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-14621
Subject: Implementation of an Editorial Revision to MSRP Section T-III, INTERCHANGE STANDARDS FOR FUEL TENDER COMPONENTS Standard, S-5025 GASEOUS NATURAL GAS SUPPLY HOSE UNIT FOR FUEL TENDERS
Summary: This circular letter notifies the industry of an editorial revision applied to the title of Manual of Standards and Recommended Practices (MSRP), Section T-III, Standard, S-5025 GASEOUS NATURAL GAS SUPPLY HOSE UNIT FOR FUEL TENDERS. The implementation version updates the title of the support standard to specifically identify the natural gas supply hose standard and the revised S-5025 is appended to this circular and effective immediately.
Date: 2025-10-01
Effective Date: 2025-10-01
C-14622
Subject: Implementation of Revisions to MSRP Section H-II, ROLLER BEARING MANUAL, Standards S-735, S-736, S-737, S-738, and S-740, Spall and Gouge Criteria, Polymer Cages, and Temperature Measurements
Summary: This circular letter notifies the industry of revisions to MSRP Section H-II, Roller Bearing Manual, Standards S-735, S-736, S-737, S-738, and S-740, including updates to spall and gouge criteria, additional requirements for polymer cages, and updates to measurement temperature criteria. Comments were received and considered, and the revised standards are now implemented and effective immediately.
Date: 2025-10-07
Effective Date: 2025-10-07
CPC 1432
Subject: Implementation of changes to MSRP Section C-III, Specification for Tank Cars (M-1002), Appendix A Section 6.4
Summary: The Tank Car Committee (TCC) has implemented changes to MSRP Section C-III, Specification for Tank Cars (M-1002), Appendix A. These changes include requirements for gauging devices with replaceable gauge rods to be marked with manufacturer details, specific gravity, unique serial number, original date of manufacture, and specific gravity and outage values on decals for gauge rods with universal markings.
Date: 2025-10-10
Effective Date: 2025-10-10
CPC-1433
Subject: Implementation of changes to MSRP Section C-III, Specification for Tank Cars (M-1002), Appendix B Section 4.7
Summary: The Tank Car Committee (TCC) has implemented the addition of following to MSRP Section C-III, Specification for Tank Cars (M-1002), Appendix B. 4.7 Maintaining Certification includes that if a facility is more than 18 months from a prior audit date, the facility will be scheduled for an audit regardless of the application and/or ballot status for the facility.
Date: 2025-10-10
Effective Date: 2025-10-10
CPC-1434
Subject: Implementation of Revisions to MSRP Section C Part III, M-1002, Specifications for Tank Cars, Proposed Appendix A
Summary: Comments received from CPC-1430 have been addressed. This is the final action on revisions affecting Appendix A, Tank Car Valves and Fittings, of M-1002, Specifications for Tank Cars. The Tank Car Committee authorized the replacement of table A.2 in Appendix A with D.6 from Appendix D- (AAR component tracking effective dates) in the MSRP-CIII, Specifications of Tank Cars (M-1002). This table now includes serial numbers marked at the time of initial manufacturing or assembling and AAR component tracking effective dates. The committee additionally approved the addition of “original valve date of manufacture (applies only to valve manufactured after [effective date])” as a required markings for Pressure Relief Valve (6.2.1), Combination Devices (6.2.2), Rupture Disc Devices (6.2.3.1), Vacuum Relief Valve (6.2.4), Liquid and Vapor Valves (6.3.1), Pressure Regulator Valves (6.3.2), Excess Flow Valves (6.3.3), and “original date of manufacture (applies only to device manufactured after [effective date])” to Liquid Level Control and Gauging Device (6.4.1, 6.4.1.1).
Date: 2025-10-10
Effective Date: 2025-10-10
C-14626
Subject: Implementation of Revisions to MSRP Section C-I, CAR CONSTRUCTION FUNDAMENTALS AND DETAILS, new Standard S-2058 Non-Hydraulic Energy Management Systems (EMS) with Buff Travel of 6″ or more
Summary: This circular letter notifies the industry of revisions to MSRP Section C-I, CAR CONSTRUCTION FUNDAMENTALS AND DETAILS, regarding the addition of new Standard S-2058 Non-Hydraulic Energy Management Systems (EMS) with Buff Travel of 6″ or more. The standard includes detailed drawings and reference tables for three new EMS pockets and is now implemented and effective immediately.
