# [Amended]
**AGENCY:**
Federal Aviation Administration (FAA), DOT.
**ACTION:**
Notice of proposed rulemaking (NPRM).
**SUMMARY:**
The FAA proposes to supersede Airworthiness Directive (AD) 2025-17-12, which applies 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. AD 2025-17-12 requires revising the existing maintenance or inspection program, as applicable, to incorporate new or more restrictive airworthiness limitations. Since the FAA issued AD 2025-17-12, the FAA has determined that certain serial numbers for affected Model CL-600-2B16 (604 Variants) airplanes are not included in the applicability of AD 2025-17-12. This proposed AD would continue to require the actions specified in AD 2025-17-12 and would add airplanes to the applicability. The FAA is proposing this AD to address the unsafe condition on these products.
**DATES:**
The FAA must receive comments on this NPRM by November 20, 2025.
**ADDRESSES:**
You may send comments, using the procedures found in 14 CFR 11.43 and 11.45, by any of the following methods:
• *Federal eRulemaking Portal:* Go to *regulations.gov* . Follow the instructions for submitting comments.
• *Fax:* 202-493-2251.
• *Mail:* U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue SE, Washington, DC 20590.
• *Hand Delivery:* Deliver to Mail address above between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.
*AD Docket:* You may examine the AD docket at *regulations.gov* under Docket No. FAA-2025-3435; 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 NPRM, the mandatory continuing airworthiness information (MCAI), any comments received, and other information. The street address for Docket Operations is listed above.
*Material Incorporated by Reference:*
• For Bombardier material identified in this proposed AD, contact Bombardier Business Aircraft Customer Response Center, 400 Côte-Vertu Road West, Dorval, Québec H4S 1Y9, Canada; telephone 514-855-2999; email *[email protected];* website *https://my.bombardier.com/.*
• 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.
**FOR FURTHER INFORMATION CONTACT:**
Brenda L. Buitrago, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; phone: 516-228-7300; email: *[email protected].*
**SUPPLEMENTARY INFORMATION:**
**Comments Invited**
The FAA invites you to send any written relevant data, views, or arguments about this proposal. Send your comments using a method listed under the *ADDRESSES* section. Include “Docket No. FAA-2025-3435; Project Identifier MCAI-2025-01602-T” at the beginning of your comments. The most helpful comments reference a specific portion of the proposal, 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 the proposal 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 *regulations.gov,* including any personal information you provide. The agency will also post a report summarizing each substantive verbal contact received about this NPRM.
**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 this NPRM 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 NPRM, 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 NPRM. Submissions containing CBI should be sent to Brenda L. Buitrago, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; phone: 516-228-7300; email: *[email protected].* Any commentary that the FAA receives that is not specifically designated as CBI will be placed in the public docket for this rulemaking.
**Background**
The FAA issued AD 2025-17-12, Amendment 39-23122 (90 FR 46330, September 26, 2025) (AD 2025-17-12), for 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. AD 2025-17-12 was prompted by an MCAI originated by Transport Canada, which is the aviation authority for Canada. Transport Canada issued AD CF-2024-16, dated May 23, 2024 (Transport Canada AD CF-2024-16), to correct an unsafe condition.
AD 2025-17-12 requires revising the existing maintenance or inspection program, as applicable, to incorporate new or more restrictive airworthiness limitations. The FAA issued AD 2025-17-12 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.
**Actions Since AD 2025-17-12 Was Issued**
Since the FAA issued AD 2025-17-12, the FAA has determined that certain serial numbers for affected Model CL-600-2B16 (604 Variant) airplanes are not included in the applicability of AD 2025-17-12. Table 1 to paragraph (g)(1) of AD 2025-17-12 and table 2 to paragraph (g)(2) of AD 2025-17-12 identify the applicable airplanes for each document by serial numbers. For Model CL-600-2B16 (604 Variant) airplanes, the serial numbers start at 5301. However, paragraph (c)(2) of AD 2025-17-12 only identifies Model CL-600-2B16 (604 Variant) airplanes, serial numbers (S/Ns) 6050 through 6192 inclusive. Therefore, the FAA is revising the applicability of this proposed AD by adding Model CL-600-2B16 (604 Variant) airplanes, S/Ns 5301 through 5665 inclusive and S/Ns 5701 through 6049 inclusive. The FAA has removed references to those serial numbers from table 1 to paragraph (g)(1) of this proposed AD and table 2 to paragraph (g)(2) of this proposed AD and added actions for those airplanes to paragraph (i) of this proposed AD.
