2014-23887. Special Conditions: Hawker Beechcraft, Model 400A Airplane, as Modified by Nextant Aerospace; Installed Rechargeable Lithium Batteries and Battery Systems

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Final special condition; request for comments.

SUMMARY:

These special conditions are issued for the Hawker Beechcraft Model No. 400A airplane as modified by Nextant Aerospace. This modification will have a novel or unusual design feature associated with an installed emergency power supply and standby attitude module that use rechargeable lithium batteries and battery systems. 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 October 7, 2014. We must receive your comments by November 21, 2014.

ADDRESSES:

Send comments identified by docket number FAA-2014-0706 using any of the following methods:

• Federal eRegulations Portal: Go to http://www.regulations.gov/​ and follow the online instructions for sending your comments electronically.
• 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.
• Hand Delivery or 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.
• Fax: Fax comments to Docket Operations at 202-493-2251.

Privacy: The FAA will post all comments it receives, without change, to http://www.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.

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 [phone]; facsimile 425-227-1149.

SUPPLEMENTARY INFORMATION:

The FAA has determined that notice of, and opportunity for prior public comment on, these special conditions is impracticable because these procedures would significantly delay issuance of the design approval and thus delivery of the affected aircraft. In addition, 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 publication in the Federal Register.

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 will consider all comments we receive by the closing date for comments. We may change these special conditions based on the comments we receive.

Background

On November 29, 2012, Nextant Aerospace applied for an amendment to supplemental type certificate (STC) ST10959SC to replace the existing nickel-cadmium standby power supplies with new rechargeable lithium battery emergency power supplies and to install a module that uses a rechargeable lithium battery for emergency power back-up on the Hawker Beechcraft Model 400A. The Model 400A is a mid-size, nine (9) passenger maximum business jet powered by two turbo fan engines.

The amendment to STC ST10959SC, Rockwell Collins Proline 21 Instrument Display System, includes the installation of Mid-Continent Instrument Co. MD302 Standby Instrument and TS835 Emergency Power Supplies. It also includes the installation of a Midcontinent MD302 Standby Attitude Module for emergency power back-up, all of which use rechargeable lithium batteries and battery systems.

Rechargeable lithium batteries are a novel or unusual design feature in transport category airplanes. This type of battery has certain failure, operational, and maintenance characteristics that differ significantly from those of the nickel-cadmium and lead-acid rechargeable batteries currently approved for installation on transport category airplanes. Because of rapid improvements in airplane technology, the applicable airworthiness regulations do not contain adequate or appropriate safety standards for this design feature.

Type Certification Basis

Under the provisions of 14 CFR 21.101, Nextant Aerospace must show that the Model 400A, as changed, continues to meet the applicable provisions of the regulations incorporated by reference in STC ST10959SC or the applicable regulations in effect on the date of application for the change. The regulations incorporated by reference in the STC are commonly referred to as the “original type certification basis.” The regulations incorporated by reference in STC ST10959SC are as follows:

The certification basis is 14 CFR part 25 effective February 1, 1965, as amended by 25-1 through 25-40, plus §§ 25.1335, 25.1351(d), 25.1353(c)(5), and 25.1447 at Amendment 25-41; §§ 25.29, 25.255, and 25.1353(c)(6) at Amendment 25-42; §§ 25.361(b) and 25.1329(h) at Amendment 25-46; 14 CFR part 36, effective December 1, 1969, as amended by 36-1 through 36-17; SFAR 27 effective February 1, 1974, as amended by 27-1 through 27-5; and Special Conditions No. 25-ANM-32 dated February 22, 1990, High Altitude Operation, and Special Conditions No. 25-ANM-33 dated June 18, 1990, Lightning and Radio Frequency Energy Protection.

In addition, 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. The FAA has determined that the Model 400A, as modified by STC ST10959SC, must also comply with the following section of part 25 as amended by Amendment 25-1 through 25-123: § 25.1353.

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 Hawker Beechcraft Model 400A because of a novel or unusual design feature, special conditions are prescribed under the provisions of 14 CFR 21.16.

Special conditions are initially applicable to the model for which they are issued. Should the applicant apply for a 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 also apply to the other model.

In addition to the applicable airworthiness regulations and special conditions, the Hawker Beechcraft Model 400A, as modified by STC ST10959SC, 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 14 CFR 21.101.