Date: 2025-10-15
Effective Date: 2025-10-15
C-14632
Subject: Implementation of Revisions to MSRP Section C-I, CAR CONSTRUCTION FUNDAMENTALS AND DETAILS, Standard S-234, and Section C-II M-1001 DESIGN, FABRICATION, AND CONSTRUCTION OF FREIGHT CARS, regarding jacking and lifting requirements
Summary: This circular letter notifies the industry of revisions to MSRP Section C-I, CAR CONSTRUCTION FUNDAMENTALS AND DETAILS, Standard S-234 Jacking and Lifting of Freight Cars, and Section C-II M-1001 DESIGN, FABRICATION, AND CONSTRUCTION OF FREIGHT CARS, regarding jacking and lifting requirements. The revisions improve the description of jacking and lifting requirements based on issues encountered during handling of recently built cars, including updated guidance, electronic jack gage availability, and changes to design chapters.
Date: 2025-10-21
Effective Date: 2025-10-21
C-14642
Subject: Implementation of Revised MSRP Section I, Intermodal Equipment Manual, 2025
Summary: Announces a new edition of the Intermodal Equipment Manual with updates since August 2018.
Date: 2025-10-23
Effective Date: 2025-10-23
C-14653
Subject: Implementation of Revisions to Figure 55-A – Section 3 of the AAR Open Top Loading Rules Manual (OTLR)
Summary: Approved revisions to Figure 55-A, adding new item ‘Alt E1’ and changing an existing item.
Date: 2025-10-28
Effective Date: 2025-10-28
C-14654
Subject: Implementation of new Figures 83-C, 200-E and 200-F – Section 6 of the AAR Open Top Loading Rules Manual (OTLR)
Summary: Addition of new figures for M88A2, EHETS, and METS.
Date: 2025-10-28
Effective Date: 2025-10-28
C-14655
Subject: Implementation of Revisions to Figures 58-C, 116, and 117 – Section 5 of the AAR Open Top Loading Rules Manual (OTLR)
Summary: Changes to item numbers, added new items, and edits to descriptions related to web tie-down assemblies and mats.
Date: 2025-10-28
Effective Date: 2025-10-28
C-14657
Subject: Implementation of Revisions to Figures 22-D, 40-A and 154-A – Section 2 of the AAR Open Top Loading Rules Manual (OTLR)
Summary: Changes to descriptions and sketches for clarity.
Date: 2025-10-29
Effective Date: 2025-10-29
C-14658
Subject: Implementation of Revisions to General Rule 28, Glossary, and Appendix F – Section 1 of the AAR Open Top Loading Rules Manual (OTLR)
Summary: Additions and changes to rules and definitions related to buffer cars, impact tests, and restraint values.
Date: 2025-10-29
Effective Date: 2025-10-29
C-14660
Subject: Implementation of Revisions to General Rules 5, 35 and 36 – Section 1 of the AAR Open Top Loading Rules Manual (OTLR)
Summary: Deletions and additions to rules related to load restraint and field impact testing.
Date: 2025-10-29
Effective Date: 2025-10-29
C-14663
Subject: Notice of Implementation to archive Figure 190 – Section 3 of the AAR Open Top Loading Rules Manual (OTLR)
Summary: Archiving Figure 190 due to non-use and safety issues.
Date: 2025-10-30
Effective Date: 2025-10-30
C-14664
Subject: Implementation of Revisions to Figures 9-B and 14 – Section 2 of the AAR Open Top Loading Rules Manual (OTLR)
Summary: Edits to Item C labeling and updates to clamping piece photos and verbiage.
