Background The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by adding an AD that would apply to all Bombardier, Inc., Model CL-600-1A11 (600) and CL-600-2A12 (601) airplanes, and certain Model CL-600-2B16 (601-3A, 601-3R, and 604 Variants) airplanes. The NPRM was published in the Federal Register on April 11, 2025 (90 FR 15419). The NPRM was prompted by AD CF-2024-16, dated May 23, 2024 (also referred to as the MCAI), issued by Transport Canada, which is the aviation authority for Canada. The MCAI states that new or more restrictive airworthiness limitations have been developed. In the NPRM, the FAA proposed to require revising the existing maintenance or inspection program, as applicable, to incorporate new or more restrictive airworthiness limitations. The FAA is issuing this AD to address new or more restrictive limitations. Failure to comply with these new or more restrictive limitations could adversely affect the continued airworthiness of the airplane. You may examine the MCAI in the AD docket at regulations.gov under Docket No. FAA-2025-0616. Discussion of Final Airworthiness Directive Comments The FAA received comments from Bombardier. The following presents the comments received on the NPRM and the FAA's response to each comment. Request for Changing Reference to Website Bombardier requested updating the reference to its website because the customer portal link can be hard to find on some Support and Customer Services pages. To make access easier, Bombardier recommended providing a direct secure link to the portal. Furthermore, Bombardier stated that prefixing the website reference with " https:// " ensures a secure connection to the Bombardier customer portal, enhancing security and helping prevent man-in-the-middle attacks in certain regions. The FAA agrees with updating the reference to the Bombardier website. The FAA has changed " bombardier.com " to read " https://my.bombardier.com/" to ensure a secure connection to the Bombardier customer portal and that the website is up-to-date and clearly presented. Request To Revise "New and More Restrictive" Statement Bombardier requested that the phrase "new and more restrictive limitations" be revised to "new or more restrictive limitations" throughout the final rule. Bombardier explained that the phrase "new and more restrictive" could be misinterpreted as applying only to limitations that are both new and more restrictive, potentially excluding newly introduced airworthiness limitation (AWL) tasks that are not necessarily more restrictive. Bombardier asserted that using "new or more restrictive" is more accurate, all-encompassing, and less likely to cause confusion. The FAA agrees with the requested use of the term "new or more restrictive limitations" throughout the final rule. This terminology is consistent with the standard language used in current ADs. The FAA has revised this AD accordingly. Request for Changing the Description of the Limitations Bombardier requested that the sentence in the third paragraph under the "Background" Section of the proposed AD that specifies "The new and more restrictive limitations include tasks and limitations . . ." be revised to include the phrase: "new limitation tasks, as well as existing limitation tasks for which additional effectivity was added, a threshold or repeat interval was reduced, a discard time was reduced, or an inspection method was changed." The FAA acknowledges that Bombardier is identifying additional changes within the airworthiness limitation tasks. However, the FAA disagrees with revising this final rule as suggested by Bombardier because that level of detail of how specific airworthiness limitation tasks have changed is not necessary. The FAA considers the existing language in this AD to be sufficient to describe the applicable time limits/maintenance checks (TLMC) documents and, therefore, has not changed this AD in this regard. Request for Removal of Sections That Do Not Apply Bombardier requested the removal of Sections 5-20-00, 5-30-20, and 5-70-00 from the proposed AD, as Transport Canada AD CF-2024-16, dated May 23, 2024, references the AWL within the TLMC documents. The FAA agrees to remove Sections 5-20-00, 5-30-20, and 5-70-00 after confirming with Transport Canada that the intent of the MCAI applies only to Section 5-10-00, "Airworthiness Limitations." Therefore, the FAA has removed reference to Sections 5-20-00, 5-30-20, and 5-70-00 from this AD. Request To Mandate Additional TLMCs and Temporary Revisions Bombardier requested that the FAA mandate all new or more restrictive limitations included in the latest published