Airworthiness Directives; Airbus Helicopters

<RULE> DEPARTMENT OF TRANSPORTATION <SUBAGY>Federal Aviation Administration</SUBAGY> <CFR>14 CFR Part 39</CFR> <DEPDOC>[Docket No. FAA-2025-0922; Project Identifier MCAI-2024-00650-R; Amendment 39-23163; AD 2025-20-10]</DEPDOC> <RIN>RIN 2120-AA64</RIN> <SUBJECT>Airworthiness Directives; Airbus Helicopters</SUBJECT> <HD SOURCE="HED">AGENCY:</HD> Federal Aviation Administration (FAA), DOT. <HD SOURCE="HED">ACTION:</HD> Final rule. <SUM> <HD SOURCE="HED">SUMMARY:</HD> The FAA is superseding Airworthiness Directive (AD) 2021-26-07, which applies to all Airbus Helicopters Model EC120B helicopters. AD 2021-26-07 requires performing repetitive inspections of the tail rotor (TR) hub body and, depending on the inspection results, replacing certain parts, and accomplishing further inspections. AD 2021-26-07 also requires for certain helicopters removing from service any bolt, washer, and nut installed on the TR hub body at certain life limits and replacing them with airworthy parts and accomplishing further inspections. Additionally, AD 2021-26-07 prohibits the installation of a certain part-numbered TR hub body unless certain requirements are met. Since the FAA issued AD 2021-26-07, it was determined that modifying the link of the TR hub body and splined flange by adding red paint marks is necessary to enable the detection of any loss of tightening torque. This AD retains the same repetitive inspections and corrective actions as AD 2021-26-07 and requires modification of the link of the TR hub body, which is a terminating action for the repetitive inspections. This AD also requires repetitive inspections of the red paint line added during the modification of the link of the TR hub body for alignment. The FAA is issuing this AD to address the unsafe condition on these products. </SUM> <EFFDATE> <HD SOURCE="HED">DATES:</HD> This AD is effective December 30, 2025. The Director of the Federal Register approved the incorporation by reference of certain publications listed in this AD as of December 30, 2025. </EFFDATE> <HD SOURCE="HED">ADDRESSES:</HD> <E T="03">AD Docket:</E> You may examine the AD docket at <E T="03">regulations.gov</E> under Docket No. FAA-2025-0922; 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. <E T="03">Material Incorporated by Reference:</E> • For Airbus Helicopters material identified in this AD, contact Airbus Helicopters, 2701 North Forum Drive, Grand Prairie, TX 75052; phone: (972) 641-0000 or: (800) 232-0323; fax: (972) 641-3775; website: <E T="03">airbus.com/en/products-services/helicopters/hcare-services/airbusworld.</E> • You may view this material at the 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. It is also available at <E T="03">regulations.gov</E> under Docket No. FAA-2025-0922. <FURINF> <HD SOURCE="HED">FOR FURTHER INFORMATION CONTACT:</HD> Camille Seay, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; phone: (817) 222-5149; email: <E T="03">camille.l.seay@faa.gov.</E> </FURINF> <SUPLINF> <HD SOURCE="HED">SUPPLEMENTARY INFORMATION:</HD> <HD SOURCE="HD1">Background</HD> The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to supersede AD 2021-26-07, Amendment 39-21866 (86 FR 72829, December 23, 2021) (AD 2021-26-07), which applied to all Airbus Helicopters Model EC120B helicopters. The NPRM published in the <E T="04">Federal Register</E> on June 25, 2025 (90 FR 26951). The NPRM was prompted by European Union Aviation Safety Agency (EASA) AD 2024-0209, dated October 28, 2024 (EASA AD 2024-0209) (also referred to as the MCAI). EASA, the Technical Agent for the Member States of the European Union, issued EASA AD 2024-0209 to address loss of tightening torque in the interface between the TR hub body and splined flange, which creates the risk of crack initiation from a fretting area located on the TR hub body and splined flange or on the TR hub body and flange bolts. The MCAI states that Airbus Helicopters developed a modification, which consists of adding a line of red paint on each bolt and each nut of the link between the TR hub and the splined flange. The MCAI further states that an Airworthiness Limitations Section task was published for checking alignment of the marks. The FAA is issuing this AD to detect cracking and fretting of the TR hub body, which, if not addressed, could lead to loss of the TR drive, and consequent loss of yaw control of the helicopter. You may examine the MCAI in the AD docket at <E T="03">regulations.gov</E> under Docket No. FAA-2025-0922. <HD SOURCE="HD1">Discussion of Final Airworthiness Directive</HD> <HD SOURCE="HD1">Comments</HD> The FAA received no comments on the NPRM or on the determination of the costs. <HD SOURCE="HD1">Conclusion</HD> 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 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. <HD SOURCE="HD1">Material Incorporated by Reference Under 1 CFR Part 51</HD> The FAA reviewed Airbus Helicopters Emergency Alert Service Bulletin 05A020, Revision 3, dated September 19, 2024 (EASB 05A0020 Rev 3), which specifies procedures for repetitive inspections of the TR hub body for cracks and the TR spline flange for cracks and fretting and the appropriate corrective actions to include replacing the hub body and the splined flange. EASB 05A0020 Rev. 3 also excludes helicopters that have complied with Airbus Helicopters Alert Service Bulletin EC120-64-21-0001, Issue 001, dated September 19, 2024 (ASB EC120-64-21-0001) from its effectivity and limits the effectivity for “non installed equipment or parts”. The FAA also reviewed ASB EC120-64-21-0001, which specifies procedures for inspecting the torque applied on the nut of the link between the TR hub and the splined flange, and depending on the inspection results, applying torque and replacing parts. ASB EC120-64-21-0001 also specifies procedures for applying a red paint line on the screw, nut, washer, TR hub, and splined flange. 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 <E T="02">ADDRESSES</E> section. <HD SOURCE="HD1">Differences Between This AD and the MCAI</HD> EASA AD 2024-0209 allows a non-cumulative tolerance of 100 FH [flight hours] to be applied to the compliance times to allow for synchronization of the required inspections with other maintenance tasks, whereas this AD does not allow a non-cumulative tolerance to be applied to the compliance times. <HD SOURCE="HD1">Costs of Compliance</HD> The FAA estimates that this AD affects 70 helicopters of U.S. registry. Labor rates are estimated at $85 per hour. Based on these numbers, the FAA estimates the following costs to comply with this AD. Visually inspecting a TR hub body for a crack takes 0.25 work-hour for an estimated cost of $22 per helicopter and $1,540 for the U.S. fleet. Visually inspecting a TR spline flange for corrosion, impacts, fretting, wear, and a crack takes 0.25 work-hour for an estimated cost of $22 per helicopter and $1,540 for the U.S. fleet. Replacing a T/R hub body bolt, washer, and nut takes 0.5 work-hour and parts cost $25 (per hardware set) for an estimated cost of $68 per helicopter. Inspecting torque and adding a red paint line on each bolt and each nut takes 4 work-hours for an estimated cost of $340 per helicopter and $23,800 for the U.S. fleet. If required, replacing a TR hub body takes 2 work-hours, and parts cost $16,485 for an estimated cost of $16,655 per helicopter. If required, replacing a TR spline flange takes 0.5 work-hour, and parts cost $2,950 for an estimated cost of $2,993 per helicopter. <HD SOURCE="HD1">Authority for This Rulemaking</HD> 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. <HD SOURCE="HD1">Regulatory Findings</HD> 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 St ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Preview showing 10k of 20k characters. 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