Background The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to supersede AD 2020-24-07, Amendment 39-21337 (85 FR 78954, December 8, 2020) (AD 2020-24-07). AD 2020-24-07 applied to Airbus Helicopters Model AS350B3 helicopters with an ARRIEL 2B1 engine with the two-channel Full Authority Digital Engine Control (FADEC) and with new twist grip modification (MOD) 073254 or with an ARRIEL 2D engine installed; Model EC130B4 helicopters with an ARRIEL 2B1 engine with the two-channel FADEC and with new twist grip MOD 073773 installed; and Model EC130T2 helicopters with an ARRIEL 2D engine installed. AD 2020-24-07 required repetitively inspecting the wiring, performing an insulation test, inspecting the pilot and copilot twist grip controls, and testing the pilot and copilot twist grip controls for proper functioning. The FAA issued AD 2020-24-07 to prevent the failure of one of the microswitches, 53Ka, 53Kb, or 65K, which can prevent switching from "IDLE" mode to "FLIGHT" mode during autorotation training making it impossible to recover from a practice autorotation and compelling the pilot to continue the autorotation to the ground. This condition could result in unintended touchdown to the ground at a flight-idle power setting during a practice autorotation, damage to the helicopter, and injury to occupants. The NPRM was published in the Federal Register on June 20, 2025 (90 FR 26225). The NPRM was prompted by AD 2023-0133, dated July 5, 2023, issued by EASA, which is the Technical Agent for the Member States of the European Union (EASA AD 2023-0133). EASA AD 2023-0133 states that Airbus Helicopters developed MOD 074782, introducing a new engine power control assembly with microswitches 53Ka, 53Kb, and 65K, and mandating installation of a serviceable assembly, while prohibiting installation of an affected microswitch on any helicopter. EASA AD 2023-0133 also expands the applicability to all serial numbers of Airbus Helicopters Model AS 350 B3, EC 130 B4, and EC 130 T2 helicopters. EASA then superseded AD 2023-0133 and issued EASA AD 2023-0187, dated October 27, 2023 (EASA AD 2023-0187). EASA AD 2023-0187 states that errors were found in the modification installation procedure and requires amending the modification instructions and additional work for certain helicopters already modified. EASA then superseded AD 2023-0187 and issued EASA AD 2023-0187R1, dated March 20, 2025 (EASA AD 2023-0187R1) (also referred to as the MCAI), to correct an unsafe condition for all Airbus Helicopters Model AS 350 B3, EC 130 B4, and EC 130 T2 helicopters. The MCAI states that the salt-laden atmospheric condition definition should be re-formulated, adjusting to the less restrictive description provided in the applicable aircraft maintenance manual. The FAA did not issue an AD corresponding to EASA AD 2023-0133 and EASA AD 2023-0187. In the NPRM, the FAA proposed to retain the actions required by AD 2020-24-07 and mandate an additional modification, which would constitute terminating action for the repetitive inspections. In the NPRM, the FAA also proposed to expand the helicopter applicability, provide additional requirements for certain helicopters, and prohibit installation of affected microswitches or an affected twist grip with the affected microswitch. You may examine the MCAI in the AD docket at regulations.gov under Docket No. FAA-2025-1108. Discussion of Final Airworthiness Directive Comments The FAA received no comments on the NPRM or on the determination of the costs. 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. Except for minor editorial changes, this AD is adopted as proposed in the NPRM. None of the changes will increase the economic burden on any operator. Material Incorporated by Reference Under 1 CFR Part 51 The FAA reviewed EASA AD 2023-0187R1, which specifies procedures for modifying the twist grip operational logic on helicopters with MOD 074263 installed. EASA AD 2023-0187R1 also specifies procedures for repetitively inspecting for no marks, residue, or corrosion and testing the "IDLE" and "FLIGHT" controls on the pilot's and copilot's twist grips on helicopters with MOD 074699 installed. Additionally, EASA AD 2023-0187R1 specifies procedures for installing MOD 074782 on helicopters if an affected microswitch is installed, which would constitute terminating action for the repetitive inspections. For those helicopters with MOD 074782 installed, EASA AD 2023-0187R1 specifies accomplishing a one-time inspection of the installation of the microswitch assembly of the engine power control. EASA AD 2023-0187R1 also prohibits installing a microswitch having a part number (P/N) T3933-3 or a twist grip containing a microswitch having P/N T3933-3 on any helicopter. 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. Differences Between This AD and the MCAI The MCAI specifies the initial inspections within 10 flight hours or 7 days; this AD requires compliance before the next autorotation training flight, 100 hours time-in-service, or 6 months, whichever occurs first, as the unsafe condition only occurs when transitioning the throttle in-flight from flight to idle and back to flight, such as during a practice autorotation. Additionally, the MCAI specifies installing Airbus Helicopters MOD 074263; this AD does not require that modification as it would not correct the unsafe condition. Costs of Compliance The FAA estimates that this AD affects 856 helicopters of U.S. registry. Labor costs are estimated at $85 per hour. Based on these numbers, the FAA estimates the following costs to comply with this AD. Inspecting the wiring, performing an insulation test, inspecting the pilot and copilot twist grip controls, and testing the pilot and copilot twist grip controls required by MOD 074699 takes about 4 work-hours, for an estimated cost of $340 per helicopter and $291,040 for the U.S. fleet. Installing