TLMC revisions. Bombardier noted that numerous Temporary Revisions (TRs) have been issued, containing updated or more restrictive limitations that should be incorporated into operators' aircraft maintenance programs. Bombardier explained that if the FAA decides not to mandate the latest TLMC revisions and associated TRs, a subparagraph should be added to the proposed AD to provide credit to operators who voluntarily incorporate these revisions, or any subsequently approved TLMC revisions, into their maintenance programs. The FAA disagrees with mandating all new or more restrictive limitations included in the latest published TLMC revisions and the associated TRs issued thereafter. The FAA notes that Transport Canada has not issued an AD requiring these later TLMC revisions and TRs. In addition, to require more restrictive limitations than those identified in the proposed AD would necessitate (under the provisions of the Administrative Procedure Act) reissuing the notice, reopening the period for public comment, considering additional comments subsequently received, and eventually issuing a final rule. In light of this, the FAA has determined that further delay of this AD is not appropriate. The FAA has determined that an unsafe condition exists and that incorporating the limitations specified in this AD must be done to ensure continued safety. The FAA might consider additional rulemaking in the future to mandate new or more restrictive limitations. Therefore, the FAA has not revised this AD in this regard. Request To Exclude Service Information From Website Bombardier requested exclusion of the required service information that is incorporated by reference from public posting on the regulations.gov online docket and identified that service information as Confidential Business Information (CBI). Bombardier asserted that a paper copy may be incorporated by reference in the Library of Congress version. Bombardier explained that the listed service information is reasonably available through the normal distribution channels or as identified in the ADDRESSES section. Bombardier added that interested parties can register on the Bombardier customer portal ( https://my.bombardier.com/ ) to obtain access to the referenced service information. The FAA disagrees with excluding service information that is incorporated by reference from public posting on the regulations.gov online docket. The FAA clarifies that the CBI section of the NPRM applies only to information submitted by a commenter as part of their comment, and not to documents required for compliance. The FAA notes that any material incorporated by reference is also available at the National Archives and Records Administration's (NARA) Washington, DC, area offices, in addition to being accessible via regulations.gov. The FAA has not changed this AD in this regard. Conclusion 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 reviewed the relevant data, considered any comments received, and determined that air safety requires adopting this AD as proposed. Accordingly, the FAA is issuing this AD to address the unsafe condition on these products. Except for minor editorial changes, and any other changes described previously, this AD is adopted as proposed in the NPRM. None of the changes will increase the economic burden on any operator. Material Incorporated by Reference Under 1 CFR Part 51 The FAA reviewed the following Bombardier material: - Section 5-10-00, "Airworthiness Limitations," of Bombardier Challenger 600 Time Limits/Maintenance Checks (TLMC), Publication No. PSP 605, Revision 39, dated January 8, 2018. (For obtaining these sections of Bombardier Challenger 600 TLMC, Publication No. PSP 605, use Document Identification No. CH 600 TLMC.) - Section 5-10-00, "Airworthiness Limitations," of Bombardier Challenger 601 TLMC, Publication No. PSP 601-5, Revision 46, dated January 8, 2018. (For obtaining these sections of Bombardier Challenger 601 TLMC, Publication No. PSP 601-5, use Document Identification No. CH 601 TLMC.) - Section 5-10-00, "Airworthiness Limitations," of Bombardier Challenger 601 TLMC, Publication No. PSP 601A-5, Revision 42, dated January 8, 2018. (For obtaining these sections of Bombardier Challenger 601 TLMC, Publication No. PSP 601A-5, use Document Identification No. CH 601 TLMC-1.) - Part 2, "Airworthiness Limitations," of Bombardier Challenger 604 TLMC, Publication No. CH 604 TLMC, Revision 33, dated November 22, 2022. (The document identification number for ordering Bombardier Challenger 604 TLMC, Publication No. CH 604 TLMC is incorrectly identified as "CH 600 TLMC" on page 2 of the TLMC. For obtaining Part 2 of Bombardier Challenger 604 TLMC, Publication No. CH 604 TLMC, use Document Identification No. CH 604 TLMC.) - Part 2, "Airworthiness Limitations," of Bombardier Challenger 605 TLMC, Publication No. CH 605 TLMC, Revision 22, dated November 22, 2022. - Part 2, "Airworthiness Limitations," of Bombardier Challenger 650 TLMC, Publication No. CH 650 TLMC, Revision 9, dated November 22, 2022. This material specifies new or more restrictive airworthiness limitations, which includes certain certification maintenance requirements for airplane structures and safe life limits, among other limitations. These documents are distinct since they apply to different airplane configurations. The FAA also reviewed the following Bombardier material: - Temporary Revision No. 5-2-5, dated October 16, 2023, which includes new Task 32-51-04-101*, "Discard of the Nosewheel-Steering Control Potentiometer Coupling Setscrews, Part No. B0201102-2-220 (A/C 6194 and Subs or Post SB 650-32-007)." - Temporary Revision No. 5-2-29, dated October 25, 2023, which includes new Task 32-51-04-101*, "Discard of the Nosewheel-Steering Control Potentiometer Coupling Setscrews, Part No. B0201102-2-220 (Post SB 605-32-010)." - Temporary Revision No. 5-2-73, dated October 25, 2023, which includes new Task 32-51-04-101*, "Discard of the Nosewheel-Steering Control Potentiometer Coupling Setscrews, Part No. B0201102-2-220 (Post SB 604-32-033)." - Temporary Revision No. TR 5-164, dated December 23, 2022, which includes new Task 53-10-01-102*, "Forward Pressure Bulkhead Cap Angle-Aft Side." - Temporary Revision No. TR 5-165, dated October 25, 2023. - Temporary Revision No. TR 5-268, dated December 23, 2022, which includes new Task 53-10-01-103*, "Forward Pressure Bulkhead Cap Angle-Aft Side." - Temporary Revision No. TR 5-269, dated October 25, 2023. - Temporary Revision No. TR 5-282, dated December 23, 2022, which includes new Task 53-10-01-103*, "Forward Pressure Bulkhead Cap Angle-Aft Side." - Temporary Revision No. TR 5-283, dated October 25, 2023. (The asterisk (or "one star") with the last three digits of the task numbers listed above indicates that the task is an airworthiness limitation task.). Temporary Revision No. 5-2-5, 5-2-29, 5-2-73, TR 5-165, TR 5-269, and TR 5-283 introduce a life limit for potentiometer coupling setscrews, P/N B0201102-2-220, for the nosewheel- steering control or rudder pedal, as applicable. Temporary Revision Nos. TR 5-164, TR 5-268, and TR 5-282 introduce a visual check of the forward pressure bulkhead cap angle on the aft side. These documents are distinct since they apply to different airplane configurations. 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 ADDRESSES section. Costs of Compliance The FAA estimates that this AD affects 427 airplanes of U.S. registry. The FAA estimates the following costs to comply with this AD: The FAA has determined that revising the maintenance or inspection program takes an average of 90 work-hours per operator, although the agency recognizes that this number may vary from operator to operator. Since operators incorporate maintenance or inspection program changes for their affected fleet(s), the FAA has determined that a per-operator estimate is more accurate than a per-airplane estimate. Therefore, the agency estimates the average total cost per operator to be $7,650 (90 work-hours x $85 per work-hour). Authority for This Rulemaking Title 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, section 106, describes the authority of the FAA Administrator. Subtitle VII: Aviation Programs, describes in more detail the scope of the Agency's authority. The FAA is issuing this rulemaking under the authority described in Subtitle VII, Part A, Subpart III, Section 44701: General requirements. Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action. Regulatory Findings This AD will not have federalism implications under Executive Order 13132. This AD will not have a substantial direct effect on the States, on the relationship between the national government and the States, or on the distribution of power and responsibilities among the various levels of government. For the reasons discussed above, I certify that this AD: (1) Is not a "significant regulatory action" under Executive Order 12866, (2) Will not affect intrastate aviation in Alaska, and (3) Will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act. List of Subjects in 14 CFR Part 39 Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety. The Amendment Accordingly, under the authority delegated to me by the Administrator, the FAA amends 