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 ADDRESSES . Include “Docket No. FAA-2026-4644; Project Identifier MCAI-2024-00418-R” 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 the 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 Eric Rivera, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590. 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 2023-25-14, Amendment 39-22641 (88 FR 89568, December 28, 2023) (AD 2023-25-14), for certain Airbus Helicopters Model EC130T2 helicopters. AD 2023-25-14 was prompted by an MCAI originated by EASA, which is the Technical Agent for the Member States of the European Union. EASA issued EASA Emergency AD 2023-0190-E, dated November 2, 2023 (EASA Emergency AD 2023-0190-E) to correct an unsafe condition identified as excessive vibration level on the tail rotor drive shaft, which could result in failure of the tail rotor drive shaft and subsequent loss of yaw control of the helicopter.

AD 2023-25-14 requires repetitively checking the balancing of the tail rotor drive shaft by measuring the vibration level. Depending on the results, AD 2023-25-14 requires replacing certain parts with new parts. AD 2023-25-14 prohibits installing certain part-numbered tail rotor drive shafts on any helicopter unless its requirements are met. The FAA issued AD 2023-25-14 to address an excessive vibration level on the tail rotor drive shaft. The unsafe condition, if not addressed, could result ( printed page 30258) in failure of the tail rotor drive shaft and loss of yaw control of the helicopter.

Actions Since AD 2023-25-14 Was Issued

Since the FAA issued AD 2023-25-14, EASA superseded EASA Emergency AD 2023-0190-E and issued EASA AD 2023-0190R1, dated February 20, 2024 (EASA AD 2023-0190R1). EASA AD 2023-0190R1 states a determination was made that a used equipped splined sleeve and sliding flange may be installed provided certain conditions are met. EASA then superseded EASA AD 2023-0190R1 and issued EASA AD 2024-0144, dated July 19, 2024 (EASA AD 2024-0144) (also referred to as the MCAI). The MCAI states that since EASA AD 2023-0190R1 was issued, the manufacturer developed a modification consisting of a new rear rotor drive shaft, a new sliding flange, and a new equipped splined sleeve, and that while these parts are less susceptible to cracks, insufficient data is available to treat them as terminating action for that AD's repetitive actions. In addition, EASA AD 2024-0144 expands the list of affected part numbers to include the new modified parts.

Since the issuance of AD 2023-25-14, the FAA also received a comment from Airbus Helicopters who requested changes to the actions of AD 2023-25-14, specifically in regard to the prohibition of performing a balance correction. The comment disposition below explains and addresses this comment.

The FAA is proposing this AD to continue to address excessive vibration level on the tail rotor drive shaft. The unsafe condition, if not addressed, could result in failure of the tail rotor drive shaft and loss of yaw control of the helicopter.

You may examine the MCAI in the AD docket at regulations.gov under Docket No. FAA-2026-4644.

Comment on AD 2023-25-14

The FAA gave the public the opportunity to comment on AD 2023-25-14. The following presents the comment received on AD 2023-25-14 and the FAA's response to the comment.

Request To Require the Prohibition of Balance Correction

Airbus Helicopters requested that the FAA revise AD 2023-25-14 to keep the EASA Emergency AD 2023-0190-E and associated Airbus Helicopters EASB 05A042 Revision 1 requirement to prohibit performing a balance correction, except if it is accomplished before next flight after replacing the sliding flange and the equipped splined sleeve.

The FAA agrees. The FAA determined that the balance correction prohibition was incorrectly interpreted to refer to the accomplishment of a future action or maintenance task which is not an FAA enforceable action. This proposed AD includes the prohibition.

Material Incorporated by Reference Under 1 CFR Part 51

The FAA reviewed EASA AD 2024-0144, which specifies procedures for repetitively checking the balancing of the tail rotor drive shaft by measuring the vibration level and, depending on the results, replacing certain parts with either used, new, or modified parts. EASA AD 2024-0144 also prohibits performing a balance correction unless this action is performed concurrently with replacing certain parts. If a balance correction has already been performed independently of replacing those parts, EASA AD 2024-0144 specifies contacting Airbus Helicopters to obtain approved instructions and accomplishing those instructions. EASA AD 2024-0144 also specifies reporting the vibration measurements to Airbus Helicopters and installing modified rear drive shaft, sliding flange, and equipped splined sleeve parts. Lastly, EASA AD 2024-0144 prohibits installing certain part-numbered tail rotor drive shafts, sliding flanges, or equipped splined sleeves 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.

FAA's Determination

These products have been approved by the civil aviation authority (CAA) 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 is issuing this NPRM after determining that the unsafe condition described previously is likely to exist or develop on other products of the same type design.

Proposed AD Requirements in This NPRM

This proposed AD requires accomplishing the actions specified in EASA AD 2024-0144, described previously, as incorporated by reference, except for any differences identified as exceptions in the regulatory text of this AD. See “Differences Between this Proposed AD and the MCAI” for a discussion of the general differences included in this proposed AD.

