Special Conditions: CFM International, LEAP-1B Engine Model; Incorporation of Woven Composite Fan Blades

<RULE> DEPARTMENT OF TRANSPORTATION <SUBAGY>Federal Aviation Administration</SUBAGY> <CFR>14 CFR Part 33</CFR> <DEPDOC>[Docket No. FAA-2015-4220; Special Conditions No. 33-017-SC]</DEPDOC> <SUBJECT>Special Conditions: CFM International, LEAP-1B Engine Model; Incorporation of Woven Composite Fan Blades</SUBJECT> <HD SOURCE="HED">AGENCY:</HD> Federal Aviation Administration (FAA), DOT. <HD SOURCE="HED">ACTION:</HD> Final special conditions; request for comments; amendment. <SUM> <HD SOURCE="HED">SUMMARY:</HD> This action amends Special Condition No. 33-017-SC for the CFM International (CFM) Model LEAP-1B engines. These engines have a novel or unusual design feature associated with the engine fan blades—incorporation of woven composite fan blades. The applicable airworthiness regulations do not contain adequate or appropriate safety standards for this design feature. These special conditions, as amended, 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 CFM International on August 4, 2025. Send comments on or before September 18, 2025. </EFFDATE> <HD SOURCE="HED">ADDRESSES:</HD> Send comments identified by Docket No. FAA-2015-4220 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> Philip Haberlen, Engine and Propulsion Section, AIR-625, Technical Policy Branch, Policy and Standards Division, Federal Aviation Administration, FAA AIR Office, 1200 District Ave, Burlington, MA 01803; telephone (781) 238-7770; email <E T="03">Philip.haberlen@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 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 June 27, 2012, CFM International (CFM) applied for a new type certificate (TC) to include the LEAP-1A and -1C engine models. Additionally, on May 9, 2013, CFM applied for a new TC to include the LEAP-1B engine models. The LEAP engine models are high-bypass-ratio engines that incorporate a novel and unusual design feature—new woven composite fan blades. The woven composite fan blades will have significant differences in material property characteristics when compared to conventionally designed fan blades using non-composite metallic materials. The FAA issued Special Condition No. 33-017-SC for the LEAP-1B engines with this design feature on October 30, 2015. Special Condition No. 33-017-SC became effective on December 21, 2015 (80 FR 72561, November 20, 2015). The FAA issued TC E00088EN on May 4, 2016. Subsequently, CFM highlighted an error in these Special Condition and submitted a type design change request on July 18, 2024. The FAA is proposing changes to Special Conditions No. 33-017-SC based on CFM's application. <HD SOURCE="HD1">Type Certification Basis</HD> Under the provisions of Title 14, Code of Federal Regulations (14 CFR) 21.17, CFM must show that the Model LEAP-1B engines meet the applicable provisions of the applicable regulations in effect on the date of application, except as detailed in paragraphs 21.101(b) and (c). The FAA has determined the following certification basis for the LEAP-1B engine models: Title 14 CFR part 33, “Airworthiness Standards: Aircraft Engines,” dated February 1, 1965, with Amendments 33-1 through 33-33, dated September 20, 2012. If the Administrator finds that the applicable airworthiness regulations do not contain adequate or appropriate safety standards for the LEAP-1B engine models 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 TC for that model be amended later to include any other model that incorporates the same novel or unusual design feature, the special conditions would also apply to the other model under § 21.101. In addition to complying with the applicable airworthiness regulations and special conditions, the CFM LEAP-1B engine models must also comply with the fuel venting and exhaust emission requirements of 14 CFR part 34. 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 § 21.17(a)(2). <HD SOURCE="HD1">Novel or Unusual Design Features</HD> The LEAP-1B engine models will incorporate the following novel or unusual design feature: The LEAP-1B engine models will incorporate woven composite fan blades. The woven composite fan blades will have significant differences in material property characteristics when compared to conventionally designed fan blades using non-composite metallic materials. Composite material design provides the capability to incorporate multiple load paths and crack arresting features that prevent delamination or crack propagation to blade failure during the life of the blade. <HD SOURCE="HD1">Discussion</HD> The woven composite fan blades are a novel and unusual design feature that require additional airworthiness standards for type certification of the LEAP-1B engine models. The current requirements of § 33.94 are based on single-load path metallic fan blade characteristics and service history and are not appropriate for the unusual design features of the woven composite fan blade found on the CFM LEAP series turbofan engines. The properties of a composite blade are highly dependent of the composite ply configuration, matrix material, and manufacturing methods. The CFM LEAP engine incorporates 3-D woven resin transfer molding (RTM) technology in the design and manufacture of the blade. FAA requires that CFM conduct the required material testing per § 33.15 to determine material characteristics that include the effects of defects, manufacturing variations, contamination, environmental effect, and service damage on the material capability and blade life. Composite material design provides the capability to incorporate multiple load paths and crack arresting features that prevent delamination or crack propagation to blade failure during the life of the blade. The probability of failure that an appropriately designed composite fan blade will fail below the inner annulus flow path line may be highly improbable. The airworthiness regu ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Preview showing 10k of 19k characters. Full document text is stored and available for version comparison. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━