14 CFR part 39 as follows: PART 39-AIRWORTHINESS DIRECTIVES 1. The authority citation for part 39 continues to read as follows: Authority: 49 U.S.C. 106(g), 40113, 44701. § 39.13 [Amended] 2. The FAA amends § 39.13 by adding the following new airworthiness directive: 2025-17-12 Bombardier, Inc.: Amendment 39-23122; Docket No. FAA-2025-0616; Project Identifier MCAI-2024-00304-T. (a) Effective Date This airworthiness directive (AD) is effective October 31, 2025. (b) Affected ADs None. (c) Applicability This AD applies to the Bombardier, Inc., airplanes identified in paragraphs (c)(1) and (2) of this AD, certificated in any category. (1) All Model CL-600-1A11 (600), CL-600-2A12 (601), and CL-600-2B16 (601-3A and 601-3R Variants) airplanes. (2) Model CL-600-2B16 (604 Variant) airplanes, serial numbers 6050 through 6192 inclusive. (d) Subject Air Transport Association (ATA) of America Code 05, Time Limits/Maintenance Checks. (e) Unsafe Condition This AD was prompted by a determination that new or more restrictive airworthiness limitations are necessary. The FAA is issuing this AD to address new or more restrictive limitations. Failure to comply with these new or more restrictive limitations could adversely affect the continued airworthiness of the airplane. (f) Compliance Comply with this AD within the compliance times specified, unless already done. (g) Maintenance or Inspection Program Revision (1) Within 90 days after the effective date of this AD, revise the existing maintenance or inspection program, as applicable, to incorporate the information specified in the applicable time limits/maintenance checks (TLMC) document identified in table 1 to paragraph (g)(1) of this AD. The initial compliance time for doing the tasks is at the time specified in the applicable TLMC document identified in table 1 to paragraph (g)(1) of this AD, or within 90 days after the effective date of this AD, whichever occurs later, except as provided by paragraph (h) of this AD. BILLING CODE 4910-13-P ER26SE25.000 Table 1 to Paragraph (g)(1)-TLMC Documents ER26SE25.001 Table 2 to paragraph (g)(2)-Temporary Revisions ER26SE25.002 (2) Within 90 days after the effective date of this AD, revise the existing maintenance or inspection program, as applicable, to incorporate the information specified in the applicable temporary revisions (TRs) identified in table 2 to paragraph (g)(2) of this AD. The initial compliance time for doing the tasks is at the time specified in the applicable TR identified in table 2 to paragraph (g)(2) of this AD, or within 90 days after the effective date of this AD, whichever occurs later. ER26SE25.003 BILLING CODE 4910-13-C Note 1 to table 2 to paragraph (g)(2): The asterisk (or "one star") with the last three digits of the task numbers listed in table 2 to paragraph (g)(2) of this AD indicates that the task is an airworthiness limitation task. (h) Compliance Time Exception for a Certain Task For Bombardier, Inc., Model CL-600-2B16 (604 Variant) airplanes, S/Ns 5301 through 5665 inclusive and S/Ns 5701 through 6049 inclusive: The initial compliance time for task 27-42-01-110, "Special Detailed Inspection of the Horizontal Stabilizer Trim Actuator (HSTA), P/N 604-92305-7 and Subs (Vendor P/N 8454-3 and Subs)," of section 5-10-40, "Certification Maintenance Requirements," of Part 2, "Airworthiness Limitations," of Bombardier Challenger 604 TLMC, Publication No. CH 604 TLMC, Revision 33, dated November 22, 2022; or Bombardier Challenger 605 TLMC, Publication No. CH 605 TLMC, Revision 22, dated November 22, 2022; as applicable, is at the applicable compliance time specified in paragraph (h)(1) or (2) of this AD, or within 90 days after the effective date of this AD, whichever occurs later. (1) For HSTA having P/N 604-92305-3 (vendor P/N 8454-1) or P/N 604-92305-5 (vendor P/N 8454-2) that were replaced with P/N 604-92305-7 (vendor P/N 8454-3) in accordance with paragraph (j) of AD 2015-05-07, Amendment 39-18117 (80 FR 13483, March 16, 2015): Within 12 years after accomplishing the replacement. (2) For HSTA having P/N 604-92305-7 (vendor P/N 8454-3) manufactured before November 1, 2015: Within 12 years from the part entry into service. (i) No Alternative Actions and Intervals After the existing maintenance or inspection program has been revised as required by paragraph (g) of this AD, no alternative actions ( e.g., inspections) or intervals may be used unless the actions or intervals are approved as an alternative method of compliance (AMOC) in accordance with the procedures specified in paragraph (j)(1) of this AD. (j) Additional AD Provisions The following