Airworthiness Directive for Bell Textron Canada Limited Model 505 Helicopters

Proposed Rule

Airworthiness Directives; Bell Textron Canada Limited Helicopters

A Proposed Rule by the Federal Aviation Administration on 04/08/2026

• This document has a comment period that ends in 48 days.
  (05/26/2026) View Comment Instructions

• PDF

• Document Details

• Document Dates

- Table of Contents

• Public Comments
• Regulations.gov Data

- Sharing

• Print
• Other Formats
• Public Inspection Published Document: 2026-06788 (91 FR 17772) Document Headings ###### Department of Transportation

Federal Aviation Administration

1. 14 CFR Part 39
2. [Docket No. FAA-2026-3477; Project Identifier MCAI-2025-01195-R]
3. RIN 2120-AA64

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to supersede Airworthiness Directive (AD) AD 2024-02-55, which applies to certain Bell Textron Canada Limited (BTCL) Model 505 helicopters. AD 2024-02-55 requires initial and recurring inspections of the vertical stabilizer top end cap assembly and corrective action if a crack is found. Since the FAA issued AD 2024-02-55, the manufacturer introduced a new one-piece vertical stabilizer machined top end cap assembly, which is implemented during production, and designed a new replacement for the vertical stabilizer machined top end cap assembly currently in service. This proposed AD would continue to require the inspection requirements of AD 2024-02-55 and would limit the applicability to exclude certain serial numbered BTCL Model 505 helicopters with an improved design vertical stabilizer top end cap installed at production. This proposed AD would also require replacing the vertical stabilizer top end cap assembly with an improved design top end cap assembly, which would constitute terminating action for the recurring detailed visual inspections. The FAA is proposing this AD to address the unsafe condition on these products.

DATES:

The FAA must receive comments on this NPRM by May 26, 2026.

ADDRESSES:

You may send comments, using the procedures found in 14 CFR 11.43 and 11.45, by any of the following methods:

• Federal eRulemaking Portal: Go to regulations.gov. Follow the instructions for submitting comments.
• Fax: (202) 493-2251.
• Mail: U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue SE, Washington, DC 20590.
• Hand Delivery: Deliver to Mail address above between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. AD Docket: You may examine the AD docket at regulations.gov under Docket No. FAA-2026-3477; 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 NPRM, the mandatory continuing airworthiness information (MCAI) any comments received, and other information. The street address for Docket Operations is listed above.

Material Incorporated by Reference:

• For Transport Canada material identified in this proposed AD, contact Transport Canada, Transport Canada National Aircraft Certification, 159 Cleopatra Drive, Nepean, Ontario, K1A 0N5, CANADA; telephone 888-663-3639; email: TC.AirworthinessDirectives-Consignesdenavigabilite.TC@tc.gc.ca; ( printed page 17773) internet tc.canada.ca/en/aviation. You may find the Transport Canada material on the Transport Canada website at wwwapps.tc.gc.ca/Saf-Sec-Sur/2/cawis-swimn/ad_qs1.aspx.
• 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.

FOR FURTHER INFORMATION CONTACT:

Promita Dey, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; phone: (913) 563-8269; email: promita.dey@faa.gov.

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-2026-3477; Project Identifier MCAI-2025-01195-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 Promita Dey, 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 2024-02-55, Amendment 39-22674 (89 FR 14576, February 28, 2024) (AD 2024-02-55), for BTCL Model 505 helicopters having serial numbers 65011 and subsequent. AD 2024-02-55 was prompted by an MCAI issued by Transport Canada, which is the aviation authority for Canada. Transport Canada issued Transport Canada Emergency AD CF-2024-03, dated January 25, 2024 (Transport Canada AD CF-2024-03), to correct an unsafe condition identified as reports of cracked vertical stabilizer top end cap assemblies.

