2025-20-18: Coolant Servicing

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: 2025-20-18 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: [email protected]; 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: +49 37204 696 0; email: [email protected]; 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