The FAA has also determined that the last row of table 2 to paragraph (g)(2) of AD 2025-17-12 inadvertently lists S/N 6193 instead of S/N 6192. Airplanes having S/N 6193 and subsequent were delivered with Bombardier Temporary Revision No. 5-2-5, dated October 16, 2023, and must comply with the airworthiness limitations specified as part of the approved type design. The FAA has revised table 2 to paragraph (g)(2) of this proposed AD accordingly.
The FAA is proposing this AD to address the unsafe condition on these products.
You may examine the MCAI in the AD docket at *regulations.gov* under Docket No. FAA-2025-3435.
**Material Incorporated by Reference Under 1 CFR Part 51**
This proposed AD would require the following Bombardier material, which the Director of the Federal Register approved for incorporation by reference as of October 31, 2025 (90 FR 46333, September 26, 2025):
• 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.
• 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.)
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.
**FAA's Determination**
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 and material referenced above. The FAA is issuing this NPRM after determining that the unsafe condition described previously is likely to exist or develop on other products of the same type design.
**Proposed Requirements of This NPRM**
This proposed AD would retain all of the requirements of AD 2025-17-12. This proposed AD would also add airplanes to the applicability.
This proposed AD would require revisions to certain operator maintenance documents to include new actions ( *e.g.,* inspections). Compliance with these actions is required by 14 CFR 91.403(c). For airplanes that have been previously modified, altered, or repaired in the areas addressed by this proposed AD, the operator may not be able to accomplish the actions described in the revisions. In this situation, to comply with 14 CFR 91.403(c), the operator must request approval for an alternative method of compliance according to paragraph (l)(1) of this proposed AD.
**Costs of Compliance**
The FAA estimates that this AD, if adopted as proposed, would affect 427 airplanes of U.S. registry. The FAA estimates the following costs to comply with this proposed AD:
The FAA estimates the total cost per operator for the retained actions from AD 2025-17-12 to be $7,650 (90 work-hours × $85 per work-hour).
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 FAA estimates the total cost per operator for the new proposed actions to be $7,650 (90 work-hours × $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**
The FAA determined that this proposed AD would not have federalism implications under Executive Order 13132. This proposed AD would 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 this proposed regulation:
(1) Is not a “significant regulatory action” under Executive Order 12866,
(2) Would not affect intrastate aviation in Alaska, and
(3) Would 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 Proposed Amendment**
Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 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
2. The FAA amends § 39.13 by:
a. Removing Airworthiness Directive 2025-17-12, Amendment 39-23122 (90 FR 46330, September 26, 2025); and
b. Adding the following new airworthiness directive:
*Bombardier, Inc.:* Docket No. FAA-2025-3435; Project Identifier MCAI-2025-01602-T.
**(a) Comments Due Date**
The FAA must receive comments on this airworthiness directive (AD) by November 20, 2025.
**(b) Affected ADs**
This AD replaces AD 2025-17-12, Amendment 39-23122 (90 FR 46330, September 26, 2025) (AD 2025-17-12).
**(c) Applicability**
This AD applies to the Bombardier, Inc., airplanes identified in paragraphs (c)(1) through (3) 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 (S/Ns) 5301 through 5665 inclusive and S/Ns 5701 through 6049 inclusive.
(3) Model CL-600-2B16 (604 Variant) airplanes, S/Ns 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) Retained Revision of the Existing Maintenance or Inspection Program for Certain Airplanes, With Removal of References to S/Ns 5301 Through 6049 Inclusive**
This paragraph restates the requirements of paragraph (g) of AD 2025-17-12, with removal of references to S/Ns 5301 through 6049 inclusive. For airplanes identified in paragraphs (c)(1) and (3) of this AD, comply with paragraphs (g)(1) and (2) of this AD.
