has prompted the FAA to review the 

adequacy of these existing regulations. 

Our review indicates that the existing 

regulations do not adequately address 

several failure, operational, and 

maintenance characteristics of lithiumion batteries and battery systems that 

could affect the safety and reliability of 

the MD835–5 Emergency Power Supply 

installations. 

At present, commercial aviation has 

limited experience with use of 

rechargeable lithium-ion batteries and 

battery systems in applications 

involving commercial aviation. 

However, other users of this technology, 

ranging from wireless telephone 

manufacturers to the electric-vehicle 

industry, have noted potential hazards 

with lithium-ion batteries and battery 

systems. These problems include 

overcharging, over-discharging, and 

flammability of cell components. 

1. Overcharging 

In general, lithium-ion batteries and 

battery systems 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. This condition 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 lithiumion batteries and battery systems, 

beyond a certain voltage (typically 2.4 

volts), 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 flightcrews as a 

means of checking battery status—a 

problem shared with nickel-cadmium 

batteries. 

3. Flammability of Cell Components 

Unlike nickel-cadmium and lead-acid 

batteries, some types of lithium-ion 

batteries and battery systems use liquid 

electrolytes that are flammable. The 

electrolyte can serve as a source of fuel 

for an external fire, if there is a breach 

of the battery container. 

The problems lithium-ion battery and 

battery-system users experience raise 

concern about the use of these batteries 

in commercial aviation. The intent of 

the special conditions is to establish 

appropriate airworthiness standards for 

lithium-ion battery installations in the 

Learjet Model 35, 35A, 36, and 36A 

airplanes and to ensure, as required by 

§§ 25.1309 and 25.601, that these 

lithium-ion batteries and battery 

systems are not hazardous or unreliable. 

To address these concerns, these special 

conditions adopt the following 

requirements: 

• Those sections of 14 CFR 25.1353 

that are applicable to lithium-ion 

batteries. 

• The flammable fluid fire protection 

requirements of 14 CFR 25.863. In the 

past, this rule was not applied to 

batteries of transport category airplanes, 

since the electrolytes used in lead-acid 

and nickel-cadmium batteries are not 

flammable. 

• New requirements to address the 

hazards of overcharging and overdischarging that are unique to lithium 

ion batteries. 

• New maintenance requirements to 

ensure that batteries used as spares are 

maintained in an appropriate state of 

charge. 

These special conditions are similar 

to lithium-ion batteries and battery 

systems special conditions adopted for 

numerous other aircraft, including 

Boeing Model 787 (72FR57842; October 

11, 2007). 

Discussion of Comments 

Notice of proposed special conditions 

no. 25–13–07–SC for the Peregrine 

modifications to the Learjet Model 35, 

35A, 36, and 36A airplanes was 

published in the Federal Register on 

October 22, 2013 (78 FR 62495). No 

comments were received, and the 

special conditions are adopted as 

proposed. 

Applicability 

As discussed above, these special 

conditions are applicable to the Learjet 

Model 35, 35A, 36, and 36A airplanes. 

Should Peregrine apply at a later date 

for a supplemental type certificate to 

modify any other model included on 

Type Certificate No. A10CE, to 

incorporate 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 the Learjet 

Model 35, 35A, 36, and 36A airplanes. 

It is not a rule of general applicability 

and it affects only the applicant who 

applied to the FAA for approval of these 

features on the airplane. 

List of Subjects in 14 CFR Part 25 

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 Special Conditions 

Accordingly, pursuant to the 

authority delegated to me by the 

Administrator, the following special 

conditions are issued as part of the typecertification basis for the Learjet Model 

35, 35A, 36, and 36A airplanes modified 

by Peregrine. 

These special conditions require that 

(1) all characteristics of the rechargeable 

lithium-ion batteries and battery 

systems, and their installation, that 


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Federal Register / Vol. 79, No. 6 / Thursday, January 9, 2014 / Rules and Regulations 1593 

could affect safe operation of the Learjet 

Model 35, 35A, 36, and 36A airplanes, 

are addressed, and (2) appropriate 

Instructions for Continued 

Airworthiness, which include 

maintenance requirements, are 

established to ensure the availability of 

electrical power, when needed, from the 

batteries. 

In lieu of the requirements of 14 CFR 

25.1353(b)(1) through (b)(4) at 

Amendment 25–113, the following 

special conditions apply. Rechargeable 

lithium-ion batteries and battery 

systems on Learjet Model 35, 35A, 36, 

and 36A airplanes must be designed and 

installed as follows: 

1. Safe cell temperatures and 

pressures must be maintained during 

any foreseeable charging or discharging 

condition, and during any failure of the 

charging or battery monitoring system 

not shown to be extremely remote. The 

rechargeable lithium-ion batteries and 

battery systems must preclude 

explosion in the event of those failures. 

2. Design of the rechargeable lithiumion batteries and battery systems must 

preclude the occurrence of selfsustaining, uncontrolled increases in 

temperature or pressure. 

