What 393.44 means in plain language
FMCSR 393.44 requires that buses have properly functioning protection on their front brake lines. The regulation exists because brake lines on the front of a bus are exposed to road hazards—rocks, debris, road salt, and impact from potholes or collisions can damage them, leading to brake failure.
The "protection" typically means guards, clips, or routing that keeps brake lines away from damage. If an inspector finds that your bus is missing this protection entirely, or that existing guards are cracked, loose, or ineffective, you'll be cited. The violation isn't about whether your brakes work; it's about whether the lines themselves are shielded from harm.
This applies to buses specifically—not to other truck classes. The intent is straightforward: prevent preventable brake-system failures caused by external damage to brake lines.
What our enforcement data actually shows
Across our 13 million+ roadside inspection records, 393.44 is an exceptionally rare citation. All-time, we've recorded just 1 citation for this code. In the last 12 months, there have been 0 citations, and in the last 90 days, also 0 citations.
The single citation on record was not placed out-of-service, meaning the inspector allowed the vehicle to continue operating. This 0.0% out-of-service rate is well below the all-FMCSR average of 31.4%, though the tiny sample size limits what we can conclude from that comparison.
Nationally, 393.44 ranks #2796 out of 3,036 FMCSR codes by citation volume. In practical terms: this violation almost never shows up in roadside enforcement. If you've been cited for it, you're in a very small group.
Who gets cited most
Our database shows just one citation for 393.44 all-time. That citation was issued to a vehicle registered to SUNDAY RIVER SKIWAY CORPORATION (USDOT 754722), a bus operator. The vehicle was a GMC. Because enforcement volume is so minimal, we cannot reliably identify state or carrier patterns, and regional comparison data is not available.
If your citation is the first in several years, the rarity of this code means systematic issues with brake-line protection across the industry are not widespread in our inspection data.
How severe is this compared to similar codes
Within the Vehicle Maintenance category, 393.44 sits at the very bottom of enforcement frequency. By contrast:
- 393.9(a) — Inoperable required lamps accounts for 660,737 citations with a 15.4% out-of-service rate. Lighting defects are far more commonly cited and result in OOS decisions at roughly half the all-FMCSR average.
- 396.3(a)(1) — Inspection/repair/maintenance (general) has 236,919 citations and a 45.3% OOS rate, the highest among peer codes and well above the all-FMCSR average, reflecting the severity inspectors assign to systemic maintenance failures.
- 393.47E — Slack adjuster defective shows 180,363 citations but a 0.0% OOS rate, similar to 393.44 in that defective components are cited but vehicles aren't routinely removed from service.
Your 393.44 citation is orders of magnitude rarer than these peers, suggesting it's either caught very infrequently or that brake-line protection failures are genuinely uncommon in the bus fleet.
How to avoid it
Because 393.44 focuses on brake-line integrity and shielding, here are concrete actions you can take:
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Inspect brake lines during your pre-trip walk-around. Look under the front of the bus and trace the brake lines from the master cylinder. Check for any guards, clips, or protective coverings that are loose, cracked, or missing. If guards are present but rattling or damaged, they won't protect the lines from impact.
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Check for signs of impact damage. Brake lines can be dented or crimped without being completely severed. A dent that narrows the line's internal diameter can restrict fluid flow. During your walk-around, look for flattened or creased sections of brake tubing or hose.
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Verify routing and clearance. Brake lines should be routed away from hot surfaces (like exhaust), moving parts, and edges that could chafe them. If lines are rubbing against a sharp edge or mounting bracket, they may eventually fail. Move them aside gently during inspection to confirm they have slack and aren't under tension.
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Report defects immediately to your dispatcher or maintenance team. Brake-line protection isn't something a driver can field-repair at the roadside. If you spot a missing guard or damaged line, the vehicle should go to a shop before the next road assignment.
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Understand your vehicle's brake-system design. Some buses route brake lines internally or use integrated brake modules that reduce external exposure. Know whether your bus model has external lines that require guards, or whether the design inherently shields them. Ask your safety manager or trainer during onboarding.