(1) Within 90 days after October 31, 2025 (the effective date of AD 2025-17-12), 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 October 31, 2025, whichever occurs later.
| Applicable airplanes | TLMC sections or parts | TLMC document |
| --- | --- | --- |
| Bombardier, Inc., Model CL-600-1A11 (600) airplanes, serial numbers (S/Ns) 1004 through 1085 inclusive | Section 5-10-00, “Airworthiness Limitations,” | Bombardier Challenger 600 TLMC, Publication No. PSP 605, Revision 39, January 8, 2018. |
| Bombardier, Inc., Model CL-600-2A12 (601) airplanes, S/Ns 3001 through 3066 inclusive | Section 5-10-00, “Airworthiness Limitations,” | Bombardier Challenger 601 TLMC, Publication No. PSP 601-5, Revision 46, January 8, 2018. |
| Bombardier, Inc., Model CL-600-2B16 (601-3A Variant) airplanes, S/Ns 5001 through 5134 inclusive; and Model CL-600-2B16 (601-3R Variant) airplanes, S/Ns 5135 through 5194 inclusive | Section 5-10-00, “Airworthiness Limitations,” | Bombardier Challenger 601 TLMC, Publication No. PSP 601A-5, Revision 42, January 8, 2018. |
| Bombardier, Inc., Model CL-600-2B16 (604 Variant) airplanes, S/Ns 6050 through 6180 inclusive | Part 2, “Airworthiness Limitations” | Bombardier Challenger 650 TLMC, Publication No. CH 650 TLMC, Revision 9, November 22, 2022. |
(2) Within 90 days after October 31, 2025 (the effective date of AD 2025-17-12), 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 October 31, 2025, whichever occurs later.
| Applicable airplanes | TR | Task No. and Title or life limit Part No. (P/N) and name |
| --- | --- | --- |
| Bombardier, Inc., Model CL-600-1A11 (600) airplanes, S/Ns 1004 through 1085 inclusive | Bombardier Temporary Revision No. TR 5-164, dated December 23, 2022 | 53-10-01-102*, Forward Pressure Bulkhead Cap Angle—Aft Side. |
| Bombardier, Inc., Model CL-600-1A11 (600) airplanes, S/Ns 1004 through 1085 inclusive | Bombardier Temporary Revision No. TR 5-165, dated October 25, 2023 | B0201102-2-220, Rudder Pedal Potentiometer Coupling Setscrews. |
| Bombardier, Inc., Model CL-600-2A12 (601) airplanes, S/Ns 3001 through 3066 inclusive | Bombardier Temporary Revision No. TR 5-268, dated December 23, 2022 | 53-10-01-103*, Forward Pressure Bulkhead Cap Angle—Aft Side. |
| Bombardier, Inc., Model CL-600-2A12 (601) airplanes, S/Ns 3001 through 3066 inclusive | Bombardier Temporary Revision No. TR 5-269, dated October 25, 2023 | B0201102-2-220, Rudder Pedal Potentiometer Coupling Setscrews. |
| Bombardier, Inc., Model CL-600-2B16 (601-3A Variant) airplanes, S/Ns 5001 through 5134 inclusive; and Model CL-600-2B16 (601-3R Variant) airplanes, S/Ns 5135 through 5194 inclusive | Bombardier Temporary Revision No. TR 5-282, dated December 23, 2022 | 53-10-01-103*, Forward Pressure Bulkhead Cap Angle—Aft Side. |
| Bombardier, Inc., Model CL-600-2B16 (601-3A Variant) airplanes, S/Ns 5001 through 5134 inclusive; and Model CL-600-2B16 (601-3R Variant) airplanes, S/Ns 5135 through 5194 inclusive | Bombardier Temporary Revision No. TR 5-283, dated October 25, 2023 | B0201102-2-220, Rudder Pedal Potentiometer Coupling Setscrews. |
| Bombardier, Inc., Model CL-600-2B16 (604 Variant) airplanes, S/Ns 6050 through 6192, inclusive | Bombardier Temporary Revision No. 5-2-5, dated October 16, 2023 | 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). |
*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) Retained No Alternative Actions and Intervals, With No Changes**
This paragraph restates the requirements of paragraph (i) of AD 2025-17-12, with no changes. 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 (l)(1) of this AD
**(i) New Revision of the Existing Maintenance or Inspection Program for Certain Airplanes**
For airplanes identified in paragraph (c)(2) of this AD: Comply with paragraphs (i)(1) and (2) of this AD.
