Special Conditions: Delta Flight Products, Non-Rechargeable Lithium Batteries and Battery System Installations

<RULE> DEPARTMENT OF TRANSPORTATION <SUBAGY>Federal Aviation Administration</SUBAGY> <CFR>14 CFR Part 25</CFR> <DEPDOC>[Docket No. FAA-2025-0968; Special Conditions No. 25-879-SC]</DEPDOC> <SUBJECT>Special Conditions: Delta Flight Products, Non-Rechargeable Lithium Batteries and Battery System Installations</SUBJECT> <HD SOURCE="HED">AGENCY:</HD> Federal Aviation Administration (FAA), DOT. <HD SOURCE="HED">ACTION:</HD> Final special conditions; request for comments. <SUM> <HD SOURCE="HED">SUMMARY:</HD> These special conditions are issued for a supplemental type certificate (STC) to install non-rechargeable lithium batteries and battery systems on certain transport-category airplanes. These airplanes, as modified by Delta Flight Products, 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 non-rechargeable lithium batteries and battery system installed in emergency locator transmitters (ELTs). 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. </SUM> <EFFDATE> <HD SOURCE="HED">DATES:</HD> This action is effective on Delta Flight Products on June 4, 2025. Send comments on or before July 21, 2025. </EFFDATE> <HD SOURCE="HED">ADDRESSES:</HD> Send comments identified by Docket No. FAA-2025-0968 using any of the following methods: • <E T="03">Federal eRegulations Portal:</E> Go to <E T="03">www.regulations.gov</E> and follow the online instructions for sending your comments electronically. • <E T="03">Mail:</E> 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. • <E T="03">Hand Delivery or Courier:</E> 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. • <E T="03">Fax:</E> Fax comments to Docket Operations at 202-493-2251. • <E T="03">Docket:</E> Background documents or comments received may be read at <E T="03">www.regulations.gov</E> at any time. Follow the online instructions for accessing the docket or go 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. <FURINF> <HD SOURCE="HED">FOR FURTHER INFORMATION CONTACT:</HD> Nazih Khaouly, Electrical Systems, AIR-626A, Technical Policy Branch, Policy and Standards Division, Aircraft Certification Service, Federal Aviation Administration, 2200 S 216th Street, Des Moines, Washington 98198; telephone and fax 206-231-3160; email <E T="03">Nazih.Khaouly@faa.gov.</E> </FURINF> <SUPLINF> <HD SOURCE="HED">SUPPLEMENTARY INFORMATION:</HD> The substance of these special conditions has been published in the <E T="04">Federal Register</E> for public comment in several prior instances with no substantive comments received. Therefore, the FAA finds, pursuant to 14 CFR 11.38(b), that new comments are unlikely, and notice and comment prior to this publication are unnecessary. <HD SOURCE="HD1">Privacy</HD> Except for Confidential Business Information (CBI) as described in the following paragraph, and other information as described in title 14, Code of Federal Regulations (14 CFR) 11.35, the FAA will post all comments received without change to <E T="03">www.regulations.gov,</E> including any personal information you provide. The FAA will also post a report summarizing each substantive verbal contact received about these special conditions. <HD SOURCE="HD1">Confidential Business Information</HD> Confidential Business Information (CBI) is commercial or financial information that is both customarily and actually treated as private by its owner. Under the Freedom of Information Act (FOIA) (5 U.S.C. 552), CBI is exempt from public disclosure. If your comments responsive to these special conditions contain commercial or financial information that is customarily treated as private, that you actually treat as private, and that is relevant or responsive to these special conditions, it is important that you clearly designate the submitted comments as CBI. Please mark each page of your submission containing CBI as “PROPIN.” The FAA will treat such marked submissions as confidential under the FOIA, and the indicated comments will not be placed in the public docket of these special conditions. Send submissions containing CBI to the individual listed in the <E T="02">FOR FURTHER INFORMATION CONTACT</E> section above. Comments the FAA receives, which are not specifically designated as CBI, will be placed in the public docket for these proposed special conditions. <HD SOURCE="HD1">Comments Invited</HD> The FAA invites 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. The FAA will consider all comments received by the closing date for comments. The FAA may change these special conditions based on the comments received. <HD SOURCE="HD1">Background</HD> On December 19, 2024, Delta Flight Products applied for a supplemental type certificate ST12026AT to install non-rechargeable lithium batteries and battery systems in ELTs. Delta Flight Products intends to apply this STC to multiple transport-category airplanes, and may periodically amend this STC to expand its applicability to include additional transport-category airplane makes and models. <HD SOURCE="HD1">Type Certification Basis</HD> Under the provisions of title 14, Code of Federal Regulations (14 CFR) 21.101, Delta Flight Products must show that the airplanes, for which they make application to modify by FAA STC ST12026AT, as changed, continue to meet the applicable provisions of the regulations listed in each airplane's respective type certificate 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 T="03">i.e.,</E> 14 CFR part 25) do not contain adequate or appropriate safety standards 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 that incorporates 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 airplanes modified by STC ST12026AT 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. <HD SOURCE="HD1">Novel or Unusual Design Features</HD> The airplanes listed in the FAA STC ST12026AT approved model list (AML) will incorporate the following novel or unusual design feature: Non-rechargeable lithium batteries and battery systems installed in ELTs. <HD SOURCE="HD1">Discussion</HD> The FAA derived the current regulations governing installation of batteries in transport-category airplanes from Civil Air Regulations (CAR) 4b.625(d), as part of the recodification of CAR 4b, which established 14 CFR part 25 in February 1965. This recodification essentially reworded the CAR 4b battery requirements, which are currently in § 25.1353(b)(1) through (4). Non-rechargeable lithium batteries and battery systems are novel and unusual with respect to the state of technology considered when these requirements were codified. Non-rechargeable lithium batteries and battery systems introduce higher energy levels into airplane systems through new chemical compositions in various battery-cell sizes and constructions. Interconnection of these cells in battery packs introduces failure modes that require unique design considerations, such as provisions for thermal management. In January 2013, two independent events involving rechargeable lithium-ion batteries revealed unanticipated failure modes. A National Transportation Safety Board Safety Recommendation to the FAA, dated May 22, 2014, which is available at <E T="03">www.ntsb.gov,</E> filename <E T="03">A-14-032-036.pdf,</E> describes these events. On July 12, 2013, an event involving a non-rechargeable lithium battery in an ELT installation demonstrated unanticipated failure modes. The United Kingdom's Air Accidents Investigation Branch Bulletin S5/2013  <SU>1</SU> <FTREF/> describes this event. These events, involving rechargeable and non-rechargeable lithium batteries, prompted the FAA to reevaluate these energy-storage technologies. <FTNT> <SU>1</SU>   <E T="03">See</E> Aircraft Aircraft Accident Report 2/2015—Boeing B787-8, ET-AOP, 12 July 2013 Ground fire at London Heathrow Airport on 12 July 2013. <E T="03">www.gov.uk/aaib-reports/aircraft-accident-report-2-2015-boeing-b787-8-et-aop-12-july-2013</E> . </FTNT> On April 22, 2016, the FAA published special conditions no. 25-612- ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Preview showing 10k of 18k characters. Full document text is stored and available for version comparison. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━