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-14421
AAR Manual of Standards and Recommended Practices (MSRP), Section K-V Electronics Environmental Requirements and Systems Management, Standard S-9452.V3.1
Issued: October 7, 2024
Effective: October 7, 2024
ITC Systems Management (ITCSM) produces specifications for how the systems management infrastructure should be built, for what all ITC Asset types should support, and for what each individual ITC Asset type should support. S-9452.V3.1was Adopted in 2012 and Last Revised in 2024 and is attached to this circular in PDF format. S-9452.V3.1 will be incorporated into the next issue of the MSRP Section K-V Electronics Environmental Requirements and Systems Management. In the interim, please insert the Circular in your copy of the MSRP Section K-V and be governed accordingly.
C-14424
MSRP Section S-III, COUPLER AND YOKE DETAILS, Standards S-102, S-103, and S-163, regarding MSRP references and coupler butt dimensions and tolerances for E60EE, SBE60EE, and SE60EE couplers
Issued: October 9, 2024
Effective: October 9, 2024
The purpose of this circular letter is to notify the industry of revisions to Section S-III, COUPLER AND YOKE DETAILS, Standards:
- S-102: Coupler, E Type, E60EE
- S-103: Coupler, E Type, Top and Bottom Shelf, SE60EE
- S-163: Coupler, E Type, Bottom Shelf, SBE60EE
On August 7, 2024, Circular Letter C-14409 was issued to solicit comments. Comments were received and reviewed by the Coupling System and Truck Castings Committee (CSTCC). No changes were recommended, and no changes were made in response to the comments received. Standards S-102, S-103, and S-163 are now implemented and effective immediately. This modification will be incorporated in the next issue of the Manual of Standards and Recommended Practices, Section S-III. Please update your library and be governed accordingly.
C-14426
MSRP F, Sensors, S-6101 –Detector Calibration & Validation Requirements / ABD Site Current Validations
Issued: October 17, 2024
Effective: October 17, 2024
This implementation circular is being released to the industry for revisions to the AAR’s Manual of Standards & Recommended Practices (MSRP) Section F – Sensors / Detector Calibration & Validation Requirements / ABD Site Current Validations. AAR’s Equipment Health Monitoring Committee (EHMC) voted to progress the standard to implementation upon WABL Committee’s recommendation. The implemented standard is attached as reference.
C-14431
MSRP Section S-III, COUPLER AND YOKE DETAILS, Standard S-103, Coupler E Type Top and Bottom Shelf SE60EE, Restoring missing text
Issued: October 24, 2024
Effective: October 24, 2024
The purpose of this circular letter is to notify the industry of editorial revisions to MSRP Section S-III, COUPLER AND YOKE DETAILS, Standard S-103, Coupler E Type Top and Bottom Shelf SE60EE, to restore missing text above the notes section. The revised Standard S-103 is now implemented and effective immediately. This modification will be incorporated in the next issue of the Manual of Standards and Recommended Practices, Section S-III. Please update your library and be governed accordingly.
C-14443
MSRP Section D, TRUCKS AND TRUCK DETAILS, 2024
Issued: October 25, 2024
Effective: October 25, 2024
The Association of American Railroads Equipment Engineering Committee is pleased to announce a new edition of the Manual of Standards and Recommended Practices, Section D, TRUCKS AND TRUCK DETAILS.
The revised MSRP Section D is now available in both printed and electronic versions. Current pricing is available online at www.aarpublications.com where the manual can be purchased.
All previously implemented standards and specifications are included in this print of Section D. Please update your library and be governed accordingly.
C-14444
MSRP, Section M, LOCOMOTIVES AND LOCOMOTIVE INTERCHANGE EQUIPMENT: Recommended Practice RP-509 – BRAKING RATIOS FOR LOCOMOTIVES
Issued: October 28, 2024
Effective: October 28, 2024
The purpose of this circular letter is to notify the industry of revisions to the Manual of Standards and Recommended Practices (MSRP) – Section M, LOCOMOTIVE INTERCHANGE EQUIPMENT, Recommended Practice: RP-509 – BRAKING RATIOS FOR LOCOMOTIVES.
The revised RP-509 is hereby implemented and effective immediately. A copy is attached to this circular for your reference.
The revised RP-509 will be reflected in the next issue of Section M. In the interim, please insert this circular into your copy of MSRP Section M and be governed accordingly.
C-14446
Office Manual Rule 112.E, Time Limits for Invoicing
Issued: October 28, 2024
Effective: January 1, 2025
At the September 2024 meeting of the Arbitration and Rules Committee, a proposal advanced by the Car Billing Repair Committee to revise Office Manual Rule 112.E was reviewed and approved. The entire text of the revision is included as an attachment to this Circular Letter.
