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

[Federal Register Volume 90, Number 124 (Tuesday, July 1, 2025)]
[Rules and Regulations]
[Pages 27977-27979]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2025-12245]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2025-0619; Project Identifier MCAI-2024-00372-T; 
Amendment 39-23070; AD 2025-13-04]
RIN 2120-AA64


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

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for all 
MHI RJ Aviation ULC 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 an engine 
indicating and crew alerting system (EICAS) STAB TRIM Caution message 
that was posted, and subsequent repair that found prematurely worn 
teeth on a rubber bull gear (RBG) wheel in the horizontal stabilizer 
trim actuator (HSTA). This AD requires an inspection for part numbers 
and on-condition replacement of affected RBG wheels. This AD also 
prohibits the installation of affected parts under certain conditions. 
The FAA is issuing this AD to address the unsafe condition on these 
products.

DATES: 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.

ADDRESSES: 
    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:
    <bullet> 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 [email protected]. You may find this material on the 
Transport Canada website at tc.canada.ca/en/aviation.
    <bullet> 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.

FOR FURTHER INFORMATION CONTACT: Isabel Saltzman, Aviation Safety 
Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; 
phone: 516-228-7300; email: [email protected].

SUPPLEMENTARY INFORMATION:

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 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.

Discussion of Final Airworthiness Directive

Comments

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

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. This AD is 
adopted as proposed in the NPRM.

Material Incorporated by Reference Under 1 CFR Part 51

    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.

Costs of Compliance

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

[[Page 27978]]



                                      Estimated Costs for Required Actions
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               Labor cost                         Parts cost           Cost per product   Cost on U.S. operators
----------------------------------------------------------------------------------------------------------------
1 work-hour x $85 per hour = $85.......  None.......................                $85                  $39,100
----------------------------------------------------------------------------------------------------------------

    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:

                 Estimated Costs of On-Condition Actions
------------------------------------------------------------------------
            Labor cost              Parts cost      Cost per product
------------------------------------------------------------------------
30 work-hours x $85 per hour =            * $0  At least $2,550 (up to
 $2,550.                                         32 affected parts in
                                                 the fleet).
------------------------------------------------------------------------
* The FAA has received no definitive data on which to base the cost
  estimates for the on-condition parts specified in this AD.

    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.

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

0
1. The authority citation for part 39 continues to read as follows:

    Authority:  49 U.S.C. 106(g), 40113, 44701.


Sec.  39.13  [Amended]

0
2. The FAA amends Sec.  39.13 by adding the following new airworthiness 
directive:

2025-13-04 MHI RJ Aviation ULC (Type Certificate Previously Held by 
Bombardier Inc.): Amendment 39-23070; Docket No. FAA-2025-0619; 
Project Identifier MCAI-2024-00372-T.

(a) Effective Date

    This airworthiness directive (AD) is effective August 5, 2025.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to all MHI RJ Aviation ULC (Type Certificate 
previously held by Bombardier Inc.) airplanes identified in 
paragraphs (c)(1) through (5) of this AD, certificated in any 
category.
    (1) Model CL-600-2C10 (Regional Jet Series 700, 701, & 702) 
airplanes.
    (2) Model CL-600-2C11 (Regional Jet Series 550) airplanes.
    (3) Model CL-600-2D15 (Regional Jet Series 705) airplanes.
    (4) Model CL-600-2D24 (Regional Jet Series 900) airplanes.
    (5) Model CL-600-2E25 (Regional Jet Series 1000) airplanes.

(d) Subject

    Air Transport Association (ATA) of America Code 27, Flight 
Controls.

(e) Unsafe Condition

    This AD was prompted by a report of an in-service event where an 
engine indicating and crew alerting system STAB TRIM Caution message 
was posted, and subsequent repair found prematurely worn teeth on a 
rubber bull gear (RBG) wheel in the horizontal stabilizer trim 
actuator. The FAA is issuing this AD to address premature wear of 
the RBG wheel teeth. The unsafe condition, if not addressed, could 
result in a failure of the horizontal stabilizer trim system.

(f) Compliance

    Comply with this AD within the compliance times specified, 
unless already done.

(g) Requirements

    Except as specified in paragraphs (h) and (i) of this AD: Comply 
with all required actions and compliance times specified in, and in 
accordance with, Transport Canada AD CF-2024-25, dated June 28, 2024 
(Transport Canada AD CF-2024-25).

(h) Exceptions to Transport Canada AD CF-2024-25

    (1) Where Transport Canada AD CF-2024-25 refers to its effective 
date, this AD requires using the effective date of this AD.
    (2) Where Transport Canada AD CF-2024-25 refers to ``Section 
1.A. of the applicable MHIRJ SB'', this AD requires replacing that 
text with ``Section 1.A. of MHIRJ Service Bulletin 670BA-27-077, 
dated April 16, 2024''.

(i) 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

[[Page 27979]]

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 (j) 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 MHI RJ's Transport 
Canada Design Approval Organization (DAO). If approved by the DAO, 
the approval must include the DAO-authorized signature.

(j) Additional Information

    For more information about this AD, contact Isabel Saltzman, 
Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, 
Westbury, NY 11590; phone: 516-228-7300; email: [email protected].

(k) 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) Transport Canada AD CF-2024-25, dated June 28, 2024.
    (ii) [Reserved]
    (3) 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 [email protected]. You may find this material on 
the Transport Canada website at tc.canada.ca/en/aviation.
    (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/[email protected]">www.archives.gov/federal-register/cfr/[email protected].

    Issued on June 18, 2025.
Steven W. Thompson,
Acting Deputy Director, Compliance & Airworthiness Division, Aircraft 
Certification Service.
[FR Doc. 2025-12245 Filed 6-30-25; 8:45 am]
BILLING CODE 4910-13-P

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