Airworthiness Directives; Continental Aerospace Technologies GmbH Engines

[Federal Register Volume 90, Number 197 (Wednesday, October 15, 2025)]
[Rules and Regulations]
[Pages 48251-48254]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2025-19555]



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Federal Register / Vol. 90, No. 197 / Wednesday, October 15, 2025 / 
Rules and Regulations

[[Page 48251]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2025-3432; Project Identifier MCAI-2024-00743-E; 
Amendment 39-23171; AD 2025-20-18]
RIN 2120-AA64


Airworthiness Directives; Continental Aerospace Technologies GmbH 
Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule; request for comments.

-----------------------------------------------------------------------

SUMMARY: The FAA is adopting a new airworthiness directive (AD) for all 
Continental Aerospace Technologies GmbH (Continental) Model TAE 125-02-
125 engines. This AD was prompted by multiple reports of cracks in the 
cylinder heads, which can cause engine coolant to leak into the 
combustion chamber. This AD requires a one-time inspection of the 
engine coolant for contamination and, depending on the inspection 
results, replacement of the coolant and replacement of the cylinder 
heads. This AD also prohibits installing a cylinder head on any engine 
unless it is a serviceable part. The FAA is issuing this AD to address 
the unsafe condition on these products.

DATES: This AD is effective October 30, 2025.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in this AD as of October 30, 
2025.
    The FAA must receive comments on this AD by December 1, 2025.

ADDRESSES: You may send comments, using the procedures found in 14 CFR 
11.43 and 11.45, by any of the following methods:
    <bullet> Federal eRulemaking Portal: Go to regulations.gov. Follow 
the instructions for submitting comments.
    <bullet> Fax: (202) 493-2251.
    <bullet> 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.
    <bullet> 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-2025-3432; 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.
    Material Incorporated by Reference:
    <bullet> For Continental material identified in this AD, contact 
Continental, Platanenstrasse 14, 09356 Sankt Egidien, Germany; phone: 
+49 37204 696 0; email: continentaldiesel.com">support@continentaldiesel.com; website: 
continentaldiesel.com.
    <bullet> You may view this material at the FAA, Operational Safety 
Branch, 1200 District Avenue, Burlington, MA 01803. For information on 
the availability of this material at the FAA, call (817) 222-5110. It 
is also available at regulations.gov under Docket No. FAA-2025-3432.

FOR FURTHER INFORMATION CONTACT: Rawle Thomas, Aviation Safety 
Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; 
phone: (404) 474-5576; email: [email protected].

SUPPLEMENTARY INFORMATION:

Comments Invited

    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 ADDRESSES section. Include ``Docket No. FAA-2025-3432; Project 
Identifier MCAI-2024-00743-E'' 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 
regulations.gov, including any personal information you provide. The 
agency will also post a report summarizing each substantive verbal 
contact received about this final rule.

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 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 Rawle 
Thomas, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, 
Westbury, NY 11590. Any commentary that the FAA receives which is not 
specifically designated as CBI will be placed in the public docket for 
this rulemaking.

Background

    The European Union Aviation Safety Agency (EASA), which is the 
Technical Agent for the Member States of the European Union, has issued 
EASA AD 2024-0236, dated December 10, 2024 (EASA AD 2024-0236) (also 
referred to as the MCAI), to correct an unsafe condition on all 
Continental Model TAE 125-02-125 engines. The MCAI states that several 
cases of cracks in cylinder heads have been reported. The MCAI further 
states that these cracks may cause leakage of engine coolant into the 
combustion chamber(s), causing loss of coolant, which could lead to 
engine overheat and eventual engine failure or seizure. Additionally, 
the MCAI states that contamination of the engine coolant, especially 
with potassium, triggers certain critical types of chemical corrosion, 
depending on the nature of such contamination. The investigation of the 
root cause for the cylinder head

[[Page 48252]]

ruptures is still ongoing. Accordingly, the MCAI is considered an 
interim action.
    This condition, if not addressed, could result in an uncommanded 
in-flight shutdown of the engine and a forced landing, which could 
result in damage to the airplane and injury to occupants.
    You may examine the MCAI in the AD docket at regulations.gov under 
Docket No. FAA-2025-3432.

Material Incorporated by Reference Under 1 CFR Part 51

    The FAA reviewed Continental Service Bulletin (SB) CG 125-1030 P1, 
Revision 4, dated January 10, 2025. This material specifies procedures 
for a one-time inspection of the engine coolant for contamination using 
the minimum and maximum acceptable ranges for the two coolant types as 
specified in the material. This material also specifies procedures for 
labeling the coolant samples.
    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 AD after determining that the unsafe condition described 
previously is likely to exist or develop on other products of the same 
type design.