These changes will be included in the January 1, 2025 release of the Office Manual.
C-14447
Office Manual Rule 112.H.4, Required Exceptions Format
Issued: October 28, 2024
Effective: January 1, 2025
At the September 2024 meeting of the Arbitration and Rules Committee, a proposal as advanced by the Car Repair Committee to revise Office Manual Rule 112.H.4, was reviewed and approved. The entire text of the revision is identified in the circular letter.
These changes will be included in the January 1, 2025 release of the Office Manual.
Call for Comment
C-14423
DRAFT S-9170.V1.0 Precision Navigation Module (PNM) Specification, in support of AAR’s MSRP – Section K-II Locomotive Electronics and Train Control System Architecture
Issued: October 7, 2024
Effective: 30 days for comment.
The Railroad Electronics Standards Committee (RESC) of the Association of American Railroads (AAR) is publishing DRAFT S-9170.V1.0 Precision Navigation Module (PNM) Specification for review and comment. This specification applies to the Precision Navigation Module (PNM). The PNM is intended to be the primary source of navigation information for all locomotive onboard systems. This specification contains the interoperable functional and non-functional requirements for PNMs.
See circular for instructions on how to review and comment on this draft.
C-14422
DRAFT S-9152.V3.0 End-Of-Train Communications, in support of AAR’s MSRP – Section K-II Locomotive Electronics and Train Consist System Architecture
Issued: October 7, 2024
Effective: 30 days for comment.
The Wireless Communication Committee (WCC) of the Association of American Railroads (AAR) is publishing DRAFT S-9152.V3.0 End-Of-Train Communication for review and comment. This document presents the standard for train information systems, intended to provide additional train handling and safety information in locomotive cabs.
See circular for instructions on how to review and comment on this draft.
C-14425
MSRP Section S, CASTING DETAILS, Specification M-214, Side Frames and Bolsters, Used and Reconditioned – Classification and Repair Procedure, regarding Increased Component Life (ICL) and other requirements
Issued: October 14, 2024
Effective: 30 days for comment.
The purpose of this circular letter is to solicit comments for revisions proposed to Section S, Specification M-214, Side Frames and Bolsters, Used and Reconditioned – Classification and Repair Procedure, regarding updating Increased Component Life (ICL) eligibility requirements, dimension and tolerance of bolster top extension width, and reconditioning of wear plate securement back face surface.
Changes are highlighted with change bars in the file attached to the circular.
C-14430
MSRP Section S-III, COUPLER AND YOKE DETAILS, Standards S-107, S-154, and S-164, regarding MSRP references and coupler butt dimensions and tolerances for E67DE, SBE67DE, and SE67DE couplers
Issued: October 24, 2024
Effective: 30 days for comment.
The purpose of this circular letter is to solicit comments for revisions proposed to Section S-III, Standards:
- S-107: Coupler, E Type, E67DE
- S-154: Coupler, E Type, Top and Bottom Shelf, SE67DE
- S-164: Coupler, E Type, Bottom Shelf, SBE67DE
The AAR Coupling System and Truck Castings Committee (CSTCC) is proposing the following revisions:
- Improved image quality
- Added butt dimensions and tolerances
- Added references to Standards S-106 and S-173
- Added references to M-211 and M-215 for technical approval requirements
- Added a note that dimensions without tolerances are to be treated as reference dimensions
Changes are highlighted with change bars in the files attached to the circular.
C-14442
Office Manual, Rule 88.C.3 Minimum Requirements Chart
Issued: October 25, 2024
Effective: 30 days for comment.
At the September 2024 meeting of the Arbitration and Rules Committee, a proposal as advanced by the Equipment Engineering Committee to revise Office Manual Rule 88, was reviewed and approved.
The entire text of the revision is identified in the circular letter.
C-14441
Field Manual, Rules B, 15-20, 47, 48, and 95, and Office Manual Rule B
Issued: October 25, 2024
Effective: 30 days for comment.
At the September 2024 meeting of the Arbitration and Rules Committee, a proposal as advanced by the Coupling Systems and Truck Castings Committee to revise Field Manual Rules B, 15-20, 47, 48 and 95, and Office Manual Rule B, to include clarification on handling of heat/fire damaged components, was reviewed and approved.
The entire text of the revision is identified in the circular letter.
C-14440
Field Manual, Rule 48
Issued: October 25, 2024
Effective: 30 days for comment.
At the September 2024 meeting of the Arbitration and Rules Committee, a proposal as advanced by the Coupling Systems and Truck Castings Committee to revise Field Manual Rule 48 regarding Why Made Code usage, was reviewed and approved.
