§393.201 requires that the frame and frame assemblies on a CMV not be cracked, loose, sagging, or broken. The rule also addresses welded or bolted frame repairs — repairs that do not restore the frame to original strength produce findings whether or not the original break is visible.
Severity weight + OOS
Severity weight 5 in the Vehicle Maintenance BASIC. A crack through a frame side rail, a broken cross-member tied to a primary load path, or a frame loose at the body mount is an OOS condition. The failure mode is catastrophic — a separated frame ends the trip and often the vehicle.
How it gets cited
The two patterns: (1) cracks at known stress concentrations — behind the steer-axle mounts, at the fifth-wheel mounting plate, at suspension hangers; (2) prior repairs that show progressive cracking around the weld bead because the repair did not address the underlying cause (a chronic overload, a missing reinforcement plate, a poor weld procedure).
How to prevent it
- Annual §396.17 inspection must include a frame visual from underneath, both rails end-to-end, both sides.
- Treat any new crack as a §396.9(d)(3) hard fail — the vehicle does not move until a qualified welder restores it per the OEM's frame-repair procedure.
- For chronic-crack vehicles, address the cause (loading pattern, suspension travel, weight distribution), not just the symptom.
How Roadworthy HQ helps
§393.201 findings trigger a critical-severity alert and route through the §396.9(d)(3) repair certification before the vehicle returns to service — the repair procedure, the welder qualification, and the post-repair inspection live together in the audit binder.