Date: 2025-10-30
Effective Date: 2025-10-30
Call for Comment
C-14624
Subject: Solicitation of Comments, Proposal to Modify Car Repair Billing Data Exchange Run Dates – Effective January 1, 2027
Summary: The circular proposes modifications to the Car Repair Billing Data Exchange (CRBDX) run dates, detailing current and proposed schedules for inbound and outbound repair bill dates. It invites comments from subscribers within 30 days for consideration before final implementation.
Date: 2025-10-08
C-14627
Subject: Solicitation of Comments for Revisions to MSRP B, FREIGHT CAR DRAFT COMPONENTS, Specification M-118, regarding archiving of M-118, creation of new standards S-123 and S-124, migration to MSRP S-III and addition of C-10A alternate end detail
Summary: This circular letter solicits comments for revisions related to Section B, Specification M-118, Pin, Coupler Knuckle Pivot and Coupler Shank Connecting, Steel, including creation of new standards S-123 and S-124, migrating the standards to MSRP S-III, and addition of C-10A pin alternate end detail. It proposes to separate and redesignate specification M-118 into two new standards, S-123 and S-124, and to archive M-118, with updates highlighted in attached files.
Date: 2025-10-20
C-14628
Subject: Solicitation of Comments For MSRP Section T-III, INTERCHANGE STANDARDS FOR FUEL TENDER COMPONENTS, Proposed New Standard, S-5033 GASEOUS HYDROGEN SUPPLY HOSE UNIT FOR FUEL TENDERS
Summary: This circular letter seeks comments on a new standard proposed for addition to MSRP Section T-III, INTERCHANGE STANDARDS FOR FUEL TENDER COMPONENTS. Draft standard S-5033 GASEOUS HYDROGEN SUPPLY HOSE UNIT FOR FUEL TENDERS was developed to establish new fuel interface hose requirements necessary for tenders to safely supply gaseous hydrogen to applicable locomotives.
Date: 2025-10-21
C-14629
Subject: Solicitation of Comments, Revisions to Field Manual, Rules 4 and 83, Missing 4-Pressure Receiver Dust Covers
Summary: At the October 2025 meeting of the Arbitration and Rules Committee, a proposal to revise Field Manual Rules 4 and 83 was reviewed and approved. The revisions include changes to rules regarding the 4-Pressure Single Car Test and the replacement of receivers with missing dust covers.
Date: 2025-10-21
C-14630
Subject: Solicitation of Comments, Revisions to Field Manual, Rule 5
Summary: At the October 2025 meeting of the Arbitration and Rules Committee, a proposal to revise Field Manual Rule 5 was reviewed and approved. The circular details the current and proposed revisions to Field Manual Rule 5.E.23 and 5.F Job Codes, and solicits comments to be sent within 30 days for consideration.
Date: 2025-10-21
C-14631
Subject: Solicitation of Comments, Revisions to Field Manual, Rule 5, Job Code 1245
Summary: At the October 2025 meeting of the Arbitration and Rules Committee, a proposal was advanced by the Car Repair Billing Committee to revise Field Manual Rule 5, Job Code 1245 to align the Job Code with the description, which was reviewed and approved. Comments are solicited in accordance with Rule 123 and should be sent within 30 days for consideration.
Date: 2025-10-21
C-14633
Subject: Solicitation of Comments, Revisions to Field Manual, Rule 36, Bearing Lateral Inspection
Summary: At the October 2025 meeting of the Arbitration and Rules Committee, a proposal was advanced by the WABL Committee to revise Field Manual Rule 36, which was reviewed and approved. The circular details the current and proposed revisions to Field Manual Rule 36 regarding bearing lateral inspection and excessive lateral movement of bearing cups.
Date: 2025-10-21
C-14634
Subject: Solicitation of Comments, Revisions to Field Manual, Rule 62
Summary: At the October 2025 meeting of the Arbitration and Rules Committee, a proposal to revise Field Manual Rule 62 was reviewed and approved. Comments are solicited in accordance with Rule 123 and should be sent within 30 days for consideration.
