2019-08477. Special Conditions: Costruzioni Aeronautiche Tecnam S.P.A.; Model P2012 Airplane; Installation of Rechargeable Lithium Batteries

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Final special conditions; request for comments.

SUMMARY:

These special conditions are issued for the Costruzioni Aeronautiche Tecnam S.P.A., Model P2012 airplane. These airplanes will have a novel or unusual design feature associated with the installation of a rechargeable lithium battery. The applicable airworthiness regulations do not contain adequate or appropriate safety standards for this design feature. These special conditions contain the additional safety standards 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 April 26, 2019.

We must receive your comments by May 28, 2019.

ADDRESSES:

Send comments identified by docket number FAA-2019-0301 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 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://regulations.gov,, including any personal information the commenter provides. Using the search function of the docket website, 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).

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:

Ruth Hirt, Federal Aviation Administration, Aircraft Certification Service, Small Airplane Directorate, AIR-694, 901 Locust, Room 301, Kansas City, MO; telephone [phone]; facsimile (816)-329 4090.

SUPPLEMENTARY INFORMATION:

Reason for No Prior Notice and Comment Before Adoption

The FAA has determined, in accordance with 5 U.S. Code §§ 553(b)(3)(B) and 553(d)(3), that notice and opportunity for prior public comment are unnecessary because substantially identical special conditions have been subjected to the public comment process in several prior instances such that the FAA is satisfied that new comments are unlikely. For the same reason, the FAA finds that good cause exists for making these special conditions effective upon issuance. 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.

Special conditions No.	Company/airplane model
23-15-01-SC 1	Kestrel Aircraft Company/Model K-350.
23-16-02-SC 2	Pilatus Aircraft, Ltd, Models PC12, PC-12/45, and PC-12/47.
23-288-SC 3	St. Louis Helicopter, LLC, Textron Aviation Models B300, B300C, B300C(MC-12W), and B300C (UC-12W).
1 http://rgl.faa.gov/​Regulatory_​and_​Guidance_​Library/​rgSC.nsf/​0/​39B156C006EB842E86257EF3004BB13C?​OpenDocument&​Highlight=​installation%20of%20rechargeable%20lithium%20battery.
2 http://rgl.faa.gov/​Regulatory_​and_​Guidance_​Library/​rgSC.nsf/​0/​5A2FEC165CB4913086258019005C34E2?​OpenDocument&​Highlight=​23-278-sc.
3 http://rgl.faa.gov/​Regulatory_​and_​Guidance_​Library/​rgSC.nsf/​0/​B2D62B06A314D74186258282005F5E04?​OpenDocument&​Highlight=​23-288-sc.

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 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.

Background

On March 13, 2018, Costruzioni Aeronautiche Tecnam S.P.A. (Tecnam) applied for FAA validation of its type certificate for its new Model P2012 airplane. The airplane is a normal category, metallic, non-pressurized, high wing, monoplane that will seat nine passengers and two flightcrew. Two wing mounted Lycoming Model TEO-540-C1A piston engines driving four blade variable pitch constant speed MT-Propellers USA, Inc. Model MTV-14-B-C-F/CF195-30b propellers power the airplane. The airplane has fixed tricycle landing gear, a Garmin G1000 NXi avionics suite, and a maximum takeoff weight of 7,937 pounds. The Model P2012 has rechargeable lithium batteries installed for higher energy density instead of the nickel-cadmium (Ni-Cd) or lead-acid rechargeable batteries.

The current regulatory requirements for part 23 airplanes do not contain adequate requirements for use of rechargeable lithium batteries in airborne applications. This type of battery possesses certain failure and operational characteristics with maintenance requirements that differ significantly from that of the nickel-cadmium (Ni-Cd) and lead-acid rechargeable batteries approved in § 23.1553, amendment 23-62 or earlier, for other normal, utility, acrobatic, and commuter category airplanes. Therefore, the FAA is issuing this special condition to address—

• All characteristics of the rechargeable lithium batteries and their installation that could affect safe operation of the Model P2012 airplane; and
• Appropriate Instructions for Continued Airworthiness (ICA) that include maintenance requirements to ensure the availability of electrical power from the batteries when needed.

Type Certification Basis

Under the provisions of § 21.17, Tecnam must show that the Model P2012 airplane meets the applicable provisions of part 23, as amended by amendment 23-1 through 23-62 thereto.

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 P2012 airplane because of a novel or unusual design feature, special conditions are prescribed under the provisions of § 21.16.

In addition to the applicable airworthiness regulations and special conditions, the Model P2012 airplane 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 § 611 of Public Law 92-574, the “Noise Control Act of 1972.”

The FAA issues special conditions, as defined in § 11.19, under § 11.38 and they become part of the type certification basis under § 21.17(a)(2).

Special conditions are initially applicable to the models for which they are issued. Should the type certificate for that model be amended later to include any other model that incorporates the same novel or unusual design feature, the FAA would apply these special conditions to the other model.

Novel or Unusual Design Features

The Model P2012 airplane will incorporate the following novel or unusual design features: The installation of a rechargeable lithium battery—intended as energy storage for the airplane—will power the essential load for continued safe flight and landing if the electrical generating system fails.