The entire text of the revision is identified in the circular letter.
C-14439
Field Manual, Rule 96.C and Rule 108.7
Issued: October 25, 2024
Effective: 30 days for comment.
At the May 2024 meeting of the Arbitration and Rules Committee, a proposal to revise Field Manual Rule 96 and Rule 108, was reviewed and approved.
The entire text of the revision is identified in the circular letter.
C-14438
Field Manual, Rule 90.B.4 and Rule 91.2.h
Issued: October 25, 2024
Effective: 30 days for comment.
At the October 2024 meeting of the Arbitration and Rules Committee, a proposal to revise Field Manual Rule 90 to prohibit bearings with EHMS HBD_TRND alerts in interchange service, was reviewed and approved.
The entire text of the revision is identified in the circular letter.
EHMS HBD_TRND alert, is a new alert that has a planned implementation date in Q1, 2025. The alert will identify cars with bearings meeting the criteria in MSRP F, S-6001, Section 4.1.3 (see circular C-14282, issued November 29, 2023).
C-14437
Field Manual, Rule 88.B.4, Roller Bearing Cap Screw Seal Rings
Issued: October 25, 2024
Effective: 30 days for comment.
At the September 2024 meeting of the Arbitration and Rules Committee, a proposal as advanced by the WABL Committee to revise Field Manual Rule 88, to remove 88.B.4, was reviewed and approved.
The entire text of the revision is identified in the circular letter.
C-14436
Field Manual, Rule 41 and Rule 83, Slid Flat
Issued: October 25, 2024
Effective: 30 days for comment.
At the September 2024 meeting of the Arbitration and Rules Committee, a proposal as advanced by the Car Repair Billing Committee to revise Field Manual Rules 41 and 83, was reviewed and approved.
The entire text of the revision is identified in the circular letter.
C-14435
Field Manual, Rule 36.E.11, Why Made Code 50
Issued: October 25, 2024
Effective: 30 days for comment.
At the September 2024 meeting of the Arbitration and Rules Committee, a proposal as advanced by the WABL Committee to revise Field Manual Rule 36.E.11, was reviewed and approved.
The entire text of the revision is identified in the circular letter.
C-14434
Field Manual, Rules 16.D, 17.D and 18.D, Welding
Issued: October 25, 2024
Effective: 30 days for comment.
At the September 2024 meeting of the Arbitration and Rules Committee, a proposal as advanced by the Coupling Systems and Truck Castings Committee to revise Field Manual Rules 16, 17 and 18, to address welding of coupler carrier wearplate and wearplate shims, was reviewed and approved.
The entire text of the revision is identified in the circular letter.
C-14433
Field Manual, Rule 36.E.11, Why Made Code 50
Issued: October 25, 2024
Effective: 30 days for comment.
At the September 2024 meeting of the Arbitration and Rules Committee, a proposal as advanced by the Coupling Systems and Truck Castings Committee to revise Field Manual Rule 15, to address worn out Retainer Keys, was reviewed and approved.
The entire text of the revision is identified in the circular letter.
C-14432
Field Manual, Rule 9
Issued: October 25, 2024
Effective: 30 days for comment.
A At the September 2024 meeting of the Arbitration and Rules Committee, a proposal as advanced by the Car Repair Billing Committee to revise Field Manual Rule 9 for Job Code 1432, was reviewed and approved.
The entire text of the revision is identified in the circular letter.
C-14445
Office Manual, Rules 112 and Rule 114
Issued: October 28, 2024
Effective: 30 days for comment.
At the September 2024 meeting of the Arbitration and Rules Committee, a proposal as advanced by the Car Repair Billing Committee to revise Office Manual Rules 112 and 114 was reviewed and approved.
The entire text of the revision is identified in the circular letter.
C-14450
Field and Office Manuals, Various Rules Related to Tank Cars
Issued: October 29, 2024
Effective: 30 days for comment.
At the September 2024 meeting of the Arbitration and Rules Committee, a proposal as advanced by the Equipment Engineering Committee and the Tank Car Committee to revise various Field and Office Manual Rules for general clean-up and to align with M-1002, was reviewed and approved.
The entire text of the revision is identified in the circular letter.
C-14449
Field Manual, Rule 108
Issued: October 29, 2024
Effective: 30 days for comment.
At the September 2024 meeting of the Arbitration and Rules Committee, a proposal to revise Field Manual Rule 108, to add requirement to provide pictures and reformat for clarification and to align with the DDCT system, was reviewed and approved.
The entire text of the revision is identified in the circular letter.
C-14448
Field Manual, Rule 47
Issued: October 29, 2024
Effective: 30 days for comment.