Date: 2025-10-21
C-14635
Subject: Solicitation of Comments, Revisions to Field Manual, Rule 63
Summary: At the October 2025 meeting of the Arbitration and Rules Committee, a proposal was approved to revise Field Manual Rule 63 due to low usage of Job Code 4344. The revision involves removing certain billing requirements related to the end-of-train device AEI and Job Code 4344.
Date: 2025-10-21
C-14636
Subject: Solicitation of Comments, Revisions to Field Manual, Rule 64, Job Code 4923
Summary: At the October 2025 meeting of the Arbitration and Rules Committee, a proposal to revise Field Manual Rule 64 due to low usage of Job Code 4923 was reviewed and approved. Comments are solicited in accordance with Rule 123 and should be sent within 30 days for consideration.
Date: 2025-10-21
C-14637
Subject: Solicitation of Comments, Revisions to Field Manual, Rule 53
Summary: At the October 2025 meeting of the Arbitration and Rules Committee, a proposal to revise Field Manual Rule 53 was reviewed and approved. The circular details the current and proposed revisions to Field Manual Rule 53, including specific criteria for cracks and defects in platform crossover boards and running boards.
Date: 2025-10-21
C-14638
Subject: Solicitation of Comments, Revisions to Field Manual, Rule 18, Job Code 2254
Summary: At the October 2025 meeting of the Arbitration and Rules Committee, a proposal to revise Field Manual Rule 18 to eliminate condition code 1 for non-M-216 compliant knuckles was reviewed and approved. Comments are solicited within 30 days for consideration.
Date: 2025-10-22
C-14639
Subject: Solicitation of Comments, Revisions to Field Manual, Rule 22
Summary: At the October 2025 meeting of the Arbitration and Rules Committee, a proposal to revise Field Manual Rule 22 was reviewed and approved. Comments are solicited in accordance with Rule 123 and should be sent within 30 days for consideration.
Date: 2025-10-22
C-14640
Subject: Solicitation of Comments, Revisions to Field Manual, Rule 8, Slack Adjusters
Summary: At the October 2025 meeting of the Arbitration and Rules Committee, a proposal to revise Field Manual Rule 8 was reviewed and approved. The circular details the proposed new rules and codes related to slack adjusters and solicits comments within 30 days for consideration.
Date: 2025-10-23
C-14641
Subject: Solicitation of Comments for Cancellation of Circular OT-36-I, Code of Trailer and Container Service and Reporting Rules
Summary: This circular letter solicits comments for the cancellation of Circular OT-36-I. The Intermodal Committee has determined the instructions are no longer applicable and plans to cancel it on February 1, 2026.
Date: 2025-10-23
C-14643
Subject: Solicitation of Comments for Revisions to AAR Intermodal Interchange Rules, Appendix F, Standardize the Why Made Descriptions
Summary: This circular letter solicits comments for proposed revisions to AAR Intermodal Interchange Rules, Appendix F, to standardize the Why Made Descriptions.
Date: 2025-10-23
C-14644
Subject: Solicitation of Comments, Revisions to Field Manual, Rules 3 and 6
Summary: Proposal to revise Field Manual Rules 3 and 6, adding figure references, new graphics, new end hose arrangements, and coupler attached brackets to the correct repair charts.
Date: 2025-10-24
C-14645
Subject: Solicitation of Comments, Revisions to Field Manual, Rule 12, Brake Shoes
Summary: Proposal to revise Field Manual Rule 12, adding a new conditionally approved shoe, combining certain brake shoe types, and adding color to descriptions.
Date: 2025-10-24
C-14646
Subject: Solicitation of Comments, Revisions to Field Manual, Rules 16, 17, 18, 57, and 83, Coupler Carrier Wear Plates
Summary: Proposal to revise Field Manual Rules for coupler carrier wear plates, including correct repair charts, job codes, and why made codes.
Date: 2025-10-24
C-14647
Subject: Solicitation of Comments, Revisions to Field Manual, Rule 82, and Field and Office Manuals Appendix A, Welding and Allied Processes
Summary: Proposal to revise welding and allied processes rules, including precautions, procedures, and qualifications of welders.