Discussion

The applicable regulations governing the installation of batteries in general aviation airplanes were derived from Civil Air Regulations (CAR) 3 as part of the recodification that established 14 CFR part 23. The battery requirements identified in § 23.1353 were a rewording of the CAR requirements. Subsequent rulemaking activities—resulting from increased incidents of Ni-Cd battery fire or failures—added § 23.1353(f) and (g), amendments 23-20 and 23-21, respectively. The FAA did not envision the introduction of lithium battery installations when these regulations were published.

The proposed use of rechargeable lithium batteries prompted the FAA to review the adequacy of these existing regulations. We determined the existing regulations do not adequately address the safety of lithium battery installations.

Current experience with rechargeable lithium batteries in commercial or general aviation is limited. However, other users of this technology—ranging from personal computers, to wireless telephone manufacturers, to the electric vehicle industry—have noted safety problems with rechargeable lithium batteries. These problems, as described in the following paragraphs, include overcharging, over-discharging, flammability of cell components, cell internal defects, and hazards resulting from exposure to extreme temperatures.

1. Overcharging. In general, rechargeable lithium batteries are significantly more susceptible than their Ni-Cd or lead-acid counterparts to thermal runaway, which is an internal failure that can result in self-sustaining increases in temperature and pressure. This 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 rechargeable lithium battery cells beyond the manufacturer's recommended specification 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 flight crews as a means of checking battery status—a problem shared with Ni-Cd batteries. In addition, over-discharging has the potential to lead to an unsafe condition (creation of dendrites that could result in internal short circuit during the recharging cycle).

3. Flammability of Cell Components. Unlike Ni-Cd and lead-acid batteries, some types of rechargeable 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.

4. Cell Internal Defects. The rechargeable lithium batteries and rechargeable battery systems have a history of undetected cell internal defects. These defects may or may not be detected during normal operational evaluation, test, and validation. This may lead to an unsafe condition during in-service operation.

5. Extreme Temperatures. Exposure to an extreme temperature environment has the potential to create major hazards. Care must be taken to ensure that the lithium battery remains within the manufacturer's recommended specification.

Applicability

As discussed above, these special conditions are applicable to the Model P2012 airplane. Should Tecnam 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 FAA would apply these special conditions to that model as well.

Conclusion

This action affects only certain novel or unusual design features on the Model P2012 airplane. It is not a rule of general applicability.

List of Subjects in 14 CFR Part 23

• Aircraft
• Aviation safety
• Signs and symbols

Citation

The authority citation for these special conditions is as follows:

Authority: 49 U.S.C. 106(f), 106(g), 40113, 44701-44702, 44704, Pub. L. 113-53, 127 Stat 584 (49 U.S.C. 44704) note

The Special Conditions

Accordingly, pursuant to the authority delegated to me by the Administrator, the following special conditions are issued, in lieu of the requirements in § 23.1353 (a), (b), (c), (d), and (e), amendment 23-62, as part of the type certification basis for the Tecnam Model P2012 airplane.

Installation of Lithium Battery

Lithium battery installations must be designed and installed as follows:

(1) Safe cell temperatures and pressures must be maintained during—

i. Normal operations;

ii. Any probable failure conditions of charging or discharging or battery monitoring system; and

iii. Any failure of the charging or battery monitoring system shown to not be extremely remote.

(2) The rechargeable lithium battery installation must be designed to preclude explosion and fire in the event of a failure under (1)(ii) and (1)(iii) above.

(3) Design of the rechargeable lithium batteries must preclude the occurrence of self-sustaining, uncontrolled increases in temperature or pressure.

(4) No explosive or toxic gasses 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 shown to not be extremely remote, may accumulate in hazardous quantities within the airplane.

(5) Installations of rechargeable lithium batteries must meet the requirements of § 23.863(a) through (d), amendment 23-34.

(6) No corrosive fluids or gases that may escape from any rechargeable lithium battery may damage surrounding structure or any adjacent systems, equipment, electrical wiring, or the airplane in such a way as to cause a major or more severe failure condition, in accordance with § 23.1309, amendment 23-62.

(7) Each rechargeable lithium 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.

(8) Rechargeable lithium battery installations must have a system to automatically control the charging rate of the battery to prevent battery overheating and overcharging, and either:

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.

(9) Any rechargeable lithium battery installation, the function of which is required for safe operation of the aircraft, 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 aircraft.

Note 1 to paragraph (9):

Reference § 23.1353(h) for dispatch consideration.

(10) The Instructions for Continued Airworthiness (ICA) required by § 23.1529 must contain maintenance requirements to ensure that the battery has been 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. The lithium rechargeable batteries and lithium rechargeable battery systems must not degrade below specified ampere-hour levels sufficient to power the aircraft system. The ICA must also contain procedures for the maintenance of replacement batteries to prevent the installation of batteries that have 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.

Note 2 to paragraph (10):

Maintenance requirements include procedures that check battery capacity, charge degradation at manufacturer's recommended inspection intervals, and replace batteries at manufacturer's recommended replacement schedule/time to prevent age-related degradation.

Note 3 to paragraph (10):

The term “sufficiently charged” means that the battery must retain enough charge, expressed in ampere-hours, to ensure that the battery cells will not be damaged. A battery cell may be damaged by low charge (i.e., below certain level), resulting in 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 4 to paragraph (10):

Replacement battery in spares storage may be subject to prolonged storage at a low state of charge.

Issued in Kansas City, Missouri, on April 22, 2019.

William Schinstock,

Acting Manager, Small Airplane Standards Branch, Policy and Innovation Division, Aircraft Certification Service.