Novel or Unusual Design Features

The Hawker Beechcraft Model 400A will incorporate the following novel or unusual design features: A Mid-Continent TS835 Emergency Power Supply and MD302 Standby Attitude Module that use a rechargeable lithium batteries and battery systems. Rechargeable lithium batteries are a novel or unusual design feature in transport category airplanes for which the applicable airworthiness regulations do not contain adequate or appropriate safety standards. 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.

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 re-codification 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 that led to additional rulemaking affecting large transport category 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. At Amendment 25-123, effective December 10, 2007, the FAA issued a revised § 25.1353, which moved the battery requirements to § 25.1353(b)(1) through (b)(6).

The proposed use of rechargeable lithium batteries for equipment and systems on the Model 400A, modified by STC ST10959SC 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 rechargeable lithium batteries that could affect the safety of the airplane and its passengers and crew.

At present, commercial aviation has limited experience with use of rechargeable lithium 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 rechargeable lithium batteries. These problems include overcharging, over-discharging, and flammability of cell components.

1. Overcharging

In general, lithium batteries 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 lithium battery cells 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 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 container.

These problems experienced by users of lithium batteries 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 battery installations in the Hawker Beechcraft 400A and to ensure, as required by §§ 25.1309 and 25.601, that these batteries are not hazardous or unreliable.

Applicability

As discussed above, these special conditions are applicable to STC ST10959SC, which modifies the Hawker Beechcraft Model 400A airplane. Should Nextant Aerospace apply at a later date to amend this STC to incorporate the same novel or unusual design feature, the special conditions would apply to that STC as well.

Conclusion

This action affects only certain novel or unusual design features on one airplane model. 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 substance contained herein. Therefore, because a delay would significantly affect the certification date for the modification of the airplane, the FAA has determined that prior public notice and comment are unnecessary and impracticable, and good cause exists for adopting these special conditions upon publication in the Federal Register. The FAA is requesting comments to allow interested persons to submit views that may not have been submitted in response to the prior opportunities for comment described above.

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 type certification basis for Hawker Beechcraft Model 400A airplanes modified by Nextant Aerospace.

Installed Rechargeable Lithium Batteries and Battery Systems

These special conditions require that (1) All characteristics of the rechargeable lithium batteries and battery installation, that could affect safe operation of the Hawker Beechcraft 400A 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 Title 14, Code of Federal Regulations (14 CFR) 25.1353(b)(1) through (b)(4) at Amendment 25-123, all rechargeable lithium batteries and battery installations on Hawker Beechcraft 400A airplanes modified by ST10959SC 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 battery installation must preclude explosion in the event of those failures.

2. Design of the rechargeable lithium batteries and battery systems must preclude the occurrence of self-sustaining, uncontrolled increases in temperature or pressure.

3. No explosive or toxic gases 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.

4. Installations of rechargeable lithium batteries must meet the requirements of § 25.863(a) through (d).

5. No corrosive fluids or gases that may escape from any rechargeable lithium battery 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 rechargeable lithium battery installation 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 battery installations must have a system to control the charging rate of the battery automatically, so as to prevent battery overheating or overcharging, and,

a. 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,

b. 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 battery installation, the function of which 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 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 battery is sufficiently charged at appropriate intervals specified by the battery manufacturer and the equipment manufacturer that contain the rechargeable lithium battery or rechargeable lithium battery system. This is required to ensure that lithium rechargeable batteries and lithium rechargeable battery systems will not degrade below specified ampere-hour levels sufficient to power the airplane systems 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 battery and rechargeable lithium battery systems, which could result in short-circuit or other unintentional impact damage caused by dropping or other destructive means that could result in personal injury or property damage.

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 25-123 in the certification basis of airplane Hawker Beechcraft 400A airplanes. These special conditions apply only to rechargeable lithium batteries and lithium battery systems and their installations. The requirements of § 25.1353(b) at Amendment 25-123 remain in effect for batteries and battery installations on Hawker Beechcraft 400A airplanes that do not use lithium batteries.

Issued in Renton, Washington, on September 9, 2014.

Jeffrey E. Duven,

Manager, Transport Airplane Directorate, Aircraft Certification Service.