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-14789
Subject: Implementation of 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, regarding the addition of a new pocket, EMS-4
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. A detailed drawing and reference table of an additional EMS pocket, EMS-4 (STRATO SC-5210 DRAFT PACK WITH SC-2019 BUFF PACK), have been added.
Date: 05-19-2026
Effective Date: 05-19-2026
Call for Comment
C-14787
Subject: Solicitation of Comments, Revisions to Office Manual Rule 112, Correcting and Resubmitting Invoices
Summary: In May 2026, the Arbitration and Rules Committee reviewed and approved a proposal to revise Office Manual Rule 112. The revision includes changes to the procedures for correcting and resubmitting rejected invoices in accordance with the Car Repair Billing Procedures Manual.
Date: 05-05-2026
Comment Period: 30 Days
C-14788
Subject: Soliciting Non-Class I Railroad & Running Repair Agent Participants for Inclusion in the 2027 CRB Survey Process
Summary: This circular solicits Non-Class I Railroad and Running Repair Agent participants for inclusion in the 2027 Car Repair Billing (CRB) survey process. It outlines the deadlines for submitting data for the Base Wage Rate Survey, Overhead Study Survey, and Material Price Survey, and requests interested companies to complete the attached contact form and notify the AAR by June 15, 2026.
Date: 05-13-2026
Comment Period: Until June 15, 2026
C-14790
Subject: Solicitation of Comments, Revision to Field Manual, Rule 83.16, Mechanical Refrigeration Car Part Codes
Summary: This circular announces a solicitation of comments regarding revisions to Field Manual Rule 83.16 related to Mechanical Refrigeration Car Part Codes. It details the proposed changes and notes that car part codes removed from the Field Manual will be retired from usage in the Car Repair Billing application effective January 1, 2027.
Date: 05-22-2026
Comment Period: 30 Days
Notice of Circulars
C-14792
Subject: Informational Circular, Revisions to Field Manual Rules 4, 8 and 89
Summary: At the April 2026 meeting of the Arbitration and Rules Committee, a proposal as advanced by the Brake Systems Committee to revise Field Manual Rule 4.B.13 to address cars destined for scrap, was reviewed and approved. Additionally, Rules 8 and 89 have been editorially updated for consistency. The entire text of the revision is identified in the Circular.
Date: 05-29-2026
Effective Date: 05-29-2026
C-14793
Subject: Informational Circular, Revisions to Field Manual Rule 4.E.20, 4-Pressure Gasket Application
Summary: At the April 2026 meeting of the Arbitration and Rules Committee, a proposal to revise Field Manual Rule 4.E.20 to clarify application of 4-pressure gaskets, specifically the dust cover plate gasket, was reviewed and approved. The revision includes replacement requirements for rubber parts and clarifies that replacement of the 4-pressure receiver’s dust cover plate gasket(s) is not required at the time of single car air brake test.
Date: 05-29-2026
Effective Date: 05-29-2026
C-14794
Subject: Informational Circular, Revisions to Field Manual Rule 12.A.1, Brake Shoes and Shoe Keys
Summary: At the April 2026 meeting of the Arbitration and Rules Committee, a proposal as advanced by the Brake Systems Committee to revise Field Manual Rule 12.A.1 was reviewed and approved. The entire text of the revision is identified in the Circular, including causes for attention related to brake shoes, and this change will be included in the July 1, 2026 updates to the Field Manual.
Date: 05-29-2026
Effective Date: 07-01-2026
C-14795
Subject: Informational Circular, Revisions to Field Manual Rule 12, Brake Shoes and Shoe Keys
Summary: At the April 2026 meeting of the Arbitration and Rules Committee, a proposal as advanced by the Brake Systems Committee to revise Field Manual Rule 12 to add new Figure 12.5, was reviewed and approved. The entire text of the revision is identified in the Circular, and this change will be included in the July 1, 2026 updates to the Field Manual.
Date: 05-29-2026
Effective Date: 07-01-2026
CPC-1445
Subject: Extended Timeline on Service Trial 429- Vacuum Relief Valve (A-210, A-211, A-212)
Summary: At the October 2025 TCC meeting, the Tank Car Committee voted to cancel service trial 429 because it did not complete service trial requirements, subsequently a CPC was published in November of 2025. At the April 2026 TCC Meeting, the Tank Car Committee revisited the matter and voted to extend the timeline for the removal and replacement of units in service from within 3 years to within 5 years or next shopping at a facility capable of removing and replacing the valves; not to exceed next qualification cycle of the tank.
Date: 05-18-2026
Effective Date: 05-18-2026
MARS Meeting
The Greenbrier Companies is a Proud Sponsor
July 13-14 | Lake Geneva, WI
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)
Greenbrier Management Services (GMS) is North America’s most comprehensive railcar management solutions provider. GMS manages nearly 400,000 railcars and has invested over 20 years in developing technology, processes, and people to provide the best railcar management products and services in the industry. GMS is powered by proprietary software and the best subject matter experts in the railcar business.
COMPREHENSIVE. INTEGRATED. VALUE.
Combined, these two vitally important capabilities are able to deliver world-class solutions to every type of customer, from Class I railroads, lessors and industrial shippers to financial investors. GMS brings broad expertise to cover nearly any railcar management need that customers may have and its integrated solutions and reporting can be customized for any customer function or management need.