2025-23-07: Main Rotor Transmission Mount

1. The authority citation for part 39 continues to read as follows: Authority: 49 U.S.C. 106(g), 40113, 44701. 2. The FAA amends § 39.13 by: a. Removing Airworthiness Directive 2020-06-12, Amendment 39-19881 (85 FR 19077, April 6, 2020); and b. Adding the following new airworthiness directive: 2025-23-07 Airbus Helicopters: Amendment 39-23190; Docket No. FAA-2025-1736; Project Identifier MCAI-2024-00435-R. (a) Effective Date This airworthiness directive (AD) is effective January 12, 2026. (b) Affected ADs This AD replaces AD 2020-06-12, Amendment 39-19881 (85 FR 19077, April 6, 2020). (c) Applicability This AD applies to Airbus Helicopters, certificated in any category, identified in paragraphs (c)(1) and (2) of this AD. (1) Model AS 332L2 helicopters with a main gearbox (MGB) suspension bar front attachment bolt part number (P/N) 332A22-1613-20 or 332A22-1613-21, MGB suspension bar rear attachment bolt P/N 332A22-1614-20, MGB suspension bar front attachment fitting P/N 332A22-1623-01, MGB suspension bar rear left-hand attachment fitting P/N 332A22-1624-02 or 332A22-1624-04, or MGB suspension bar rear right-hand attachment fitting P/N 332A22-1624-03 or 332A22-1624-05 installed. (2) Model EC 225LP helicopters with MGB suspension bar front attachment bolt P/N 332A22-1613-21 or MGB suspension bar rear attachment bolt P/N 332A22-1614-20 installed. Note 1 to paragraph (c): Airbus Helicopters refers to MGB suspension bar attachment bolts as "pins." (d) Subject Joint Aircraft System Component (JASC) Code 6330, Main Rotor Transmission Mount. (e) Unsafe Condition This AD was prompted by a report of torque loss on a MGB suspension bar attachment bolt (bolt). The FAA is issuing this AD to prevent MGB suspension bar attachment fittings (fitting) and bolts remaining in service beyond their fatigue life. The unsafe condition, if not addressed, could result in structural failure of an MGB attachment assembly, detachment of an MGB suspension bar, and consequent loss of control of the helicopter. (f) Compliance Comply with this AD within the compliance times specified, unless already done. (g) Required Actions for Bolts For helicopters identified in paragraphs (c)(1) and (2) of this AD without Airbus Helicopters modifications 0728521, 0728904, 0728496, and 0729044 installed, within 30 hours time-in-service (TIS) after the effective date of this AD, review records to determine the total hours TIS of each bolt. (1) Determine the life limit of each bolt by applying its total hours TIS by the add-on factor listed in Table No. 1 of Airbus Helicopters Emergency Alert Service Bulletin (EASB) No. 01.00.86, Revision 4, dated January 6, 2022 (EASB 01.00.86 Rev 4), or Airbus Helicopters EASB No. 04A013, Revision 4, dated January 6, 2022, as applicable to your model helicopter. (i) Before further flight, remove from service any bolt that has reached or exceeded its life limit, and remove its associated MGB suspension bar attachment nut (nut) and cotter pins from service. Remove the associated convex and concave washers. Thereafter, before each flight, continue to calculate and record the life limit of each bolt on its component history card or equivalent record by applying the add-on factor each time the helicopter accumulates hours TIS and remove from service any bolt before reaching its life limit, along with its associated nut and cotter pins. Remove its associated convex and concave washers. (ii) For each bolt that has not exceeded its life limit, before each flight, continue to calculate and record the life limit on its component history card or equivalent record by applying the add-on factor each time the helicopter accumulates hours TIS and remove from service any bolt before reaching its life limit, along with its associated nut and cotter pins. Remove the associated convex and concave washers. (2) Before further flight, if any nut, bolt, or cotter pin was removed from service as a result of the actions in paragraph (g)(1) of this AD, replace those parts with airworthy parts, and install new (never installed) convex and concave washers or reinstall the convex and concave washers that were removed (if washers are airworthy). Torque each newly-installed nut to the minimum allowable torque value of: 735-840 lbf. in (8.3 daN.m to 9.5 daN.m) on the front nuts of the fittings, and 496-566 lbf. in (5.6 daN.m to 6.4 daN.m) on the rear nuts of the fittings. (h) Required Actions for Fittings For helicopters identified in paragraph (c)(1) of this AD without Airbus Helicopters modification 0728521, 0728904, 0728496, and 0729044 installed, within 30 hours TIS after the effective date of this AD, review records to determine the total hours TIS of each fitting. (1) Determine the life limit of each fitting by applying its total hours TIS by the add-on factor listed in Table No. 1 of EASB 01.00.86 Rev 4. (i) Before further flight, remove from service any fitting that has reached or exceeded its life limit, and remove its associated nuts, and cotter pins from service. Remove its associated convex and concave washers and bolts. Thereafter, before each flight, continue to calculate and record the life limit of each fitting on its component history card or equivalent record by applying the add-on factor each time the helicopter accumulates hours TIS and remove from service any fitting before reaching its life limit, along with its associated, nuts, and cotter pins. Remove its associated convex and concave washers and bolt. (ii) For each fitting that has not exceeded its life limit, before each flight, continue to calculate and record the life limit of each fitting on its component history card or equivalent record by applying the add-on factor each time the helicopter accumulates hours TIS and remove from service any fitting before reaching its life limit, along with its associated, nuts and cotter pins from service. Remove its associated bolts, convex and concave washers. (2) Before further flight, if any fitting or its associated nut, or cotter pin was removed from service as a result of the actions in paragraph (h)(1) of this AD, replace those parts with airworthy parts, and install new (never installed) convex and concave washers and bolt or reinstall the convex and concave washers and bolt that were removed (if the washers and bolt are airworthy). Torque each newly-installed nut using the allowable torque value in paragraph (g)(2) of this AD. (i) Required Actions for Torque Values For helicopters identified in paragraph (c)(1) of this AD without Airbus Helicopters modification 0728521, 0728904, 0728496, and 0729044 installed, within 150 hours TIS (without the add-on factor) after the effective date of this AD, inspect the torque of each nut. (1) If the torque on any nut is higher than the maximum allowable torque stated in paragraph (g)(2) of this AD, before further flight, remove the nut, its associated bolt, and its cotter pins from service. (2) If the torque on any nut is lower than the minimum allowable torque value stated in paragraph (g)(2) of this AD, before further flight, tighten the nut to the allowable torque stated in paragraph (g)(2) of this AD. (3) Within 150 hours TIS (without the add-on factor), remove from service any nut its associated bolt, and its cotter pins that were tightened as required by paragraph (i)(2) of this AD, and torque each newly-installed nut using the allowable torque value in paragraph (g)(2) of this AD. (j) Required Actions for Links (1) For helicopters identified in paragraph (c)(1) of this AD without Airbus Helicopters modification 0728521, 0728904, 0728496, and 0729044 installed, within 825 hours TIS or 27 months after the effective date of this AD, whichever occurs first, modify the helicopter by installing attachment bracket links for the MGB suspension bars in accordance with the Accomplishment Instructions, paragraphs 3.B.2.a through 3.B.3.i., of Airbus Helicopters Alert Service Bulletin (ASB) No. AS332-53.02.03, Revision 2, dated June 15, 2023 (ASB AS332-53.02.03 Rev 2), except as provided in paragraphs (j)(1)(i) through (ix) of this AD. Note 2 to the introductory text of paragraph (j)(1): Airbus refers to the installation of the attachment bracket links for the MGB suspension bar as modification 0728496, 0728521, 0728904, and 0729044. (i) Instead of discarding parts, you must remove those parts from service. (ii) Where ASB AS332-53.02.03 Rev 2 uses the term check, this AD requires doing an inspection. (iii) You are not required to define or record the thickness of the peel shims. (iv) Instead of contacting Airbus Helicopters if there is damage after removing corrosion, this AD requires that you remove the affected part from service before further flight. (v) Instead of contacting Airbus Helicopters if there are any cracks on the frames at the attachment bracket fixations, this AD requires that you remove the affected part from service before further flight. (vi) For purposes of this AD, "correctly stacked" as used in ASB AS332-53.02.03 Rev 2 means the concave washers are installed with the flat side towards the front bracket, and the convex washers are installed with the flat side towards the nuts. (vii) For purposes of this AD, "correctly engaged" as used in ASB AS332-53.02.03 Rev 2 means the centering pin is engaged on the front plate. (viii) Instead of contacting Airbus Helicopters if the clearance of J1 or J2 is less than 0.5 mm (0.0196 in) after inspecting the new links of the rear brackets, you must take corrective action until the clearance is at least 0.5 mm using a method approved by the Manager, General Aviation & Rotorcraft Section, International Validation Branch, FAA; or European Union Aviation Safety Agency (EASA); or Airbus Helicopters EASA Design Organization Approval (DOA). If approved by the DOA, the approval must include the DOA-authorized signature. (ix) For the purposes of this AD, new as used in ASB AS332-53.02.03 Rev 2 means the part has never been installed on a helicopter. (2) For helicopters identified in paragraph (c)(2) of this AD without Airbus Helicopters modification 0728521, 0728904, 0728496, and 0729044 installed, within 1,320 hours TIS or 40 months after the effective date of this AD, whichever occurs first, modify the helicopter by installing bracket links for the MGB suspension bars in accordance with the Accomplishment Instructions, paragraphs 3.B.2. through 3.B.3.i, of Airbus Helicopters ASB No. EC225-53A065, Revision 4, dated May 28, 2024 (ASB EC225-53A065 Rev 4), except as provided in paragraphs (j)(2)(i) through (ix) of this AD. (i) Instead of discarding parts, you must remove those parts from service. (ii) Where ASB EC225-53A065 Rev 4 uses the term check, this AD requires doing an inspection. (iii) You are not required to define or record the thickness of the peel shims. (iv) Instead of contacting Airbus Helicopters if there is damage after removing corrosion, this AD requires that you remove the affected part from service before further flight. (v) Instead of contacting Airbus Helicopters if there are any cracks on the frames at the attachment bracket fixations, this AD requires that you remove the affected part from service before further flight. (vi) For the purposes of this AD, "correctly stacked" as used in ASB EC225-53A065 Rev 4 means the concave washers are installed with the flat side towards the bracket, and the convex washers are installed with the flat side towards the nuts. (vii) For purposes of this AD, "correctly engaged" as used in ASB EC225-53A065 Rev 4 means the centering pin is engaged on the front plate. (viii) Instead of contacting Airbus Helicopters if the clearance of J1 or J2 is less than 0.5 mm (0.0196 in) after inspecting the new links of the rear brackets, you must take corrective action until the clearance is at least 0.5 mm using a method approved by the Manager, General Aviation & Rotorcraft Section, International Validation Branch, FAA; or EASA; or Airbus Helicopters EASA Design Organization Approval (DOA). If approved by the DOA, the approval must include the DOA-authorized signature. (ix) Where ASB EC225-53A065 Rev 4 uses the phrase "if necessary", this AD requires replacing that text with "if applicable". (3) For helicopters identified in paragraphs (c)(1) and (2) of this AD that have Airbus Helicopter modification 0728521, 0728904, 0728496, and 0729044 installed before the effective date of this AD, within 27 months for Model AS 332L2 helicopters, and within 40 months for Model EC 225LP helicopters, after the effective date of this AD, modify the helicopter in accordance with the Accomplishment Instructions, paragraphs 3.B.2.c.1.b through 3.B.2.c.2.b of ASB AS332-53.02.03 Rev 2 or ASB EC225-53A065 Rev 4, as applicable to your model helicopter, and tighten to the standard torque value, except instead of discarding parts, you must remove those parts from service. (4) Modifying the helicopter as required by paragraphs (j)(1) or (2) of this AD terminates the life limit required by paragraphs (g) and (h) of this AD. (k) Installation Prohibition As of the effective date of this AD, do not install front bolt P/N 332A22-1613-20 or 332A22-1613-21, rear bolt P/N 332A22-1614-20, front fitting P/N 332A22-1623-01, rear left-hand fitting P/N 332A22-1624-02 or 332A22-1624-04, or rear right-hand fitting P/N 332A22-1624-03 or 332A22-1624-05 on any helicopter, unless: (1) The part has not exceeded the applicable service life limit after accomplishing the actions required by paragraphs (g)(1) or (h)(1) of this AD, as applicable; and (2) After installation of the part, the life limit is calculated in accordance with paragraph (g)(1) or (h)(1) of this AD and all other applicable requirements of this AD are accomplished. (l) Credit for Previous Actions (1) For Model AS 332L2 helicopters, paragraph (l)(1) of this AD provides credit for the initial life limit calculations required by paragraphs (g)(1) and (h)(1) of this AD, if those calculations were performed before the effective date of this AD using the material identified in paragraphs (l)(1)(i) through (iv) of this AD. (i) Airbus Helicopters EASB No. 01.00.86, Revision 0, dated July 27, 2017. (ii) Airbus Helicopters EASB No. 01.00.86, Revision 1, dated August 25, 2017. (iii) Airbus Helicopters EASB No. 01.00.86, Revision 2, dated March 2, 2020. (iv) Airbus Helicopters EASB No. 01.00.86, Revision 3, dated August 19, 2021. (2) For Model EC 225LP helicopters, paragraph (l)(2) of this AD provides credit for the initial life limit calculations required by paragraph (g)(1) of this AD, if those calculations were performed before the effective date of this AD using the material identified in paragraphs (l)(2)(i) through (iv) of this AD. (i) Airbus Helicopters EASB No. 04A013, Revision 0, dated July 27, 2017. (ii) Airbus Helicopters EASB No. 04A013, Revision 1, dated August 25, 2017. (iii) Airbus Helicopters EASB No. 04A013, Revision 2, dated March 2, 2020. (iv) Airbus Helicopters EASB No. 04A013, Revision 3, dated August 19, 2021. (m) 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 (n)(1) of this AD. Information may be emailed 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. (n) Additional Information (1) For more information about this AD, contact Dan McCully, Aviation Safety Engineer, FAA, 1600 Stewart Avenue Suite 410, Westbury, NY 11590; phone: (781) 238-7244; email: william.mccully@faa.gov. (2) Material identified in this AD that is not incorporated by reference is available at the address specified in paragraph (o)(3) of this AD. (o) 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) Airbus Helicopters Alert Service Bulletin No. AS332-53.02.03, Revision 2, dated June 15, 2023. (ii) Airbus Helicopters Alert Service Bulletin No. EC225-53A065, Revision 4, dated May 28, 2024. (iii) Airbus Helicopters Emergency Alert Service Bulletin No. 01.00.86, Revision 4, dated January 6, 2022. (iv) Airbus Helicopters Emergency Alert Service Bulletin No. 04A013, Revision 4, dated January 6, 2022. (3) 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: airbus.com/en/products-services/helicopters/hcare-services/airbusworld. (4) 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. (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 December 2, 2025. Steven W. Thompson, Acting Deputy Director, Compliance & Airworthiness Division, Aircraft Certification Service. [FR Doc. 2025-22218 Filed 12-5-25; 8:45 am]BILLING CODE 4910-13-P