AD 2024-02-55 requires initial and recurring inspections of the vertical stabilizer top end cap assembly, and if a crack is found, replacement of the top end cap. The FAA issued AD 2024-02-55 to address cracking in the vertical stabilizer top end cap assembly. This condition, if not addressed, could result in the antenna or tuning weight departing from the helicopter and impacting and damaging the tail rotor, which could result in the loss of directional control of the helicopter.

Actions Since AD 2024-02-55 Was Issued

Since the FAA issued AD 2024-02-55, Transport Canada superseded Transport Canada AD CF-2024-03 and issued Transport Canada AD CF-2025-32, dated July 2, 2025 (Transport Canada AD CF-2025-32) (also referred to as the MCAI). The MCAI states that a new one-piece vertical stabilizer machined top end cap assembly, having part number (P/N) SLS-030-701-149, was implemented into the Bell 505 production line, and a new machined top end cap assembly, P/N SLS-704-701-101, was developed as a replacement for the top end cap assembly P/N SLS-030-701-125 that is currently in service. The MCAI requires repetitive inspections of the vertical stabilizer top end cap assembly until the required replacement with a new machined top end cap assembly, P/N SLS-704-701-101, which is considered terminating action for the repetitive inspections.

You may examine the MCAI in the AD docket at regulations.gov under Docket No. FAA-2026-3477.

Material Incorporated by Reference Under 1 CFR Part 51

The FAA reviewed Transport Canada AD CF-2025-32, which specifies procedures for accomplishing a one-time detailed visual inspection of the vertical stabilizer top end cap assembly for cracking; replacing any cracked vertical stabilizer top end cap assembly; repetitively inspecting vertical stabilizer top end cap assembly P/N SLS-030-701-125; and replacing vertical stabilizer top end cap assembly P/N SLS-030-701-125 with vertical stabilizer top end cap assembly P/N SLS-704-701-101.

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 proposing 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 would continue to require the inspection requirements of AD 2024-02-55 and would also require accomplishing the actions specified in Transport Canada AD CF-2025-32, described previously as incorporated by reference, except for any differences identified as exceptions in the regulatory text of this proposed 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

Where the material referenced in Transport Canada AD CF-2025-32 specifies to contact the manufacturer if the drilled holes can no longer go beyond the allowable dimensions, this AD requires corrective action to be done in accordance with a method approved by the Manager, International Validation Branch, FAA; or Transport Canada; or Bell Textron Canada Limited Transport Canada Design Organization Approval (DOA). If approved by the DOA, the approval must include the DOA-authorized signature. ( printed page 17774)

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 Transport Canada AD CF-2025-32 by reference in the FAA final rule. This proposed AD would, therefore, require compliance with Transport Canada AD CF-2025-32 in its entirety through that incorporation, except for any differences identified as exceptions in the regulatory text of this proposed AD. Material required in Transport Canada AD CF-2025-32 for compliance will be available at regulations.gov under Docket No. FAA-2026-3477 after the FAA final rule is published.

Costs of Compliance

The FAA estimates that this AD, if adopted as proposed, would affect 150 helicopters of U.S. registry.

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

| Action | Labor cost | Parts cost | Cost per
product | Cost on U.S. operators |
| --- | --- | --- | --- | --- |
| Initial inspection of vertical stabilizer top end assembly | 2 work-hours × $85 per hour = $170 | $0 | $170 | $25,500 |
| Recurring inspections of vertical stabilizer top end assembly | 1 work-hour × $85 per hour = $85 | 0 | 85 | 12,750 |
| Replacement of the vertical stabilizer top end assembly | 6 work-hours (not including 16 hours to cure) × $85 per hour = $510 | 2,000 | 2,510 | 376,500 |
The FAA has included all known costs in its cost estimate. According to the manufacturer, however, some of the costs of this proposed 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 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.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Incorporation by reference
• Safety

The Proposed Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 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 2024-02-55, Amendment 39-22674 (89 FR 14576, February 28, 2024); and

b. Adding the following new airworthiness directive:

Bell Textron Canada Limited: Docket No. FAA-2026-3477; Project Identifier MCAI-2025-01195-R.

