About AAR Circular Letters
Circular letter summaries are produced monthly by Greenbrier Management Services Group.
AAR circular letters provide information of general applicability to the railroad industry, including proposed and final rules, revisions, standards and recommended practices, and calls for comments. These summaries provide the main points of circular letters issued in the prior month, as well as important implementation deadlines.
For access to the complete circular letter, please go to my.aar.org/circulars. Circular letters are a fee-based service provided by the AAR’s Transportation Technology Center Incorporated (TTCI). You may subscribe online at publications@aar.com or call 719.584.0538.
Implementation Circulars
C-14746
Subject: Implementation of Revised MSRP Section B, FREIGHT CAR DRAFT COMPONENTS, 2026
Summary: The AAR Equipment Engineering Committee (EEC) announces a new edition of the MSRP, Section B, FREIGHT CAR DRAFT COMPONENTS. The revised MSRP Section B is available in both printed and electronic versions, with current pricing available online, and includes relocated standards from MSRP B to MSRP S-III.
Date: 03-02-2026
Effective Date: 03-02-2026
C-14747
Subject: Implementation of Revised MSRP Section S-III, COUPLER AND YOKE DETAILS, 2026
Summary: The AAR Coupling System and Truck Castings Committee (CSTCC) announces a new edition of the MSRP, Section S-III, COUPLER AND YOKE DETAILS. The revised MSRP Section S-III is now available in both printed and electronic versions, with current pricing available online, and includes relocated standards from MSRP B to MSRP S-III.
Date: 03-02-2026
Effective Date: 03-02-2026
C-14754
Subject: Implementation of Editorial Revisions to MSRP Section C-I, CAR CONSTRUCTION FUNDAMENTALS AND DETAILS, Standard S-2057 Draft Arrangements, 24 5/8-in. Pocket, regarding dimensions on Figures 5.1 and 8.1
Summary: This circular letter notifies the industry of editorial revisions to Section C-I, CAR CONSTRUCTION FUNDAMENTALS AND DETAILS, Standard S-2057 Draft Arrangements, 24 5/8-in. Pocket. The ‘A’ dimension in Figure 5.1 was updated to reference the coupler horn rather than the striker face, and Figure 8.1 was updated to include the dimension from the coupler horn to the connector pin support (to the outermost bolt).
Date: 03-09-2026
Effective Date: 03-09-2026
C-14758
Subject: Implementation Circular: Modifications to MSRP F, Sensors, S-920 AAR Component Identification (CID) Bar Code Standard – Appendix A: Wheel Set Data Glossary
Summary: This Implementation Circular advises the industry of approved modifications to Appendix A of the AAR MSRP, Section F – Sensors / S-920. It modernizes the layout of Appendix A and clarifies data submission requirements for initial component registration, field registration, and instances requiring human-readable text on component identification (CID) labels.
Date: 03-27-2026
Effective Date: 03-27-2026
CPC-1440
Subject: Implementation of the Revision to MSRP Section C Part III, M-1002, Specifications for Tank Cars, Chapter 2, Paragraph 2.2.13.3
Summary: Comments received from CPC-1437 have been addressed. This is final action on revisions affecting Chapter 2, Paragraph 2.2.13.3. Tank cars offered in a purged state under pressure may use, in addition to regulatory required marking, a yellow, plastic-strap, weather-proof security seal with the warning “Low Oxygen Atmosphere – Can Be Deadly” with asphyxiation image. Warning labels shall be in English, French and Spanish. The seals may be affixed to the car in two locations to ensure redundancy and visibility for a potential entrant: on the manway handle or service equipment (if no manway) at the top of the car, on the platform railing near the manway, and only apply the seals on the upper handles. A tag must be made of any material capable of withstanding without deterioration of substantial reduction in effectiveness a 30-day exposure to open weather conditions.
Date: 03-10-2026
Effective Date: 03-10-2026
CPC-1441
Subject: Implementation of the Revision to MSRP Section C Part III, M-1002, Specifications for Tank Cars, Appendix B, Table B.2
Summary: Comments received from CPC-1438 have been addressed. This is final action on the revision effecting Appendix B, Table B.2, activity code C6r, allowing certification in the category of one service equipment and granting approval to all other categories for this activity code.