AD Requirements

    This AD requires a one-time inspection of the engine coolant for 
contamination and, depending on the results, replacing the cylinder 
heads with a serviceable part for engines in which the coolant sample 
has aluminum or fluoride that exceeds the acceptable range; or draining 
and flushing the engine cooling system and refilling it with new 
coolant for engines in which the coolant sample exceeds any acceptable 
range, except for aluminum and fluoride. This AD also prohibits 
installing a cylinder head on any engine unless it is a serviceable 
part.

Interim Action

    The FAA considers this AD interim action. The unsafe condition is 
still under investigation by the manufacturer. If final action is later 
identified, the FAA might consider further rulemaking.

Justification for Immediate Adoption and Determination of the Effective 
Date

    Section 553(b) of the Administrative Procedure Act (APA) (5 U.S.C. 
551 et seq.) authorizes agencies to dispense with notice and comment 
procedures for rules when the agency, for ``good cause,'' finds that 
those procedures are ``impracticable, unnecessary, or contrary to the 
public interest.'' Under this section, an agency, upon finding good 
cause, may issue a final rule without providing notice and seeking 
comment prior to issuance. Further, section 553(d) of the APA 
authorizes agencies to make rules effective in less than thirty days, 
upon a finding of good cause.
    An unsafe condition exists that requires the immediate adoption of 
this AD without providing an opportunity for public comments prior to 
adoption. The FAA has found that the risk to the flying public 
justifies forgoing notice and comment prior to adoption of this rule 
because contamination of the engine coolant can cause chemical 
corrosion, which could lead to cracks in the cylinder heads and allow 
engine coolant to leak into the combustion chamber. Additionally, 
cylinder heads are critical components to maintaining controlled 
flight. The FAA has no information pertaining to the root cause, the 
extent of the root cause that may currently exist in airplanes, or how 
quickly the root cause may propagate to failure. Additionally, the 
compliance time in this AD for the required actions is within 5 flight 
hours (FH) for engines with 50 FH or more since the last engine coolant 
replacement or since new, which is shorter than the time necessary for 
the public to comment and for publication of the final rule. 
Accordingly, notice and opportunity for prior public comment are 
impracticable and contrary to the public interest pursuant to 5 U.S.C. 
553(b).
    In addition, the FAA finds that good cause exists pursuant to 5 
U.S.C. 553(d) for making this amendment effective in less than 30 days, 
for the same reasons the FAA found good cause to forgo notice and 
comment.

Regulatory Flexibility Act

    The requirements of the Regulatory Flexibility Act (RFA) do not 
apply when an agency finds good cause pursuant to 5 U.S.C. 553 to adopt 
a rule without prior notice and comment. Because the FAA has determined 
that it has good cause to adopt this rule without prior notice and 
comment, RFA analysis is not required.

Costs of Compliance

    The FAA estimates that this AD affects 30 engines installed on 
airplanes of U.S. registry.
    The FAA estimates the following costs to comply with this AD:

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                                     Cost per      Cost on U.S.
               Action                         Labor cost            Parts cost        product        operators
----------------------------------------------------------------------------------------------------------------
Inspect coolant....................  2 work-hours x $85 per hour              $0            $170          $5,100
                                      = $170.
----------------------------------------------------------------------------------------------------------------

    The FAA estimates the following costs to do any necessary actions 
that would be required based on the results of the inspection. The 
agency has no way of determining the number of engines that might need 
these actions:

                                               On-Condition Costs
----------------------------------------------------------------------------------------------------------------
                                                                                                     Cost per
                    Action                                 Labor cost               Parts cost        product
----------------------------------------------------------------------------------------------------------------
Drain, flush engine cooling system, and         4 work-hours x $85 per hour =                $20            $360
 replace coolant.                                $340.
Replace cylinder head.........................  16 work-hours x $85 per hour =            10,000          11,360
                                                 $1,360.
----------------------------------------------------------------------------------------------------------------


[[Page 48253]]

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, and
    (2) Will not affect intrastate aviation in Alaska.

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:

2025-20-18 Continental Aerospace Technologies GmbH: Amendment 39-
23171; Docket No. FAA-2025-3432; Project Identifier MCAI-2024-00743-
E.

(a) Effective Date

    This airworthiness directive (AD) is effective October 30, 2025.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to Continental Aerospace Technologies GmbH 
(Continental) Model TAE 125-02-125 engines.

(d) Subject

    Joint Aircraft System Component (JASC) Code 1240, Coolant 
Servicing.

