Airworthiness Directives; MHI RJ Aviation ULC (Type Certificate Previously Held by Bombardier, Inc.) Airplanes

<RULE> DEPARTMENT OF TRANSPORTATION <SUBAGY>Federal Aviation Administration</SUBAGY> <CFR>14 CFR Part 39</CFR> <DEPDOC>[Docket No. FAA-2025-3995; Project Identifier MCAI-2025-01653-T; Amendment 39-23180; AD 2025-22-02]</DEPDOC> <RIN>RIN 2120-AA64</RIN> <SUBJECT>Airworthiness Directives; MHI RJ Aviation ULC (Type Certificate Previously Held by Bombardier, Inc.) Airplanes</SUBJECT> <HD SOURCE="HED">AGENCY:</HD> Federal Aviation Administration (FAA), DOT. <HD SOURCE="HED">ACTION:</HD> Final rule; request for comments. <SUM> <HD SOURCE="HED">SUMMARY:</HD> The FAA is adopting a new airworthiness directive (AD) for certain MHI RJ Aviation ULC (type certificate previously held by Bombardier, Inc.) Model CL-600-2C10 (Regional Jet Series 700, 701 & 702), CL-600-2C11 (Regional Jet Series 550), CL-600-2D15 (Regional Jet Series 705), CL-600-2D24 (Regional Jet Series 900), and CL-600-2E25 (Regional Jet Series 1000) airplanes. This AD was prompted by reports of loose and missing bolts on the horizontal stabilizer (H-stab) anti-yaw steady fitting block. This AD requires repetitive torque checks of the H-stab anti-yaw steady fitting block bolts. The FAA is issuing this AD to address the unsafe condition on these products. </SUM> <EFFDATE> <HD SOURCE="HED">DATES:</HD> This AD is effective November 20, 2025. The FAA must receive comments on this AD by December 22, 2025. </EFFDATE> <HD SOURCE="HED">ADDRESSES:</HD> You may send comments, using the procedures found in 14 CFR 11.43 and 11.45, by any of the following methods: • <E T="03">Federal eRulemaking Portal:</E> Go to <E T="03">regulations.gov</E> . Follow the instructions for submitting comments. • <E T="03">Fax:</E> 202-493-2251. • <E T="03">Mail:</E> U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue SE, Washington, DC 20590. • <E T="03">Hand Delivery:</E> Deliver to Mail address above between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. <E T="03">AD Docket:</E> You may examine the AD docket at <E T="03">regulations.gov</E> under Docket No. FAA-2025-3995; or in person at Docket Operations between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains this final rule, the mandatory continuing airworthiness information (MCAI), any comments received, and other information. The street address for Docket Operations is listed above. <E T="03">Material Incorporated by Reference:</E> • For Transport Canada material identified in this AD, contact Transport Canada, Transport Canada National Aircraft Certification, 159 Cleopatra Drive, Nepean, Ontario K1A 0N5, Canada; telephone 888-663-3639; email <E T="03">TC.AirworthinessDirectives-Consignesdenavigabilite.TC@tc.gc.ca</E> . You may find this material on the Transport Canada website at <E T="03">tc.canada.ca/en/aviation</E> . • You may view this material at the FAA, Airworthiness Products Section, Operational Safety Branch, 2200 South 216th St., Des Moines, WA. For information on the availability of this material at the FAA, call 206-231-3195. It is also available at <E T="03">regulations.gov</E> under Docket No. FAA-2025-3995. <FURINF> <HD SOURCE="HED">FOR FURTHER INFORMATION CONTACT:</HD> Fatin Saumik, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; phone: 516-228-7300; email: <E T="03">9-avs-nyaco-cos@faa.gov</E> . </FURINF> <SUPLINF> <HD SOURCE="HED">SUPPLEMENTARY INFORMATION:</HD> <HD SOURCE="HD1">Comments Invited</HD> The FAA invites you to send any written data, views, or arguments about this final rule. Send your comments using a method listed under the <E T="02">ADDRESSES</E> section. Include “Docket No. FAA-2025-3995; Project Identifier MCAI-2025-01653-T” at the beginning of your comments. The most helpful comments reference a specific portion of the final rule, explain the reason for any recommended change, and include supporting data. The FAA will consider all comments received by the closing date and may amend this final rule because of those comments. Except for Confidential Business Information (CBI) as described in the following paragraph, and other information as described in 14 CFR 11.35, the FAA will post all comments received, without change, to <E T="03">regulations.gov,</E> including any personal information you provide. The agency will also post a report summarizing each substantive verbal contact received about this final rule. <HD SOURCE="HD1">Confidential Business Information</HD> 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 this AD contain commercial or financial information that is customarily treated as private, that you actually treat as private, and that is relevant or responsive to this AD, 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 they will not be