§393.48 is the foundational brake-condition rule: all brakes with which a CMV is equipped, including those of any towed vehicle, must be operative at all times. The rule sits behind §393.47 (adjustment), §393.52 (performance), and the §393.42–§393.46 design requirements — a brake that fails any of these is also "inoperative" under §393.48.
OOS
A brake counts toward the 20% OOS threshold if it is missing, broken, disconnected, contaminated with oil or grease, or otherwise inoperative. When 20% or more of the brakes on the vehicle are defective, the vehicle is OOS under the NAS Out-of-Service Criteria.
Severity weight
Severity weight 4 in the Vehicle Maintenance BASIC. The weight rises when a §393.48 finding is cited together with §393.47 (out of adjustment) and §393.52 (performance) — the cluster, not the single weight, is what moves the percentile.
How to prevent it
- Treat any oil- or grease-contaminated brake as inoperative — the seal failure usually predates the contamination.
- Replace shoes and drums together when wear is uneven; preserve the wheel-end as a unit.
- A disconnected air line, kinked hose, or stuck push rod all count as "inoperative" — pre-trip air-brake test catches most of these.
How Roadworthy HQ helps
An inoperative-brake citation shows up in Roadworthy HQ as part of the inspection it came from, not as a record of its own: the app does not store individual violation codes. Log the roadside inspection on the vehicle's Inspections tab: date, state, level, driver, the number of violations, and whether it was out-of-service. For an out-of-service inspection the 15-day §396.9(d)(3) repair-certification countdown stays on that tab until you enter the certification date. The rule's 15 days cover every violation on the report, not only out-of-service ones, so for a non-OOS inspection that date is yours to track. The repair itself goes in the vehicle's maintenance log: date, type, what was done, who did it, and cost. DVIRs are logged per vehicle with the defect described in your own words, and a defect marked safety-affecting that is logged without a repair certification sends a critical alert. The §396.17 annual inspection report uploads to the vehicle, with reminders 60, 30, and 7 days before the next one is due.