Differences Between This Proposed AD and the MCAI

For helicopters that accomplished a balance correction in accordance with the instructions of the applicable aircraft maintenance manual (AMM) before the effective date of EASA AD 2024-0144, except if this balance correction was accomplished before next flight after replacing the sliding flange and the equipped splined sleeve, EASA AD 2024-0144 requires contacting AH [Airbus Helicopters] to obtain approved instructions, and within the compliance time(s) specified therein, accomplishing those instructions accordingly. Whereas, for helicopters that accomplished a balance correction in accordance with the instructions of the applicable AMM before the effective date of this proposed AD, except those that accomplished a balance correction before the next flight after installing a new (zero total hours time-in-service) sliding flange and a new (zero total hours time-in-service) equipped splined sleeve, this proposed AD requires corrective action accomplished in accordance with a method approved by the FAA, EASA, or Airbus Helicopters' EASA Design Organization Approval.

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 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 2024-0144 by reference in the FAA final rule. This proposed AD would, therefore, require compliance with EASA AD 2024-0144 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 2024-0144 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 2024-0144. Material required by EASA AD 2024-0144 for compliance will be available at ( printed page 30259) regulations.gov under Docket FAA-2026-4644 after the FAA final rule is published.

Interim Action

The FAA considers that this proposed AD would be an interim action. If final action is later identified, the FAA might consider further rulemaking then.

Costs of Compliance

The FAA estimates that this AD, if adopted as proposed, would affect 108 helicopters of U.S. registry.

The FAA estimates the following costs to comply with this proposed AD:

The FAA estimates the following costs to do any replacements that would be required based on the results of the proposed inspection. The agency has no way of determining the number of helicopters that might need these replacements:

For helicopters that accomplished a balance correction in accordance with the instructions of the applicable AMM before the effective date of this AD, except those that accomplished a balance correction before the next flight after installing a new (zero total hours time-in-service) sliding flange and a new (zero total hours time-in-service) equipped splined sleeve, the corrective action that may be needed could vary significantly from helicopter to helicopter. The FAA has no data to determine the costs to accomplish the corrective action or the number of helicopters that may require corrective action.

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 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 that the 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 2023-25-14, Amendment 39-22641 ( 88 FR 89568, December 28, 2023); and

b. Adding the following new airworthiness directive:

Airbus Helicopters: Docket No. FAA-2026-4644; Project Identifier MCAI-2024-00418-R.

(a) Comments Due Date

The FAA must receive comments on this airworthiness directive (AD) by July 6, 2026.

(b) Affected ADs

This AD replaces AD 2023-25-14, Amendment 39-22641 (88 FR 89568, December 28, 2023).

(c) Applicability

This AD applies to all Airbus Helicopters Model EC130T2 helicopters, certificated in any category, as identified in European Union Aviation Safety Agency (EASA) AD 2024-0144, dated July 19, 2024 (EASA AD 2024-0144).

(d) Subject

Joint Aircraft System Component (JASC) Code 6510, Tail Rotor Drive Shaft.

(e) Unsafe Condition

This AD was prompted by a report of a crack in the tailboom. The FAA is issuing ( printed page 30260) this AD to address an excessive vibration level on the tail rotor drive shaft. The unsafe condition, if not addressed, could result in failure of the tail rotor drive shaft and loss of yaw control of the helicopter.

(f) Compliance

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

(g) Required Actions

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, EASA AD 2024-0144.

(h) Exceptions to EASA AD 2024-0144

(1) Where EASA AD 2024-0144 requires compliance in terms of flight hours, this AD requires using hours time-in-service.

(2) Where EASA AD 2024-0144 refers to its effective date, or where EASA AD 2024-0144 refers to November 6, 2023 [the effective date of EASA Emergency AD 2023-0190-E], this AD requires using the effective date of this AD.

(3) Where EASA AD 2024-0144 refers to “checks”, this AD requires replacing that text with “inspections”.

(4) Where paragraph (4) of EASA AD 2024-0144 specifies to “contact AH [Airbus Helicopters] to obtain approved instructions, and within the compliance time(s) specified therein, accomplish those instructions accordingly”, this AD requires replacing that text with “accomplish corrective action in accordance with a method approved by the Manager, 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, and within the compliance time(s) specified therein, accomplish those instructions accordingly.”

(5) This AD does not adopt the “Remarks” section of EASA AD 2024-0144.

(i) No Reporting Requirement

Although the material referenced in EASA AD 2024-0144 specifies to submit certain information to the manufacturer, this AD does not include that requirement.

(j) 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 (k) 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.

(k) Additional Information

For more information about this AD, contact Eric Rivera, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; phone: (773) 412-9048; email: eric.rivera01@faa.gov.

(l) Material Incorporated by Reference

(1) The Director of the Federal Register approved the incorporation by reference of the material identified in this AD 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 2024-0144, dated July 19, 2024.

(ii) [Reserved]

(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; website easa.europa.eu. You may find the EASA material on the EASA website ad.easa.europa.eu.

(4) You may view this material at FAA, Airworthiness Products Section, Operational Safety Branch, 10101 Hillwood Parkway, 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.

91 FR 30257