What 393.50(a) means in plain language
When you receive a citation for 393.50(a), the inspector found that your vehicle's steering mechanism was defective, broken, or not functioning properly. This is a straightforward safety violation: if the steering system isn't working as designed, you cannot safely control the vehicle on the road.
The steering mechanism includes the steering wheel, steering column, tie rods, steering gearbox, and all linkages that connect driver input to wheel direction. A defective steering system means any of these components shows excessive play, binding, looseness, or damage that prevents normal, responsive steering. Inspectors test this by checking for slack in the wheel, unusual resistance, or visible damage to components.
This violation is about mechanical condition, not paperwork or maintenance records. The inspector confirmed through a hands-on check that something in your steering system wasn't safe.
What our enforcement data actually shows
Across our 13 million+ inspection records, 393.50(a) has been cited 32 times total. In the last 12 months, we recorded zero citations, and in the last 90 days, zero citations—making this an extremely rare violation in the current enforcement landscape.
When 393.50(a) citations have been issued, inspectors placed the vehicle out of service in 50.0% of those cases. This is notably higher than the all-FMCSR average out-of-service rate of 31.4%, meaning that when steering defects are found, they tend to be serious enough to remove the vehicle from service more often than average violations do.
Nationally, 393.50(a) ranks #1775 out of 3,036 FMCSR codes by citation volume, placing it in the lower-frequency end of enforcement activity. The rarity of recent citations suggests that most commercial operators are maintaining steering systems effectively, and inspectors are encountering this defect infrequently.
Who gets cited most
Our inspection records show that top carriers cited for 393.50(a) include Lonergans Charter Service Inc (USDOT 84782), Globe Trucking Inc (USDOT 198473), and Koster Grain Inc (USDOT 322384), each with one citation across the record set. The distribution is extremely dispersed—no single carrier dominates, and all citations are isolated incidents rather than patterns.
Vehicle makes cited most frequently are Kenworth (KW) and Freightliner (FRHT), each with 3 citations. International (INTL) and Mack (MACK) trucks each appear in 2 citations. This spread across major manufacturers suggests that steering defects occur across all truck types and are not specific to any one brand's engineering or design.
How severe is this compared to similar codes
Within the vehicle maintenance category, steering mechanism defects sit on a distinct enforcement spectrum. Compare 393.50(a) to its closest peers:
- 393.9(a) — Inoperable required lamps has been cited 660,737 times with a 15.4% out-of-service rate. Lighting violations are far more common but less likely to result in immediate removal.
- 396.3(a)(1) — Inspection/repair/maintenance general shows 236,919 citations with a 45.3% out-of-service rate, slightly exceeding 393.50(a)'s 50.0% rate and indicating that general maintenance defects are cited far more often but removed at comparable or lower severity.
- 393.78 — Windshield condition defective has 157,894 citations with only a 0.3% out-of-service rate, demonstrating that cosmetic or minor visibility issues are extremely common but rarely warrant removal from service.
The high out-of-service rate for steering defects (50.0%) underscores that steering system failures are treated as immediately hazardous—matching or exceeding other structural safety issues.
How to avoid it
Steering system maintenance is a core pre-trip responsibility. Use these concrete checks before every departure:
-
Test the steering wheel for slack. Grasp the steering wheel at three and nine o'clock and gently rock it side to side. Excessive movement (more than one or two inches) indicates worn tie-rod ends, steering gearbox play, or worn steering column bearings. Stop and have it inspected if you feel significant play.
-
Feel for binding or resistance. Turn the steering wheel fully left and fully right while the truck is parked. Movement should be smooth and even. If you detect grinding, clicking, catching, or unusual resistance, the steering column or linkage may be damaged. Do not operate the vehicle until the defect is corrected.
-
Inspect under the truck for visible damage. Look for bent tie rods, cracked steering arms, loose bolts on the steering gearbox mounting, or evidence of previous impact damage. Steering components take direct hits during rough road conditions and tight maneuvers; visible cracks or bends are failure warnings.
-
Check the power steering fluid (if equipped). Low or contaminated fluid can cause steering stiffness, response delay, or groaning sounds. Top up or flush as needed per manufacturer spec. Leaking seals at the steering pump, hoses, or gearbox are precursors to complete failure.
-
Listen for steering-related noises. Knocking, popping, or squealing while turning suggests worn joints, dry steering bushings, or belt slippage in the power steering pump. Do not ignore these as warning signs; they often precede mechanical failure.
-
Verify steering works before departure. Do a slow, controlled test in an empty lot or parking area. Confirm that the steering responds immediately to input and that all four wheels track correctly. If you notice pull to one side, delayed response, or stiffness that worsens with turning angle, have a certified technician inspect before road operation.
Because steering defects directly affect your ability to control the truck in emergency maneuvers, weather, or traffic, these checks are not optional. The 50.0% out-of-service rate for this violation reflects the serious safety hazard—inspectors will not hesitate to strand your vehicle if steering is compromised.