At the September 2024 meeting of the Arbitration and Rules Committee, a proposal as advanced by the Coupling Systems and Truck Castings Committee to revise Field Manual Rule 47 regarding Why Made Code usage, was reviewed and approved.
The entire text of the revision is identified in the circular letter.
C-14452
MSRP Section C, CAR CONSTRUCTION FUNDAMENTALS AND DETAILS, Standard S-252 Door Air Lines – Location of End Cocks, retirement of plate figures
Issued: October 31, 2024
Effective: 30 days for comment.
The purpose of this circular letter is to solicit comments for revisions proposed to Section C, CAR CONSTRUCTION FUNDAMENTALS AND DETAILS, Standard S-252 Door Air Lines – Location of End Cocks. The AAR Equipment Engineering Committee (EEC) is proposing the following changes:
- Change the title from “Door Air Lines – Location of End Cocks” to “Auxiliary Air Train Line.”
- Change “door air line system” to “auxiliary air train line” where it appears on figure captions.
- Delete plates No. I, II, and VI, and renumber the remaining plates in the order they appear.
Attached to the circular are the current standard with edits shown in Adobe, along with the proposed revision.
C-14451
MSRP Section C, CAR CONSTRUCTION FUNDAMENTALS AND DETAILS, Standard S-2045 Remote Monitoring Equipment Installation, revision of requirements
Issued: October 31, 2024
Effective: 30 days for comment.
The purpose of this circular letter is to solicit comments for revisions proposed to Section C, CAR CONSTRUCTION FUNDAMENTALS AND DETAILS, Standard S-2045 Remote Monitoring Equipment, Installation. The standard is being edited for three purposes:
- To include in paragraph 1.4 components with embedded remote monitoring equipment.
- To add a new paragraph 1.5 that sets forth requirements for components with embedded remote monitoring equipment.
- To correct the language used in paragraph 3.1 relative to nonincendive electrical equipment.
Proposed Standard S-2045 is attached to the circular.
Notice of Circulars
C-14427
Revisions to CRB Procedures Manual, New Error Codes 8S, 8U, & 1Z
Issued: October 18, 2024
Effective: January 2025
IMPORTANT NOTE: It is recommended that this information be shared with all Car Repair Billing and IT personnel in your company that work with or are responsible for car repair invoices submitted to and/or received from Railinc’s Car Repair Billing Data Exchange.
At the September 2024 meeting of the Car Repair Billing Committee, two proposals to implement new CRB Repair Billing Data Exchange (CRBDX) error codes were approved. These error codes will be implemented as informational edits immediately after the January 2025 Data Exchange run. Edits 8S & 8U will be rolled into 8P & 8R respectively and 1Z will become a mandatory reject after the July 2025 Data Exchange run.
C-14429
Rescinding Circular C-14374 published on May 20, 2024, itemizing OTLR Requirements for Containers on Flatcars or Articulated Flatcars in Manifest Train Service
Issued: October 21, 2024
Effective: October 21, 2024
The Open Top Loading Rules (OTLR) Committee of the Association of American Railroads (AAR) has rescinded Circular C-14374. C-14374 was published on May 20, 2024 to call attention to OTLR concerns with new business opportunities to transport containers on flatcars or articulated flatcars in manifest train service. Of particular concern were shipments of Lithium-ion batteries and shipments of dense materials such as metallic concentrates.
However, C-14374 included reference to legacy shipments with a historical precedence of effective securement. Numerous car owners raised their unease with C-14734, asserting their long history of moving legacy commodities safely. Subsequently, the OTLR was asked to rescind or modify C-14374. Other AAR committees were asked for input. The Equipment Engineering Committee (EEC) held discussions on the matter during their August and September 2024 meetings and recommended C-14374 be rescinded while the rules between the OTLR and intermodal requirements are investigated. The Intermodal Committee (IC) was also asked for input.
A Technical Advisory Group (TAG) is being formed to investigate and provide guidance on the use of containers on flat cars; The EEC will take the lead and involve the IC, OTLR, other committees and/or individuals as appropriate.
Upcoming Event
2025 AAR M-1003 Quality Assurance Auditor Training Class Schedule and Registration
The Association of American Railroads (AAR) Quality Assurance Committee (QAC) is pleased to announce the schedule for 2025 AAR M-1003 Quality Assurance Training classes.
Who Should Attend?
- Any individual requiring a working knowledge and understanding of the M-1003 Specification
- Quality Professionals/Consultants
- Quality Managers, Supervisors, Inspectors
- Internal & Supplier/Vendor Auditors
- Organizations seeking to provide product for use in AAR Interchange
See Circular C-14428 for full schedule, class descriptions, and registration links.
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