(e) Unsafe Condition

    This AD was prompted by multiple reports of cracks in the 
cylinder heads, which can cause engine coolant to leak into the 
combustion chamber. The root cause of this damage is unknown, and 
the investigation is ongoing. The FAA is issuing this AD to detect 
and correct contamination of the engine coolant. The unsafe 
condition, if not addressed, could result in an uncommanded in-
flight shutdown of the engine and a forced landing, which could 
result in damage to the airplane and injury to occupants.

(f) Compliance

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

(g) Definition

    (1) For the purpose of this AD, a ``serviceable part'' is a 
cylinder head which is new (never installed), or a cylinder head 
which was not removed in accordance with paragraph (h)(2) of this 
AD.

(h) Required Actions

    (1) Inspect (sampling and analysis) the engine coolant for 
contamination in accordance with Appendix B: Instruction to take 
coolant sample, of Continental Service Bulletin CG 125-1030 P1, 
Revision 4, dated January 10, 2025 (SB CG 125-1030 P1, Rev 4), at 
the applicable time in paragraph (h)(1)(i) or (ii) of this AD:
    (i) For engines that have accumulated 50 flight hours (FH) or 
more since the last engine coolant replacement or 50 FH or more 
since new if the coolant has never been replaced, as of the 
effective date of this AD, within 5 FH after the effective date of 
this AD.
    (ii) For engines that have accumulated less than 50 FH since the 
last engine coolant replacement or less than 50 FH since new if the 
coolant has never been replaced, as of the effective date of this 
AD, within 5 FH after accumulating 50 FH.
    (2) If, during any inspection required by paragraph (h)(1) of 
this AD, the coolant sample contains aluminum or fluoride that 
exceeds the acceptable range as specified in Table 1: Limit values 
for G48 coolant type or Table 2: Limit values for G40 coolant type, 
as applicable, in Appendix A: Material, Methods and Limits, of SB CG 
125-1030 P1, Rev 4, before further flight, remove the cylinder head 
and replace it with a serviceable part, flush the engine cooling 
system, and refill the cooling system with new coolant.
    (3) If, during any inspection required by paragraph (h)(1) of 
this AD, the coolant sample exceeds any acceptable range, except for 
the aluminum or fluoride ranges, as specified in Table 1: Limit 
values for G48 coolant type or Table 2: Limit values for G40 coolant 
type, as applicable, in Appendix A: Material, Methods and Limits, of 
SB CG 125-1030 P1, Rev 4, before further flight, drain and flush the 
engine cooling system and refill the cooling system with new 
coolant.

(i) Installation Prohibition

    After the effective date of this AD, do not install on any 
engine a cylinder head that is not a ``serviceable part,'' as 
defined in paragraph (g)(1) of this AD.

(j) Credit for Previous Actions

    This paragraph provides credit for the inspections and part 
replacements required by paragraph (h) of this AD, if those actions 
were performed before the effective date of this AD using 
Continental Service Bulletin CG 125-1030 P1, Revision 3, dated 
September 16, 2024.

(k) Alternative Methods of Compliance (AMOCs)

    (1) 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 local Flight 
Standards District 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 (l) of 
this AD and email to [email protected].
    (2) Before using any approved AMOC, notify your appropriate 
principal inspector, or lacking a principal inspector, the manager 
of the local flight standards district office/certificate holding 
district office.

(l) Additional Information

    (1) For more information about this AD, contact Rawle Thomas, 
Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, 
Westbury, NY 11590; phone: (404) 474-5576; email: 
[email protected].
    (2) For Continental material, which is not incorporated by 
reference in this AD, contact Continental, Platanenstrasse 14, 09356 
Sankt Egidien, Germany; phone: +49 37204 696 0; email: 
continentaldiesel.com">support@continentaldiesel.com; website: continentaldiesel.com.

(m) 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 the AD specifies otherwise.
    (i) Continental Aerospace Technologies GmbH (Continental) 
Service Bulletin CG 125-1030 P1, Revision 4, dated January 10, 2025.
    (ii) [Reserved]
    (3) For Continental material identified in this AD, contact 
Continental, Platanenstrasse 14, 09356 Sankt Egidien, Germany; 
phone:

[[Page 48254]]

+49 37204 696 0; email: continentaldiesel.com">support@continentaldiesel.com; website: 
continentaldiesel.com.
    (4) You may view this material at the FAA, Operational Safety 
Branch, 1200 District Avenue, Burlington, MA 01803. For information 
on the availability of this material at the FAA, call (817) 222-
5110.
    (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 [email protected].

    Issued on October 3, 2025.
Steven W. Thompson,
Acting Deputy Director, Compliance & Airworthiness Division, Aircraft 
Certification Service.
[FR Doc. 2025-19555 Filed 10-14-25; 8:45 am]
BILLING CODE 4910-13-P

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