2126 Federal Register / Vol. 89, No. 9 / Friday, January 12, 2024 / Rules and Regulations 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 25 

[Docket No. FAA–2022–0205; Special 

Conditions No. 25–844–SC] 

Special Conditions: Lufthansa Tecknik 

AG, Airbus Models A319–133 and 

A321–200 Series Airplanes; 

Supercapacitor Systems and 

Installation 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 

ACTION: Final special conditions. 

SUMMARY: These special conditions are 

issued for the Airbus Model A319–133 

and A321–200 series airplanes. These 

airplanes, as modified by Lufthansa 

Tecknik AG (Lufthansa), 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 the 

installation of an uninterruptible power 

supply (UPS) system based on 

supercapacitor technology. The current 

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 January 12, 2024. 

FOR FURTHER INFORMATION CONTACT: 

Daniel Poblete, Electrical Systems, AIR– 

626A, Technical Policy Branch, Policy 

and Standards Division, Aircraft 

Certification Service, Federal Aviation 

Administration, 3960 Paramount Blvd., 

Suite 100, Lakewood, CA 90712–4137; 

telephone and fax (562) 627–5335; email 

daniel.d.poblete@faa.gov. 

SUPPLEMENTARY INFORMATION: 

Background 

On February 17, 2021, Lufthansa 

applied for a supplemental type 

certificate for the installation of a UPS 

system in the Model A319–133 and 

A321–200 series airplanes. The Airbus 

Model A319–133 and A321–200 series 

airplanes are twin-engine, transport 

category airplanes. The Airbus Model 

A319–133 airplane has a maximum 

passenger seating capacity of 160, and a 

maximum takeoff weight of 154,322 

pounds. The Airbus Model A321–200 

airplane has a maximum passenger 

seating capacity 230, and a maximum 

takeoff weight of 213,848 pounds. 

Type Certification Basis 

Under the provisions of title 14, Code 

of Federal Regulations (14 CFR) 21.101, 

Lufthansa must show that the Model 

A319–133 and A321–200 series 

airplanes, as changed, continue to meet 

the applicable provisions of the 

regulations listed in Type Certificate No. 

A28NM or the applicable regulations in 

effect on the date of application for the 

change, except for earlier amendments 

as agreed upon by the FAA. 

If the Administrator finds that the 

applicable airworthiness regulations 

(e.g., 14 CFR part 25) do not contain 

adequate or appropriate safety standards 

for the Airbus Model A319–133 and 

A321–200 series 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 novel or unusual design feature, 

these special conditions would also 

apply to the other model under § 21.101. 

In addition to the applicable 

airworthiness regulations and special 

conditions, the Airbus Model A319–133 

and A321–200 series 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. 

Novel or Unusual Design Features 

The Airbus Model A319–133 and 

A321–200 series airplanes will 

incorporate the following novel or 

unusual design features: 

This design feature for this 

installation of a UPS system is based on 

supercapacitor technology. 

Discussion 

Currently, there are no regulatory or 

industry standards for supercapacitors 

and their installation on transport 

category airplanes. Supercapacitors are 

used to provide power to non-essential 

cabin equipment when the normal 

power source is interrupted for a short 

period of time. In this design, the 

supercapacitor UPS system will allow 

connected equipment to be provided 

back-up power if normal electrical 

power source is interrupted, and remain 

operational such as during power 

transfers as well as provide transient 

voltage surge suppression should 

harmful high voltage transients occur. 

The UPS is only used for systems not 

critical to continued safe flight and 

landing. 

Since the supercapacitor is being used 

as a high-capacity electrical storage 

device and functions similarly to 

rechargeable batteries, the special 

conditions used for lithium batteries are 

appropriate for supercapacitor 

installations and the hazardous 

conditions that could be presented. 

These special conditions are necessary 

to assist in the testing and installation 

of this supercapacitor on the aircraft. 

Special condition 1 requires that the 

supercapacitor installation be designed 

to preclude propagation of a thermal 

event, such as self-sustained, 

uncontrolled increases in temperature 

or pressure. Special condition 1 is 

intended to ensure that the 

supercapacitor system is 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 supercapacitor designer. 

Therefore, other special conditions are 

intended to protect the airplane and its 

occupants if other failures occur. 

Special conditions 2, 6, 8, and 9 are 

self-explanatory. 

Special condition 3 makes it clear that 

the flammable fluid fire protection 

requirements of § 25.863 apply to 

supercapacitor installations. Section 

25.863 is applicable to areas of the 

airplane that could be exposed to 

flammable fluid leakage from airplane 

systems. Supercapacitors may contain 

an electrolyte that is a flammable fluid. 

Special condition 4 requires that each 

supercapacitor installation not damage 

surrounding structure or adjacent 

systems, equipment, or electrical wiring 

interconnection system (EWIS) 

components from corrosive fluids or 

gases that may escape in such a way as 

to cause a hazardous condition. 

While special condition 4 addresses 

corrosive fluids and gases, special 

condition 5 addresses heat. Special 

condition 5 requires that each 

supercapacitor installation have 

provisions to prevent any hazardous 

effect on surrounding structure or 

adjacent systems, equipment, or EWIS 

components, caused by the maximum 

amount of heat the supercapacitor 

installation can generate due to any 

failure of the supercapacitor installation 

or any of the individual supercapacitors. 

The means of meeting special 

conditions 4 and 5 may be the same, but 

the requirements are independent and 

address different hazards. 