Date: 2025-10-24
C-14648
Subject: Solicitation of Comments, Revisions to Field Manual, New Rule 86, Remote Monitoring Equipment
Summary: Proposal to add a new Field Manual Rule 86 for Remote Monitoring Equipment.
Date: 2025-10-24
C-14649
Subject: Solicitation of Comments, Revisions to Field Manual, Rule 92, Transfer or Adjustment of Lading Between Carriers
Summary: Proposal to revise Field Manual Rule 92.
Date: 2025-10-24
C-14650
Subject: Solicitation of Comments, Revisions to Field Manual, Rule 59, Pocket Groups 7F and 9F
Summary: Proposal to revise job codes for Pocket Group 7F and 9F.
Date: 2025-10-24
C-14651
Subject: Solicitation of Comments, Revisions to Field Manual, Rule 95.A, Handling Line Responsibility
Summary: Proposal to reformat Rule 95.A and remove references in other rules.
Date: 2025-10-24
C-14652
Subject: Solicitation of Comments for Revisions to MSRP Section B FREIGHT CAR DRAFT COMPONENTS, New Standard S-122 Cushion Unit Shaft Retainer
Summary: Solicits comments for new standard covering cushion unit shaft retainer geometry and tolerances.
Date: 2025-10-26
C-14656
Subject: Solicitation of Comments, Revisions to Field Manual, Rules 36, 41, 43, 44, 83, Welding Arc Damage
Summary: Proposal to revise rules related to welding arc damage and associated job codes.
Date: 2025-10-29
C-14659
Subject: Solicitation of Comments, Revisions to Field Manual, Rules 36, 37, 41, 43, and 44
Summary: Proposal to update SCRAP requirements due to fire or heat damage to wheel set components.
Date: 2025-10-29
C-14661
Subject: Solicitation of Comments for Revisions to MSRP Section C CAR CONSTRUCTION FUNDAMENTALS AND DETAILS, new Specification M-802 Manufacturer of Freight Cars
Summary: Solicits comments for new specification replacing Standard S-2034 Car Builder Certification.
Date: 2025-10-29
C-14662
Subject: Solicitation of Comments, Revisions to Field Manual, Rules 89, 90 and Various Related Rules
Summary: Proposal to revise rules 89, 90 and related rules.
Date: 2025-10-29
C-14665
Subject: Solicitation of Comments, Revisions to Office Manual, Rules 107 & 111, Rack Only Incidents
Summary: Proposal to revise Office Manual Rules 107 & 111 for billing destroyed superstructure and dismantled units.
Date: 2025-10-30
Notice of Circulars
C-14623
Subject: Car Repair Billing Data Exchange Schedule – Effective January 1, 2026
Summary: The circular provides details about the Car Repair Billing Data Exchange (CRBDX) maintained by Railinc, which is a monthly exchange of repair bills for foreign freight equipment. It outlines the schedule for inbound and outbound dates for repair bills starting January 1, 2025, and includes a 2026 schedule for these dates.
Date: 2025-10-08
Effective Date: 2026-01-01
C-14625
Subject: Informational Circular, AAR Field Manual Appendix D Update – October 1, 2025
Summary: Appendix D of the Association of American Railroads (AAR) Field Manual has been updated and is now available on the Railinc website. The appendix provides a listing of job codes and data elements used for repairs to Tank Cars and Covered Hopper Cars not included in standard AAR job codes, aiming to provide uniform and accurate data reporting for estimating, billing, auditing, and analysis.
Date: 2025-10-09
Effective Date: 2025-10-01
C-14666
Subject: Informational Circular, Revisions to Office Manual Rule 114.12, Contact Maintenance
Summary: Clarifies that the reporting mark owner is responsible for maintaining accurate contact information in FindUs.Rail.
Date: 2025-10-30
Effective Date: 2025-10-30
C-14667
Subject: Informational Circular, Revisions to Office Manual Rule Appendix B, Form SE-3
Summary: Revision to Office Manual Appendix B to be included in the January 1, 2026 release.
Date: 2025-10-30
Effective Date: 2026-01-01
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