(a) Comments Due Date

The FAA must receive comments on this airworthiness directive (AD) by May 26, 2026.

(b) Affected ADs

This AD replaces AD 2024-02-55, Amendment 39-22674 (89 FR 14576, February 28, 2024).

(c) Applicability

This AD applies to Bell Textron Canada Limited Model 505 helicopters, certificated in any category, as identified in Transport Canada AD CF-2025-32, dated July 2, 2025 (Transport Canada AD CF-2025-32).

(d) Subject

Joint Aircraft System Component (JASC) Code: 5530, Vertical Stabilizer Structure.

(e) Unsafe Condition

This AD was prompted by multiple occurrences of the vertical stabilizer top end cap assembly being found cracked, with some cases including the departure of the navigation/very high frequency omni-directional range/glide slope antenna and tuning weight from the helicopter during flight. The FAA is issuing this AD to address cracking in the vertical stabilizer top end cap assembly. The unsafe condition, if not addressed, could result in the antenna or tuning weight departing from the helicopter and impacting and damaging the tail rotor, which could result in the loss of directional control of the helicopter.

(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, Transport Canada AD CF-2025-32.

(h) Exceptions to Transport Canada AD CF-2025-32

(1) Where Transport Canada AD CF-2025-32 refers to its effective date, this AD requires using the effective date of this AD. ( printed page 17775)

(2) Where Transport Canada AD CF-2025-32 requires compliance in terms of hours air time, this AD requires using hours time-in-service.

(3) Where the material referenced in Transport Canada AD CF-2025-32 specifies discarding parts, this AD requires removing those parts from service.

(4) Where the material referenced in Transport Canada AD CF-2025-32 specifies damage, for the purposes of this AD, damage can be indicated by, but not limited to, cracking.

(5) Where the material referenced in Transport Canada AD CF-2025-32 specifies to contact the manufacturer if the drilled holes can no longer go beyond the allowable dimensions, this AD requires corrective action in accordance with a method approved by the Manager, International Validation Branch, FAA; or Transport Canada; or Bell Textron Canada Limited Transport Canada Design Organization Approval (DOA). If approved by the DOA, the approval must include the DOA-authorized signature.

(i) No Reporting Requirement

Although the service material referenced in Transport Canada AD CF-2025-32 specifies submitting certain information to the manufacturer, this AD does not include that action.

(j) Credit for Previous Actions

This paragraph provides credit for the actions required by paragraph 1. of Transport Canada AD CF-2025-32, if those actions were performed before the effective date of this AD using Bell Textron Canada Limited Alert Service Bulletin (ASB) 505-24-38, dated January 24, 2024.

(k) 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 (l) 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.

(l) Additional Information

For more information about this AD, contact Promita Dey, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; phone: (913) 563-8269; email: promita.dey@faa.gov.

(m) 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) Transport Canada AD CF-2025-32, dated July 2, 2025.

(ii) [Reserved]

(3) For Transport Canada material identified in this AD, contact Transport Canada National Aircraft Certification, 159 Cleopatra Drive, Nepean, Ontario, K1A 0N5, Canada; phone 888-663-3639; email TC.AirworthinessDirectives-Consignesdenavigabilite.TC@tc.gc.ca; internet tc.canada.ca/en/aviation. You may find the Transport Canada material on the Transport Canada website at wwwapps.tc.gc.ca/Saf-Sec-Sur/2/cawis-swimn/ad_qs1.aspx.

(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 April 6, 2026.

Steven W. Thompson,

Acting Deputy Director, Compliance & Airworthiness Division, Aircraft Certification Service.

[FR Doc. 2026-06788 Filed 4-7-26; 8:45 am]

BILLING CODE 4910-13-P

Published Document: 2026-06788 (91 FR 17772)