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Federal Register / Vol. 89, No. 9 / Friday, January 12, 2024 / Rules and Regulations 2127 

Special condition 7 requires that 

supercapacitor be disconnected or 

otherwise removed from its charging 

source without the need for crew 

intervention should the supercapacitor 

become overheated or fail in a manner 

that may create a safety hazard. This 

requirement applies to all 

supercapacitor installations and is not 

limited to those whose proper 

functioning is required for the safe 

operation of the airplane. 

The 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 

The FAA issued Notice of Proposed 

Special Conditions No. 25–22–02–SC 

for the Airbus Model A319–133 and 

A321–200 series airplanes, which was 

published in the Federal Register on 

June 1, 2023 (88 FR 35781). The FAA 

received one comment from The Boeing 

Company (Boeing). 

Boeing recommended the FAA add a 

definition of what constitutes a 

supercapacitor and high-capacity 

electrical storage device and to include 

their thresholds such as capacity, 

voltage, and dialectic strength. Boeing 

stated that this clarification of 

supercapacitor terminology will avoid 

any ambiguity and confusion when 

applying special conditions and their 

applicability, specifically with the 

inapplicability to small capacitors that 

are used on various electrical systems 

used in electronics. 

The FAA acknowledges Boeing’s 

recommendation that adding a 

definition of what constitutes a 

supercapacitor is important for 

clarification and to ensure these special 

conditions’ inapplicability to small 

capacitors used in various electrical 

systems in aviation electronics. 

However, the FAA declines to create a 

definition for supercapacitors through 

special conditions. Currently, the FAA 

is not aware of an industry standard 

regarding the design and installation of 

supercapacitors. With no supercapacitor 

industry standard currently available, 

the similarity of the function of the 

supercapacitor closely relates to the 

rechargeable lithium batteries. 

Therefore, the special conditions used 

for lithium batteries are being used for 

this supercapacitor installation. The 

applicant and the FAA will review the 

design and installation of the 

supercapacitor to ensure these special 

conditions will apply only to 

supercapacitors used as energy storage 

devices similar to rechargeable lithium 

batteries. 

Applicability 

As discussed above, these special 

conditions are applicable to the Airbus 

Model A319–133 and A321–200 series 

airplanes. Should Lufthansa apply at a 

later date for a change to the 

supplemental type certificate to include 

another model incorporating the same 

novel or unusual design feature 

included on Type Certificate No. 

A28NM, these special conditions would 

apply to that model as well. 

Under standard practice, the effective 

date of final special conditions would 

be 30 days after the date of publication 

in the Federal Register. However, as the 

certification date for the Airbus Model 

A319–133 and A321–200 series 

airplanes is imminent, the FAA finds 

that good cause exists to make these 

special conditions effective upon 

publication. 

Conclusion 

This action affects only a certain 

novel or unusual design feature on 

Airbus Models A319–133 and A321–200 

series 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. 

List of Subjects in 14 CFR Part 25 

Aircraft, Aviation safety, Reporting 

and recordkeeping requirements. 

Authority Citation 

The authority citation for these 

special conditions is as follows: 

Authority: 49 U.S.C. 106(f), 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 type 

certification basis for Airbus Model 

A319–133 and A321–200 series 

airplanes, as modified by Lufthansa 

Technik AG. Each supercapacitor 

installation must: 

1. Be designed to preclude the 

occurrence of uncontrolled increases in 

temperature or pressure under all 

foreseeable operating and failure 

conditions to prevent fire and 

explosion. 

2. Not emit explosive or toxic gasses, 

in normal operation or as the result of 

its failure that may accumulate in 

hazardous quantities in any area of the 

airplane. 

3. Meet the requirements of § 25.863. 

4. Not damage surrounding structure 

or adjacent systems, equipment, or 

electrical wiring interconnection system 

(EWIS) components from corrosive 

fluids or gases that may escape to cause 

a hazardous condition. 

5. Have provisions to prevent any 

hazardous effect on surrounding 

structure or adjacent systems, 

equipment, or EWIS components, 

caused by the maximum amount of heat 

it can generate during any failure 

including any individual 

supercapacitors. 

6. Have a means to prevent 

overheating or overcharging of the 

supercapacitor. 

7. Have a means to automatically 

disconnect it from its charging source in 

the event of an over-temperature 

condition or failure. 

8. Have a monitoring and alerting 

feature that alerts the flightcrew when 

the capacity has fallen below acceptable 

levels if its function is required for safe 

operation of the airplane. The flightcrew 

alerting must be in accordance with the 

requirements of § 25.1322. 

9. Have a means to prevent 

insufficient charging if required for safe 

operation of the airplane. 

Note: A supercapacitor installation consists 

of the supercapacitor(s) and any protective, 

monitoring and alerting circuitry or hardware 

inside or outside of the supercapacitor. This 

includes EWIS components as defined by 

§ 25.1701. It also includes any venting or 

cooling system and packaging. For the 

purpose of these special conditions, a 

supercapacitor and the supercapacitor 

installation is referred to as a supercapacitor. 

Issued in Kansas City, Missouri, on January 

8, 2024. 

Patrick R. Mullen, 

Manager, Technical Policy Branch, Policy and 

Standards Division, Aircraft Certification 

Service. 

[FR Doc. 2024–00484 Filed 1–11–24; 8:45 am] 

BILLING CODE 4910–13–P 

DEPARTMENT OF THE TREASURY 

Internal Revenue Service 

26 CFR Part 1 

[TD 9986] 

RIN 1545–BQ57 

Corporate Bond Yield Curve for 

Determining Present Value 

AGENCY: Internal Revenue Service (IRS), 

Treasury. 

ACTION: Final regulations. 

SUMMARY: This document sets forth final 

regulations specifying the methodology 


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