MOD 074782 takes about 4 work-hours, for an estimated cost of $340 per helicopter. The FAA has included all known costs in its cost estimate. According to the manufacturer, however, some 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 The FAA has determined that 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 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: a. Removing Airworthiness Directive 2020-24-07, Amendment 39-21337 (85 FR 78954, December 8, 2020); and b. Adding the following new airworthiness directive: 2025-18-13 Airbus Helicopters: Amendment 39-23140; Docket No. FAA-2025-1108; Project Identifier MCAI-2025-00428-R. (a) Effective Date This airworthiness directive (AD) is effective October 23, 2025. (b) Affected ADs This AD replaces AD 2020-24-07, Amendment 39-21337 (85 FR 78954, December 8, 2020) (AD 2020-24-07). (c) Applicability This AD applies to Airbus Helicopters Model AS350B3, EC130B4, and EC130T2 helicopters, certificated in any category. (d) Subject Joint Aircraft System Component (JASC) Code 7600, Engine Controls. (e) Unsafe Condition This AD was prompted by reports of the of the engine remaining in idle when the throttle twist grip was turned from the "IDLE" mode to the "FLIGHT" mode. The FAA is issuing this AD to correct the failure of one of the microswitches, 53Ka, 53Kb, or 65K which can prevent the pilot from switching from "IDLE" mode to "FLIGHT" mode during autorotation training making it impossible to recover from a practice autorotation and compelling the pilot to continue the autorotation to the ground. This condition could result in unintended touchdown to the ground at a flight-idle power setting during a practice autorotation, damage to the helicopter, and injury to occupants. (f) Compliance Comply with this AD within the compliance times specified, unless already done. (g) Requirements Except as specified in paragraph (h) of this AD: Comply with all required actions and compliance times specified in, and in accordance with, European Union Aviation Safety Agency AD 2023-0187R1, dated March 20, 2025 (EASA AD 2023-0187R1). (h) Exceptions to EASA AD 2023-0187R1 (1) Where EASA AD 2023-0187R1 refers to the effective dates identified in paragraphs (h)(1)(i) through (iii) of this AD, this AD requires using the effective date of this AD. (i) March 27, 2025 (the effective date of EASA AD 2023-0187R1). (ii) November 10, 2023 (the effective date of EASA AD 2023-0187, dated October 27, 2023). (iii) July 19, 2023 (the effective date of EASA AD 2023-0133, dated July 5, 2023). (2) Where EASA AD 2023-0187R1 refers to April 13, 2017 (the effective date of EASA AD 2017-0059, dated April 6, 2017), this AD requires using January 30, 2019 (the effective date of AD 2018-26-02, Amendment 39-19532 (83 FR 66093, December 26, 2018)). (3) Where EASA AD 2023-0187R1 refers to flight hours (FH), this AD requires using hours time-in-service. (4) This AD does not adopt paragraphs (1) and (2) of EASA AD 2023-0187R1. (5) Instead of complying with the compliance times in Table 1 in paragraph (3) of EASA AD 2023-0187R1, this AD requires the helicopters identified under the Helicopters in Pre-MOD 074699 Configuration column to accomplish the actions required by paragraph (3) of EASA AD 2023-0187R1 before the next practice autorotation, within 100 hours time-in-service, or 6 months after January 12, 2021 (the effective date of AD 2020-24-07), whichever occurs first. (6) Where Table 2 in paragraph (4), Table 3 in paragraph (7), and Table 4 in paragraph (9) of EASA AD 2023-0187R1 state "For helicopters which operate or have operated in salt-laden atmospheric conditions", this AD requires replacing that text with "For helicopters which operate or have operated in salt-laden atmospheric conditions, or if it cannot be determined if a helicopter has been operated in salt-laden atmospheric conditions". (7) Where paragraph (6) of EASA AD 2023-0187R1 states "discrepancies are detected", this AD requires replacing that text with "marks, residue, corrosion, flaky varnish are detected; the values of the insulation test are less than 10 megaOhms; the microswitch closes in the "IDLE" position and does not open as soon as the twist grip is turned to the "FLIGHT" position; or the microswitch is open in the "FLIGHT" position and does not close as soon as the twist grip is turned to the "IDLE" position". (8) Where paragraph (9) of EASA AD 2023-0187R1 states "any discrepancy," for purposes of this AD, discrepancy is defined as a nut torque that is outside allowable torque limits, or clearance between the support plate assembly and the washers that is not within 01.mm to 0.3 mm. (9) This AD does not adopt the "Remarks" section of EASA AD 2023-0187R1. (i) 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 (j) of this AD and email to: AMOC@faa.gov . (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. (j) Additional Information For more information about this AD, contact Zain Jamal, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; phone: (847) 294-7264; email: zain.jamal@faa.gov . (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 the AD specifies otherwise. (i) European Union Aviation Safety Agency (EASA) AD 2023-0187R1, dated March 20, 2025. (ii) [Reserved] (3) For EASA material identified in this AD, contact EASA, Konrad-Adenauer-Ufer 3, 50668 Cologne, Germany; phone: +49 221 8999 000; email: ADs@easa.europa.eu; website: easa.europa.eu . You may find this EASA material on the EASA website at ad.easa.europa.eu. (4) You may view this material at FAA, Office of the Regional Counsel, Southwest Region, 10101 Hillwood Parkway, Room 6N-321, Fort Worth, TX 76177. 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 fr.inspection@nara.gov . Issued on September 9, 2025. Steven W. Thompson, Acting Deputy Director, Compliance & Airworthiness Division, Aircraft Certification Service.