AD 2025-13-04

This AD is effective August 5, 2025.

The Director of the Federal Register approved the incorporation by reference of a certain publication listed in this AD as of August 5, 2025.

AD Docket: You may examine the AD docket at regulations.gov under Docket No. FAA-2025-0619; 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 address for Docket Operations is U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue SE, Washington, DC 20590.

Material Incorporated by Reference:

• 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 TC.AirworthinessDirectives-Consignesdenavigabilite.TC@tc.gc.ca. You may find this material on the Transport Canada website at tc.canada.ca/en/aviation.

• 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 regulations.gov under Docket No. FAA-2025-0619.

Isabel Saltzman, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; phone: 516-228-7300; email: 9-avs-nyaco-cos@faa.gov.

The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by adding an AD that would apply to all 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. The NPRM was published in the Federal Register on April 15, 2025 (90 FR 15664). The NPRM was prompted by AD CF-2024-25, dated June 28, 2024 (Transport Canada AD CF-2024-25) (also referred to as “the MCAI”), issued by Transport Canada, which is the aviation authority for Canada. The MCAI states that an in-service event occurred where an EICAS STAB TRIM Caution message was posted. Subsequent repair found prematurely worn teeth on an RBG wheel in the HSTA. Investigation determined that this quality issue affects a limited number of RBG wheels and HSTA serial numbers. Wear of the RBG wheel teeth could cause a failure of the horizontal stabilizer trim system.

In the NPRM, the FAA proposed to require an inspection for part numbers and on-condition replacement of affected RBG wheels, as specified in Transport Canada AD CF-2024-25. The NPRM also proposed to prohibit the installation of affected parts under certain conditions, as specified in Transport Canada AD CF-2024-25. The FAA is issuing 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-2025-0619.

The FAA received comments from Air Line Pilots Association, International, and an individual, who both supported the NPRM without change.

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. This AD is adopted as proposed in the NPRM.

The FAA reviewed Transport Canada AD CF-2024-25, which specifies procedures for a part number check and, if necessary, replacement of affected RBG wheels in certain HSTAs. Transport Canada AD CF-2025-24 also prohibits the installation of affected parts under certain conditions. 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.

The FAA estimates that this AD affects 460 airplanes of U.S. registry. The FAA estimates the following costs to comply with this AD:

The FAA estimates the following costs to do any on-condition replacement that would be required based on the results of determining whether the part is an affected part. The FAA has no way of determining the number of airplanes that might need this replacement:

The FAA has included all known costs in its cost estimate. According to the manufacturer, however, some or all of the costs of this AD may be covered under warranty, thereby reducing the cost impact on affected operators.

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.

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.

Accordingly, under the authority delegated to me by the Administrator, the FAA amends 14 CFR part 39 as follows:

1. The authority citation for part 39 continues to read as follows:

2. The FAA amends § 39.13 by adding the following new airworthiness directive: