SUPPLEMENTARY INFORMATION:

Comments Invited

The FAA invites you to send any written relevant data, views, or arguments about this proposal. Send your comments using a method listed under the ADDRESSES section. Include “Docket No. FAA-2026-3878; Project Identifier MCAI-2025-00913-T” at the beginning of your comments. The most helpful comments reference a specific portion of the proposal, 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 proposal 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 NPRM.

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 NPRM 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 NPRM, 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 NPRM. Submissions containing CBI should be sent to Christopher Spencer, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; phone: 516-228-7332; email: 9-AVS-AIR-BACO-COS@faa.gov. 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 FAA issued AD 2023-21-10, Amendment 39-22582 (88 FR 83820, December 1, 2023) (AD 2023-21-10), for certain ATR—GIE Avions de Transport Régional Model ATR42-500 and ATR72-212A airplanes. AD 2023-21-10 was prompted by an MCAI originated by EASA, which is the Technical Agent for the Member States of the European Union. EASA issued AD 2023-0125, ( printed page 23920) dated June 22, 2023, to correct an unsafe condition.

AD 2023-21-10 requires an inspection of the HS affected areas (HS left-hand and right-hand leading edge lateral ribs, the box in between, the center box upper panel, and HS forward back-up fitting) for discrepancies and applicable corrective action. The FAA issued AD 2023-21-10 to address loose, missing, or incorrectly installed fasteners, composite delamination, and cracks in the HS. The unsafe condition, if not addressed, could result in reduced structural integrity of the airplane.

Actions Since AD 2023-21-10 Was Issued

Since the FAA issued AD 2023-21-10, EASA superseded AD 2023-0125, dated June 22, 2023, and issued EASA AD 2025-0110, dated May 14, 2025 (EASA AD 2025-0110) (also referred to as the MCAI), to correct an unsafe condition for certain ATR—GIE Avions de Transport Régional Model ATR42-500 and ATR72-212A airplanes. The MCAI states that it has been determined that additional airplane serial numbers are affected and that the HS front spar web and center box internal area also needs to be inspected to address loose, missing, or incorrectly installed fasteners, composite delamination, and cracks in the HS.

The FAA is proposing this AD to address the unsafe condition on these products. You may examine the MCAI in the AD docket at regulations.gov under Docket No. FAA-2026-3878.

Explanation of Retained Requirements

Although this proposed AD does not explicitly restate the requirements of AD 2023-21-10, this proposed AD would retain all of the requirements of AD 2023-21-10. Those requirements are referenced in EASA AD 2025-0110, which, in turn, is referenced in paragraph (g) of this proposed AD.

Material Incorporated by Reference Under 1 CFR Part 51

The FAA reviewed EASA AD 2025-0110, which specifies procedures for a one-time detailed inspection of the HS left-hand and right-hand leading edge lateral ribs, the box in between the center box upper panel, HS forward back-up fitting, and the HS front spar web and center box internal area for discrepancies ( i.e., any loose, missing, or incorrectly installed fasteners, any composite delamination, and any cracked fittings); and applicable corrective action. Corrective actions include contacting the manufacturer for repair instructions if any discrepancy is detected during any inspection.

The FAA also reviewed ATR Service Bulletin ATR42-55-0020, Revision 03, dated January 31, 2025; ATR Service Bulletin ATR72-55-1013, Revision 03, dated January 31, 2025; ATR Service Bulletin ATR42-55-0025, dated February 3, 2025; and ATR Service Bulletin ATR72-55-1018, dated February 3, 2025. This material identifies the affected airplane serial numbers.

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 NPRM after determining that the unsafe condition described previously is likely to exist or develop in other products of the same type design.

Proposed AD Requirements in This NPRM

This proposed AD would require accomplishing the actions specified in EASA AD 2025-0110 described previously, except for any differences identified as exceptions in the regulatory text of this proposed AD.

Explanation of Required Compliance Information

In the FAA's ongoing efforts to improve the efficiency of the AD process, the FAA developed a process to use some civil aviation authority (CAA) ADs as the primary source of information for compliance with requirements for corresponding FAA ADs. The FAA has been coordinating this process with manufacturers and CAAs. As a result, the FAA proposes to incorporate EASA AD 2025-0110 by reference in the FAA final rule. This proposed AD would, therefore, require compliance with EASA AD 2025-0110 in its entirety through that incorporation, except for any differences identified as exceptions in the regulatory text of this proposed AD. Using common terms that are the same as the heading of a particular section in EASA AD 2025-0110 does not mean that operators need comply only with that section. For example, where the AD requirement refers to “all required actions and compliance times,” compliance with this AD requirement is not limited to the section titled “Required Action(s) and Compliance Time(s)” in EASA AD 2025-0110. Material required by EASA AD 2025-0110 for compliance will be available at regulations.gov under Docket No. FAA-2026-3878 after the FAA final rule is published.

Costs of Compliance

The FAA estimates that this AD, if adopted as proposed, would affect 16 airplanes of U.S. registry. The FAA estimates the following costs to comply with this proposed AD:

The FAA has received no definitive data on which to base the cost estimates for the on-condition repairs specified in this proposed AD.

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 ( printed page 23921) 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 determined that this proposed AD would not have federalism implications under Executive Order 13132. This proposed AD would 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 this proposed regulation:

(1) Is not a “significant regulatory action” under Executive Order 12866,

(2) Would not affect intrastate aviation in Alaska, and

(3) Would not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act.

The Proposed Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 14 CFR part 39 as follows:

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 (AD) 2023-21-10, Amendment 39-22582 ( 88 FR 83820, December 1, 2023); and

b. Adding the following new AD:

ATR—GIE Avions de Transport Régional: Docket No. FAA-2026-3878; Project Identifier MCAI-2025-00913-T.

(a) Comments Due Date

The FAA must receive comments on this airworthiness directive (AD) by June 18, 2026.

(b) Affected ADs

This AD replaces AD 2023-21-10, Amendment 39-22582 (88 FR 83820, December 1, 2023) (AD 2023-21-10).

(c) Applicability

This AD applies to ATR—GIE Avions de Transport Régional Model ATR42-500 and ATR72-212A airplanes, certificated in any category, as identified in ATR Service Bulletin ATR42-55-0020, Revision 03, dated January 31, 2025; ATR Service Bulletin ATR72-55-1013, Revision 03, dated January 31, 2025; ATR Service Bulletin ATR42-55-0025, dated February 3, 2025; or ATR Service Bulletin ATR72-55-1018, dated February 3, 2025; as applicable.

(d) Subject

Air Transport Association (ATA) of America Code 55, Stabilizers.

(e) Unsafe Condition

This AD was prompted by reports of loose fasteners and cracks in the horizontal stabilizer (HS) left- and right-hand leading edge lateral ribs, the box in between, the center box upper panel, and HS forward back-up fitting. This AD was also prompted by a determination that additional airplanes are affected by the unsafe condition, and that the HS front spar web and center box internal area also need to be inspected. The FAA is issuing this AD to address loose, missing, or incorrectly installed fasteners, composite delamination, and cracks in the HS. The unsafe condition, if not addressed, could result in reduced structural integrity of the airplane.

(f) Compliance

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

(g) Requirements

Except as specified in paragraphs (h) and (i) of this AD: Comply with all required actions and compliance times specified in, and in accordance with, European Union Aviation Safety Agency (EASA) AD 2025-0110, dated May 14, 2025 (EASA AD 2025-0110).

(h) Exceptions to EASA AD 2025-0110

(1) Where the Groups definition for Group 3 airplanes in EASA AD 2025-0110 refers to “the SB2”, this AD requires replacing this text with “ATR Service Bulletin ATR42-55-0025, dated February 3, 2025; or ATR Service Bulletin ATR72-55-1018, dated February 3, 2025; as applicable”.

(2) Where EASA AD 2025-0110 refers to “06 July 2023 [the effective date of EASA AD 2023-0125],” this AD requires using January 5, 2024 (the effective date of AD 2023-21-10).

(3) Where EASA AD 2025-0110 refers to its effective date, this AD requires using the effective date of this AD.

(4) Where paragraph (2) of EASA AD 2025-0110 specifies if “any discrepancy as defined in the SB1 or the SB2, as applicable, is detected, before next flight, contact ATR for approved repair instructions and, within the compliance time identified therein, accomplish those instructions accordingly. If no compliance time for the repair is identified in those instructions, accomplish those instructions before next flight.”, this AD requires replacing that text with “any discrepancy other than cracking is detected, before next flight, contact ATR for approved repair instructions and, within the compliance time identified therein, accomplish those instructions accordingly, except if no compliance time for the repair is identified in those instructions, accomplish those instructions before next flight; and if any crack is detected, the crack must be repaired before further flight using a method approved by the Manager, International Validation Branch, FAA; or EASA; or ATR—GIE Avions de Transport Régional's EASA Design Organization Approval (DOA). If approved by the DOA, the approval must include the DOA-authorized signature.”

(5) This AD does not adopt the “Remarks” section of EASA AD 2025-0110.

(i) No Reporting Requirement

Although the material referenced in EASA AD 2025-0110 specifies to submit certain information to the manufacturer, this AD does not include that requirement.

(j) Additional AD Provisions

The following provisions also apply to this AD:

(1) Alternative Methods of Compliance (AMOCs): 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 responsible Flight Standards 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 (k) of this AD and email to: AMOC@faa.gov. Before using any approved AMOC, notify your appropriate principal inspector, or lacking a principal inspector, the manager of the responsible Flight Standards Office.

(2) Contacting the Manufacturer: For any requirement in this AD to obtain instructions from a manufacturer, the instructions must be accomplished using a method approved by the Manager, International Validation Branch, FAA; or EASA; or ATR—GIE Avions de Transport Régional's EASA Design Organization Approval (DOA). If approved by the DOA, the approval must include the DOA-authorized signature.

(k) Additional Information

For more information about this AD, contact Christopher Spencer, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; phone: 516-228-7332; email: 9-AVS-AIR-BACO-COS@faa.gov.

(l) 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 this AD specifies otherwise. ( printed page 23922)

(i) ATR Service Bulletin ATR42-55-0020, Revision 03, dated January 31, 2025.

(ii) ATR Service Bulletin ATR42-55-0025, dated February 3, 2025.

(iii) ATR Service Bulletin ATR72-55-1013, Revision 03, dated January 31, 2025.

(iv) ATR Service Bulletin ATR72-55-1018, dated February 3, 2025.

(v) European Union Aviation Safety Agency (EASA) AD 2025-0110, dated May 14, 2025.

(3) For EASA material identified in this AD, contact EASA, Konrad-Adenauer-Ufer 3, 50668 Cologne, Germany; telephone +49 221 8999 000; email ADs@easa.europa.eu. You may find this material on the EASA website at ad.easa.europa.eu.

(4) For ATR—GIE Avions de Transport Régional material identified in this AD, contact ATR—GIE Avions de Transport Régional, 1 Allée Pierre Nadot, 31712 Blagnac Cedex, France; telephone +33 (0) 5 62 21 62 21; fax +33 (0) 5 62 21 67 18; email continued.airworthiness@atr aircraft.com; website atr-aircraft.com.

(5) You may view this material at the FAA, Airworthiness Products Section, Operational Safety Branch, 2200 South 216th St., Des Moines, WA. For information on the availability of this material at the FAA, call 206-231-3195.

(6) 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.

91 FR 23919