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-14791
Subject: AAR Manual of Standards and Recommended Practices Section N, Multi-Level Manual.
Summary: The Association of American Railroads Specially Equipped Freight Car Committee announces a new edition of the Manual of Standards and Recommended Practices, Section N, Multi-Level Manual. This printing includes implementation revisions and archiving of various documents resulting from recent committee meetings and industry comments.
Date: 06-01-2026
Effective Date: 06-01-2026
C-14801
Subject: Implementation of Revisions to MSRP Section E, BRAKES AND BRAKE EQUIPMENT, Standard S-400 Brake Equipment-Installation Specifications, revisions to the prohibition of specific shackles
Summary: This circular letter notifies the industry of revisions to Section E, Standard S-400, Brake Equipment-Installation Specifications. Comments were received and considered by the Brake Systems Committee, resulting in changes specifying the prohibition of splicing the hand brake chain. Standard S-400 is now implemented and effective immediately.
Date: 06-02-2026
Effective Date: 06-02-2026
C-14804
Subject: July 2026 Field and Office Manuals, Summary of Comments and Implementation Details
Summary: Several Circular Letters soliciting comments on proposed rule changes were issued in April and May 2026, with additional letters advising of approved changes effective July 1, 2026. The document recaps these letters, comments received, and indicates the rule changes for the Field Manual, noting which comments prompted changes and which did not.
Date: 06-19-2026
Effective Date: 06-19-2026
C-14805
Subject: Implementation Circular: Modifications to MSRP F, Sensors, S-920 AAR Component Identification (CID) Bar Code Standard – Appendix I – Tank Car Safety Relief Data Glossary
Summary: The Equipment Health Monitoring Committee (EHMC), in coordination with the Component Tracking Taskforce (CTTF) and the AAR Tank Car Committee, is issuing this implementation circular regarding a revision to Appendix I – Tank Car Safety Relief Devices in the AAR Manual of Standards and Recommended Practices (MSRP), Section F – Sensors. The revision introduces additional data elements and clarifying requirements for specific categories of tank car safety relief devices being added to the Component Registry by the Tank Car Committee, including combination devices, rupture disk devices, and vacuum relief valves.
Date: 06-22-2026
Effective Date: 06-22-2026
C-14807
Subject: Implementation of Revisions to Figure 106-C – Section 2 of the AAR Open Top Loading Rules Manual (OTLR)
Summary: The AAR’s Open Top Loading Rules Committee (OTLRC) has approved revisions to Section 2 of the OTLR manual for Figure 106-C, including edits to item numbers and descriptions related to loading rules. The implementation of these revisions is effective immediately and will be included in the next edition of the AAR’s OTLR manual.
Date: 06-25-2026
Effective Date: 06-25-2026
C-14808
Subject: Implementation of Revisions to load Scrap Metal, Loose and Baled in Gondolas, Figure 87 – Section 2 of the AAR Open Top Loading Rules Manual (OTLR)
Summary: The AAR’s Open Top Loading Rules Committee (OTLRC) has approved revisions to Section 2 of the OTLR manual for loading Scrap Metal, Loose and Baled, Figure 87 in Gondolas. These revisions include updated sketches and photos showing proper loading methods, deletion and movement of certain items, and edited notes on loading loose scrap metal.
Date: 06-29-2026
Effective Date: 06-29-2026
Call for Comment
C-14800
Subject: Solicitation of Comments for Revisions to MSRP Section E, BRAKES AND BRAKE EQUIPMENT, Standard S-374 Badge Plate for Showing Correct Dimensions for Body and Truck Brake Levers, revisions to update graphics.
Summary: This circular letter solicits comments for proposed revisions to Section E, Standard S-374 Badge Plate for Showing Correct Dimensions for Body and Truck Brake Levers, including updates to graphics to be more inclusive of different brake types and instructions for chains of special length.
Date: 06-02-2026
Comment Period: 30 Days
Notice of Circulars
C-14796
Subject: Informational Circular, Revisions to Field Manual Rules 47 and 48, Truck Bolsters and Truck Side Frames
Summary: At the April 2026 meeting of the Arbitration and Rules Committee, a proposal to revise Field Manual Rules 47 and 48 was reviewed and approved. The circular details the current and proposed changes to these rules regarding bolsters and side frames, which will be included in the July 1, 2026 updates to the Field Manual.
Date: 06-01-2026
Effective Date: 07-01-2026
C-14797
Subject: Informational Circular, Revisions to Field Manual Rules 15, 16, 18 and 21
Summary: At the April 2026 meeting of the Arbitration and Rules Committee, a proposal was advanced by the Coupling System and Truck Castings Committee to revise Field Manual Rules 15, 16, 18 and 21 to align with the recent updates to MSRP S-123 and S-124, was reviewed and approved.
Date: 06-01-2026
Effective Date: 06-01-2026
C-14798
Subject: Informational Circular, Revisions to Office Manual Rule 88.C.1.c
Summary: At the April 2026 meeting of the Arbitration and Rules Committee, a proposal was advanced to revise Office Manual Rule 88.C.1.c(4)(g), which was reviewed and approved. The revision is to provide clarification as a result of a request for interpretation.
Date: 06-01-2026
Effective Date: 06-01-2026
C-14799
Subject: Informational Circular, Revisions to Field Manual Rule 63, Automatic Equipment Identification
Summary: At the April 16, 2026 meeting of the Arbitration and Rules Committee, a proposal was advanced to revise Field Manual Rule 63, which was reviewed and approved. The document details the current and proposed revisions to Field Manual Rule 63.B Correct Repairs and introduces a new Field Manual Rule 63.B.10 regarding brackets applied to steel and aluminum cars.
Date: 06-02-2026
Effective Date: 07-01-2026
C-14802
Subject: Updated Views and Interpretations for AAR MSRP Section J, Specification for Quality Assurance M-1003
Summary: The Association of American Railroads (AAR) Quality Assurance Committee (QAC) has updated the Views and Interpretations document for Section J of the AAR Manual of Standards and Recommended Practices (MSRP), Specification M-1003, to improve clarity. The QAC regularly reviews all interpretations and integrates them directly into Specification M-1003 when appropriate, while some interpretations remain in the Views and Interpretations document for reference.
Date: 06-12-2026
Effective Date: 06-12-2026
C-14803
Subject: Informational Circular, Car Repair Facility Labor Rate – Effective July 1, 2026
Summary: The Car Repair Facility Labor Rate effective July 1, 2026 is $178.63 per hour, an increase of $4.08 (or 2.34%) from the labor rate estimated on April 1, 2026. The increase is from general wage increases for most railroads, primarily those included in national negotiations, and will be reflected in the July 1, 2026 release of the AAR Office Manual.
Date: 06-15-2026
Effective Date: 07-01-2026
C-14806
Subject: Fall 2026 AAR Technical Committee Meetings
Summary: AAR meetings planned for the second half of 2026 are listed, including dates, locations, and contact information for various technical committees. Information for individual Technical Committee Meetings in Colorado Springs in August can be found online.
Date: 06-22-2026
Effective Date: 06-22-2026
MARS Meeting
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