provisions also apply to this AD: (1) Alternative Methods of Compliance (AMOCs): The Manager, International Validation Branch, FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. In accordance with 14 CFR 39.19, send your request to your principal inspector or responsible Flight Standards Office, as appropriate. If sending information directly to the manager of the International Validation Branch, send it to the attention of the person identified in paragraph (k) of this AD and email to: AMOC@faa.gov . Before using any approved AMOC, notify your appropriate principal inspector, or lacking a principal inspector, the manager of the responsible Flight Standards Office. (2) Contacting the Manufacturer: For any requirement in this AD to obtain instructions from a manufacturer, the instructions must be accomplished using a method approved by the Manager, International Validation Branch, FAA; or Transport Canada; or Bombardier's Transport Canada Design Approval Organization (DAO). If approved by the DAO, the approval must include the DAO-authorized signature. (k) Additional Information For more information about this AD, contact Brenda L. Buitrago, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; phone: 516-228 7300; email: 9-avs-nyaco-cos@faa.gov . (l) Material Incorporated by Reference (1) The Director of the Federal Register approved the incorporation by reference of the material listed in this paragraph under 5 U.S.C. 552(a) and 1 CFR part 51. (2) You must use this material as applicable to do the actions required by this AD, unless this AD specifies otherwise. (i) Section 5-10-00, "Airworthiness Limitations," of Bombardier Challenger 600 Time Limits/Maintenance Checks (TLMC), Publication No. PSP 605, Revision 39, dated January 8, 2018. Note 2 to paragraph (l)(2)(i): For obtaining this section of Bombardier Challenger 600 TLMC, Publication No. PSP 605, use Document Identification No. CH 600 TLMC. (ii) Section 5-10-00, "Airworthiness Limitations," of Bombardier Challenger 601 TLMC, Publication No. PSP 601-5, Revision 46, dated January 8, 2018. Note 3 to paragraph (l)(2)(ii): For obtaining this section Bombardier Challenger 601 TLMC, Publication No. PSP 601-5, use Document Identification No. CH 601 TLMC. (iii) Section 5-10-00, "Airworthiness Limitations," of Bombardier Challenger 601 TLMC, Publication No. PSP 601A-5, Revision 42, dated January 8, 2018. Note 4 to paragraph (l)(2)(iii): For obtaining this section of Bombardier Challenger 601 TLMC, Publication No. PSP 601A-5, use Document Identification No. CH 601 TLMC-1. (iv) Part 2, "Airworthiness Limitations," of Bombardier Challenger 604 TLMC, Publication No. CH 604 TLMC, Revision 33, dated November 22, 2022. Note 5 to paragraph (l)(2)(iv): The document identification number for ordering Bombardier Challenger 604 TLMC, Publication No. CH 604 TLMC is incorrectly identified as "CH 600 TLMC" on page 2 of the TLMC. For obtaining Part 2 of Bombardier Challenger 604 TLMC, Publication No. CH 604 TLMC, use Document Identification No. CH 604 TLMC. (v) Part 2, "Airworthiness Limitations," of Bombardier Challenger 605 TLMC, Publication No. CH 605 TLMC, Revision 22, dated November 22, 2022. (vi) Part 2, "Airworthiness Limitations," of Bombardier Challenger 650 TLMC, Publication No. CH 650 TLMC, Revision 9, dated November 22, 2022. (vii) Bombardier Temporary Revision No. 5-2-5, dated October 16, 2023. (viii) Bombardier Temporary Revision No. 5-2-29, dated October 25, 2023. (ix) Bombardier Temporary Revision No. 5-2-73, dated October 25, 2023. (x) Bombardier Temporary Revision No. TR 5-164, dated December 23, 2022. (xi) Bombardier Temporary Revision No. TR 5-165, dated October 25, 2023. (xii) Bombardier Temporary Revision No. TR 5-268, dated December 23, 2022. (xiii) Bombardier Temporary Revision No. TR 5-269, dated October 25, 2023. (xiv) Bombardier Temporary Revision No. TR 5-282, dated December 23, 2022. (xv) Bombardier Temporary Revision No. TR 5-283, dated October 25, 2023. (3) For Bombardier material identified in this AD, contact Bombardier Business Aircraft Customer Response Center, 400 Côte-Vertu Road West, Dorval, Québec H4S 1Y9, Canada; telephone 514-855-2999; email ac.yul@aero.bombardier.com; website https://my.bombardier.com/ . (4) 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. (5) You may view this material at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, visit www.archives.gov/federal-register/cfr/ibr-locations or email fr.inspection@nara.gov . Issued on September 16, 2025. Steven W. Thompson, Acting Deputy Director, Compliance & Airworthiness Division, Aircraft Certification Service.