Date: 03-10-2026
Effective Date: 03-10-2026
CPC-1442
Subject: Implementation of the Revision to MSRP Section C Part III, M-1002, Specifications for Tank Cars, Appendix B, 3.6- Demonstration Capability: C6r
Summary: Comments received from CPC-1439 have been addressed. This action will allow facilities to accomplish the C6r demonstrations by either displaying modifications on tank car service equipment or by removing and replacing the service equipment and demonstrating the administration process of the modification.
Date: 03-10-2026
Effective Date: 03-10-2026
Call for Comment
C-14748
Subject: Solicitation of Comments for Revisions to MSRP Section S, CASTING DETAILS, Specification M-214, Side Frames and Bolsters Used and Reconditioned – Classification and Repair
Summary: This circular letter solicits comments for revisions proposed to MSRP Section S, Specification M-214, Side Frames and Bolsters Used and Reconditioned – Classification and Repair. The changes include updated welding requirements, definitions, inspection clarifications, and reconditioning marking requirements, with proposed updates highlighted in the attached file.
Date: 03-03-2026
Comment Period: 30 Days
C-14749
Subject: Solicitation of Comments for Revisions to MSRP Section S-I, CASTING DETAILS, Specification M-201, Castings Steel
Summary: The purpose of this circular letter is to solicit comments for revisions proposed to Section S-I, Specification M-201, Castings Steel, regarding updates to definitions, references, and section 7.0 – mechanical property tests and impact tests. The summary of changes includes added definitions, a references section, reorganization of section 7.0, and updates to appendices and checklists.
Date: 03-03-2026
Comment Period: 30 Days
C-14751.1
Subject: Solicitation of Comments for Revisions to MSRP Section C-II Design, Fabrication, and Construction of Freight Cars, M-1001, Chapter 5 Fabrication and Construction
Summary: This circular solicits comments for revisions proposed to Section C-II Design, Fabrication, and Construction of Freight Cars, Specification M-1001, Chapter 5 Fabrication and Construction. The update aims to consolidate workmanship requirements by moving unique items from retired AAR Standards S-2034 into Chapter 5, with editorial changes highlighted in the attached draft.
Date: 03-05-2026
Comment Period: 30 Days
C-14752
Subject: Solicitation of Comments for Revisions to MSRP Section C-II Design, Fabrication, and Construction of Freight Cars, M-1001, Chapter 3 Materials
Summary: This circular letter solicits comments for a proposed revision to Section C-II Design, Fabrication, and Construction of Freight Cars, Specification M-1001, Chapter 3 Materials – Body Structure. The update aims to add additional criteria to satisfy M-1001 impact toughness requirements, with the revised sentence highlighted in the attached draft of Chapter 3.
Date: 03-05-2026
Comment Period: 30 Days
C-14753
Subject: Solicitation of Comments for Revisions to MSRP Section C-I, CAR CONSTRUCTION FUNDAMENTALS AND DETAILS, Standard S-2058 Non-Hydraulic Energy Management Systems (EMS) with Buff Travel of 6″ or more
Summary: This circular letter solicits comments for revisions to MSRP Section C-I, CAR CONSTRUCTION FUNDAMENTALS AND DETAILS, Standard S-2058 Non-Hydraulic Energy Management Systems (EMS) with Buff Travel of 6″ or more. A detailed drawing and reference table of an additional EMS (Energy Management System) pocket EMS-4 (STRATO SC-5210 DRAFT PACK WITH SC-2019 BUFF PACK) has been added.
Date: 03-09-2026
Comment Period: 30 Days
C-14759
Subject: Solicitation of Comments for Revisions to Recommended Practices RP-803 to RP-831; MSRP Section N – Multi-Level Manual
Summary: This circular letter solicits comments for revisions proposed to Recommended Practices RP-803 to RP-831, MSRP Section N – Multi-Level Manual. It lists the specific recommended practices being revised and states that comments received within 30 days will be considered prior to taking action.