placed in the public docket of this AD. Submissions containing CBI should be sent to Fatin Saumik, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; phone: 516-228-7300; email: <E T="03">9-avs-nyaco-cos@faa.gov</E> . Any commentary that the FAA receives which is not specifically designated as CBI will be placed in the public docket for this rulemaking. <HD SOURCE="HD1">Background</HD> Transport Canada, which is the aviation authority for Canada, has issued Transport Canada AD CF-2025-38, effective August 19, 2025 (Transport Canada AD CF-2025-38) (also referred to as the MCAI), to correct an unsafe condition for certain MHI RJ Aviation ULC Model CL-600-2C10 (Regional Jet Series 700, 701, and 702), CL-600-2C11 (Regional Jet Series 550), CL-600-2D15 (Regional Jet Series 705), CL-600-2D24 (Regional Jet Series 900), and CL-600-2E25 (Regional Jet Series 1000) airplanes. The MCAI states that during the completion of a maintenance task on the horizontal stabilizer, a bolt from the horizontal stabilizer anti-yaw steady fitting block was missing. The missing bolt and associated hardware were found lying on adjacent structure. Other bolts in the same bolt group on the anti-yaw steady fitting block were found to be loose. The anti-yaw steady fitting block bolts do not have a secondary locking feature. Loose or missing bolts on the anti-yaw steady fitting block when combined with a bird strike or gust loading may result in loss of the horizontal stabilizer. The FAA is issuing this AD to address loose or missing bolts on the anti-yaw steady fitting block, which, when combined with a bird strike or gust loading, may result in loss of the horizontal stabilizer and consequent loss of control of the airplane. You may examine the MCAI in the AD docket at <E T="03">regulations.gov</E> under Docket No. FAA-2025-3995. <HD SOURCE="HD1">Material Incorporated by Reference Under 1 CFR Part 51</HD> The FAA reviewed Transport Canada AD CF-2025-38, which specifies procedures for repetitive torque checks of the H-stab anti-yaw steady fitting block bolts. The torque check consists of inspecting the tightening torque on the four attachment bolts that attach the steady block by replacing any bolt or nut that is loose or missing and then torquing all four bolts and nuts. Transport Canada AD CF-2025-38 also specifies procedures to replace the H-Stab anti-yaw steady fitting block hardware. The replacement includes measuring four-hole diameters on the steady block and steady fitting; rework (ream) any hole diameter if required; and installing and torquing new hardware attachments (bolts, nuts, washers, and cotter pins) to create a double safety device on the hardware that attach the steady block to the steady fitting. This material is reasonably available because the interested parties have access to it through their normal course of business or by the means identified in the <E T="02">ADDRESSES</E> section. <HD SOURCE="HD1">FAA's Determination</HD> These products have been approved by the civil aviation authority of another country and are approved for operation in the United States. Pursuant to the FAA's bilateral agreement with this State of Design Authority, that authority has notified the FAA of the unsafe condition described in the MCAI referenced above. The FAA is issuing this AD after determining that the unsafe condition described previously is likely to exist or develop on other products of the same type design. <HD SOURCE="HD1">Requirements of This AD</HD> This AD requires accomplishing the actions specified in Transport Canada AD CF-2025-38 described previously, except for any differences identified as exceptions in the regulatory text of this AD. See “Differences Between This AD and the MCAI” for a discussion of the general differences included in this AD. <HD SOURCE="HD1">Differences Between This AD and the MCAI</HD> Paragraph C. of the MCAI specifies to replace the H-stab anti-yaw steady fitting block hardware. The FAA is considering requiring this replacement, which would terminate the repetitive torque checks required by this AD. However, the planned compliance time for the replacement would be long enough to allow for notice and opportunity for public comments on the merits of the replacement. This AD therefore seeks such comments, while allowing the replacement as an optional terminating action for the repetitive torque checks. <HD SOURCE="HD1">Explanation of Required Compliance Information</HD> In the FAA's ongoing efforts to improve the efficiency of the AD process, the FAA developed a process to use some civil aviatio ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Preview showing 10k of 22k characters. Full document text is stored and available for version comparison. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━