3. No explosive or toxic gases emitted 

by any rechargeable lithium-ion 

batteries and battery systems in normal 

operation, or as the result of any failure 

of the battery charging system, 

monitoring system, or battery 

installation that is not shown to be 

extremely remote, may accumulate in 

hazardous quantities within the 

airplane. 

4. Installations of rechargeable 

lithium-ion batteries and battery 

systems must meet the requirements of 

§ 25.863(a) through (d). 

5. No corrosive fluids or gases that 

may escape from any lithium-ion 

batteries and battery systems may 

damage surrounding structure or any 

adjacent systems, equipment, or 

electrical wiring of the airplane in such 

a way as to cause a major or more severe 

failure condition, in accordance with 

§ 25.1309 (b) and applicable regulatory 

guidance. 

6. Each lithium-ion battery and 

battery system must have provisions to 

prevent any hazardous effect on 

structure or essential systems caused by 

the maximum amount of heat the 

battery can generate during a short 

circuit of the battery or of its individual 

cells. 

7. Rechargeable lithium-ion batteries 

and battery systems must have a system 

to automatically control the charging 

rate of the battery, 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 rechargeable lithium-ion 

batteries and battery systems, the 

function of which are 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 state-of-charge of the 

batteries has fallen below levels 

considered acceptable for dispatch of 

the airplane. 

9. The Instructions for Continued 

Airworthiness required by § 25.1529 

must contain maintenance requirements 

to assure that the lithium-ion batteries 

are sufficiently charged at appropriate 

intervals specified by the battery 

manufacturer and the equipment 

manufacturer of the rechargeable 

lithium-ion battery or rechargeable 

lithium-ion battery system. This is 

required to ensure that rechargeable 

lithium-ion batteries and battery 

systems will not degrade below 

specified ampere-hour levels sufficient 

to power the aircraft system, for 

intended applications. The Instructions 

for Continued Airworthiness must also 

contain procedures for the maintenance 

of batteries in spares storage to prevent 

the replacement of batteries with 

batteries that have experienced 

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. Precautions 

should be included in the Instructions 

for Continued Airworthiness 

maintenance instructions to prevent 

mishandling of the rechargeable 

lithium-ion batteries and battery 

systems, which could result in shortcircuit or other unintentional impact 

damage caused by dropping or other 

destructive means. 

Note 1: The term ‘‘sufficiently charged’’’ 

means that the battery will retain enough of 

a charge, expressed in ampere-hours, to 

ensure that the battery cells will not be 

damaged. A battery cell may be damaged by 

lowering the charge below a point where the 

battery experiences 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 2: These special conditions are not 

intended to replace § 25.1353(b) at 

Amendment 25–113 in the certification basis 

for Learjet Model 35, 35A, 36, and 36A 

airplanes. These special conditions apply 

only to rechargeable lithium-ion batteries and 

battery systems and their installations. The 

requirements of § 25.1353(b) at Amendment 

25–113 remain in effect for batteries and 

battery installations on Learjet Model 35, 

35A, 36, and 36A airplanes that do not use 

rechargeable lithium-ion batteries. 

Issued in Renton, Washington, on 

December 31, 2013. 

Angelos Xidias, 

Acting Manager, Transport Airplane 

Directorate, Aircraft Certification Service. 

[FR Doc. 2014–00172 Filed 1–8–14; 8:45 am] 

BILLING CODE 4910–13–P 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Part 52 

[EPA–R04–OAR–2013–0440; FRL–9905–13– 

Region 4] 

Approval and Promulgation of 

Implementation Plans; Tennessee; 

Bristol; 2010 Lead Base Year 

Emissions Inventory and Conversion 

of Conditional Approvals for 

Prevention of Significant Deterioration 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Final rule. 

SUMMARY: The Environmental Protection 

Agency (EPA) is approving the Lead 

2010 base year emissions inventory 

State Implementation Plan (SIP) 

revision submitted by the State of 

Tennessee, through the Tennessee 

Department of Environment and 

Conservation (TDEC) on April 11, 2013. 

The emissions inventory was submitted 

to meet the requirements of the Clean 

Air Act (CAA or Act) for the Bristol 

2008 Lead National Ambient Air 

Quality Standards (NAAQS) 

nonattainment area (hereafter also 

referred to as the ‘‘Bristol Area’’ or 

‘‘Area’’). Additionally, EPA is 

converting conditional approvals to full 

approvals for Tennessee’s 1997 annual 

fine particulate matter (PM2.5) NAAQS, 

2006 24-hour PM2.5 NAAQS and 2008 8- 

hour ozone NAAQS infrastructure SIPs 

as they relate to adequate provisions 

prohibiting emissions that interfere with 

any other State’s required measures to 

prevent significant deterioration of its 

air quality. EPA conditionally approved 

these portions of Tennessee’s 

infrastructure SIPs for these NAAQS on 

March 6, 2013, and March 26, 2013. 

Tennessee has since met the obligations 


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