(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 TLMC document identified in table 3 to paragraph (i)(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 3 to paragraph (i)(1) of this AD, or within 90 days after the effective date of this AD, whichever occurs later, except as provided by paragraph (j) of this AD.
| Applicable airplanes | TLMC sections or parts | TLMC document |
| --- | --- | --- |
| Bombardier, Inc., Model CL-600-2B16 (604 Variant) airplanes, S/Ns 5301 through 5665 inclusive | Part 2, “Airworthiness Limitations” | Bombardier Challenger 604 TLMC, Publication No. CH 604 TLMC, Revision 33, November 22, 2022. |
| Bombardier, Inc., Model CL-600-2B16 (604 Variant) airplanes, S/Ns 5701 through 6049 inclusive | Part 2, “Airworthiness Limitations” | Bombardier Challenger 605 TLMC, Publication No. CH 605 TLMC, Revision 22, November 22, 2022. |
(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 TRs identified in table 4 to paragraph (i)(2) of this AD. The initial compliance time for doing the tasks is at the time specified in the applicable TR identified in table 4 to paragraph (i)(2) of this AD, or within 90 days after the effective date of this AD, whichever occurs later.
| Applicable airplanes | TR | Task No. and title or life limit Part No. (P/N) and name |
| --- | --- | --- |
| Bombardier, Inc., Model CL-600-2B16 (604 Variant) airplanes, S/Ns 5301 through 5665 inclusive | Bombardier Temporary Revision No. 5-2-73, dated October 25, 2023 | 32-51-04-101*, Discard of the Nosewheel-Steering Control Potentiometer Coupling Setscrews, Part No. B0201102-2-220 (Post SB 604-32-033). |
| Bombardier, Inc., Model CL-600-2B16 (604 Variant) airplanes, S/Ns 5701 through 6049 inclusive | Bombardier Temporary Revision No. 5-2-29, dated October 25, 2023 | 32-51-04-101*, Discard of the Nosewheel-Steering Control Potentiometer Coupling Setscrews, Part No. B0201102-2-220 (Post SB 605-32-010). |
*Note 2 to table 4 to paragraph (i)(2):* The asterisk (or “one star”) with the last three digits of the task numbers listed in table 4 to paragraph (i)(2) of this AD indicates that the task is an airworthiness limitation task.
**(j) Compliance Time Exception for a Certain Task**
For airplanes identified in paragraph (c)(2) of this AD: 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 (j)(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.
**(k) New No Alternative Actions or Intervals**
After the existing maintenance or inspection program has been revised as required by paragraph (i) of this AD, no alternative actions ( *e.g.,* inspections) or intervals may be used unless the actions or intervals are approved as an AMOC in accordance with the procedures specified in paragraph (l)(1) of this AD.
**(l) 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 (m) of this AD and email to: *[email protected]* . 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.
**(m) 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: *[email protected].*
**(n) Material Incorporated by Reference**
(1) The Director of the Federal Register approved the incorporation by reference (IBR) 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.
(3) The following material was approved for IBR on October 31, 2025 (90 FR 46330, September 26, 2025).
(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 3 to paragraph (n)(3)(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 4 to paragraph (n)(3)(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 5 to paragraph (n)(3)(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 6 to paragraph (n)(3)(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.
(4) 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 *[email protected];* website *https://my.bombardier.com/.*
(5) 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.
(6) 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 * [email protected].*
Issued on October 16, 2025.
Christopher R. Parker,
Acting Deputy Director, Compliance & Airworthiness Division, Aircraft Certification Service.