Date: 03-31-2026
Comment Period: 30 Days
CPC-1444
Subject: Solicitation for comment on Proposed Revisions to MSRP Section C Part III, M-1002, Specifications for Tank Cars, Appendix D, paragraph 4.0
Summary: The proposed revision clarifies that any service equipment not utilized after 6 months from the date of manufacture must be tested according to OEM recommendations. The revision includes removal of a note about pressure relief valves, changes to a reference sentence, and an added paragraph about retesting pressure relief valves older than 6 months.
Date: 03-12-2026
Comment Period: 30 Days
Notice of Circulars
C-14750
Subject: Informational Circular, Car Repair Facility Labor Rate – Effective April 1, 2026
Summary: The Car Repair Facility Labor Rate effective April 1, 2026 is $174.55, an increase of $0.46 (or 0.26%) from the labor rate estimated for January 1, 2026. The increase is primarily due to new independent labor agreements finalized in the first quarter of 2026, including retroactive wage adjustments and updated health and welfare rates for independent contracts.
Date: 03-04-2026
Effective Date: 04-01-2026
C-14755
Subject: 2026 AAR M-1003 Quality Assurance Auditor Training Class Schedule Update
Summary: The Association of American Railroads (AAR) Quality Assurance Committee (QAC) has updated the schedule for the 2026 AAR M-1003 Quality Assurance Auditor Training classes. The document provides details on class dates, locations, registration links, and descriptions for both Basic and Advanced Auditor Training classes.
Date: 03-16-2026
Effective Date: 03-16-2026
C-14756
Subject: Informational Circular, Canadian Car Repair Facility Labor Rate – Effective April 1, 2026
Summary: The Canadian Car Repair Billing Labor Rate calculation for April 1, 2026 is $267.18 CAD, reflecting a decrease from the previous calculation. This change will be reflected in the April 1, 2026 release of the Canadian Price Master.
Date: 03-16-2026
Effective Date: 04-01-2026
C-14757
Subject: Update to the Car Repair Billing Data Exchange Schedule, Effective April 1, 2026
Summary: This AAR Circular Letter updates and supersedes C-14699 issued December 9, 2025. It announces a change to the planned April 2026 CRBDX run dates to accommodate a Railinc holiday, revising the production and date out to Monday, April 6.
Date: 03-23-2026
Effective Date: 04-01-2026
CPC-1443
Subject: Cracks found on 6F Stainless Steel Nuts
Summary: This circular informs Tank Car owners about potentially defective 6F stainless steel nuts supplied by Fastenal that have shown crack progression when applying required torque values. The nuts of concern are 5/8″, 1″ and 1 (1/8)” ASTM A194 Grade 6F stainless steel heavy hex nuts produced with the manufacturer code “WL”.
Date: 03-10-2026
Effective Date: 03-10-2026
AAR Hazmat and Tank Car Committee Meeting
The Greenbrier Companies is a Proud Exhibitor and Sponsor
April 13-16 | Nashville, TN
Greenbrier’s Regulatory Services Group
Peace of mind for your business.
Led by Diana Aylward, Greenbrier’s Regulatory Management Group provides regulatory, engineering, process consulting and advocacy support to the railcar repair industry and the petrochemical rail shipper community.
Our core services include:
- DOT Compliance Assessments (Corporate and Plant)
- DOT Hazardous Materials Training (Corporate and Plant)
- Federal Claims Mitigation Support (e.g., FRA and PHMSA)
- Regulatory Counsel and Policy Advocacy
- Railcar Repair Management (Design Review, Drawings, Engineering and AAR Approval Administration)
- Tank Car Reliability & Maintenance Programs (per 49 CFR Subpart F of Part 180)
- Tank Car Maintenance Data Collection & Performance Analysis
For inquiries about these summaries or any of our services, please reach out to: regulatoryservices@gbrx.com
About Greenbrier Management Services (GMS)
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