What 393.71 means in plain language
Code 393.71 flags a fifth wheel assembly that is defective, worn excessively, or not properly secured to your commercial motor vehicle. The fifth wheel is the mechanical coupling that connects your tractor to a trailer—it bears enormous stress during turns, braking, and acceleration. If it's worn, cracked, damaged, or loose, it can fail suddenly, potentially detaching the trailer and creating a catastrophic road hazard.
A citation for 393.71 means a roadside inspector found evidence of one or more of these problems: structural cracks or breaks in the fifth wheel casting or mounting bracket, missing or damaged locking pins, excessive vertical or horizontal movement when the inspector applied pressure, rust or corrosion that compromises integrity, or fasteners (bolts, welds) that are loose, missing, or severely corroded. It's not a warning—it's a mechanical defect that regulators consider unsafe to operate.
What our enforcement data actually shows
Across our 13 million+ roadside inspection records, code 393.71 has generated 73 all-time citations, making it rank #1516 out of 3,036 FMCSR codes by frequency. In the last 12 months, we recorded 9 citations; in the last 90 days, 4 citations appeared in our database.
The critical number: 69.9% of 393.71 citations result in an out-of-service order. That means if you're cited for this code, there's a roughly 7-in-10 chance your vehicle will be placed out of service on the spot. For context, the all-FMCSR average OOS rate is 31.4%—so this violation carries nearly 2.2 times the national rate. Of the 73 all-time citations in our records, 51 resulted in an immediate out-of-service placement; 22 did not.
This high OOS rate reflects the severity regulators assign: 393.71 carries a CSA Severity Weight of 8, meaning it significantly impacts your carrier's safety metrics and your own driving record.
Who gets cited most
Our inspection records over the last 180 days show 393.71 citations concentrated in three states:
- Texas: 3 citations, 1 placed out of service (33.3% OOS rate)
- Illinois: 2 citations, 2 placed out of service (100.0% OOS rate)
- North Carolina: 1 citation, 1 placed out of service (100.0% OOS rate)
Notably, Illinois and North Carolina showed a 100% OOS rate in our recent data, whereas Texas saw one-third OOS placement. This variation suggests either stricter inspection protocols in those states or varying defect severity—but all three states have flagged this violation.
Our data shows fleets such as M D Z TRUCKING LLC with 3 all-time citations for 393.71, the highest count in our database. Other carriers including LOVEY'S TOWING AND RECOVER LLC, WASTE MANAGEMENT OF OHIO INC, and others also appear, though with lower citation counts. No single carrier dominates, suggesting 393.71 is distributed across the industry rather than concentrated in one operation.
How severe is this compared to similar codes
Code 393.71 sits in the Vehicle Maintenance category alongside many other structural and mechanical violations. Let's compare:
- 393.9 (Inoperable required lamps): 660,737 all-time citations, 15.4% OOS rate. This is far more common but much less likely to result in OOS.
- 396.3(a)(1) (Inspection/repair/maintenance – general): 236,919 citations, 45.3% OOS rate. More frequent than 393.71, and a higher OOS rate, but still 24.6 percentage points below 393.71.
- 393.47E (Slack adjuster defective): 180,363 citations, 0.0% OOS rate. Another brake-related defect cited much more often, but almost never placed out of service in our records.
The sharp contrast underscores that 393.71's high OOS rate (69.9%) is unusual even within vehicle maintenance codes. Inspectors and enforcement agencies treat fifth wheel defects as immediate safety hazards warranting removal from service.
How to avoid it
Fifth wheel failures don't happen overnight. A systematic pre-trip inspection routine is your best defense:
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Walk the coupling point daily. Before departure, physically approach the fifth wheel from the side and rear. Look for visible cracks in the casting (the main body), rust that has eaten through metal, or debris lodged in the coupling. Press up and down on the trailer kingpin connection—there should be zero vertical play. If you can move it by hand, the locking mechanism is failing.
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Check all fasteners and locking pins. Visually confirm that the locking jaw pins (the two horizontal pins that secure the kingpin) are fully seated and their retaining clips are present and tight. Missing or loose pins are the most common reason for citations. Use a flashlight if needed; corrosion hides in shadows.
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Inspect for corrosion and pitting. Salt, road chemicals, and moisture accelerate rust on fifth wheels. If you see orange-brown discoloration, pitting, or surface deterioration, report it to your dispatcher or maintenance team immediately. Surface rust may be cosmetic; deep pitting that removes metal thickness is not.
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Monitor brake and coupling systems together. Our inspection records show that 393.47E (slack adjuster defect) and 393.48A (inoperative/defective brakes) commonly appear alongside 393.71 citations, suggesting that brake wear and fifth wheel wear can develop in parallel. If your brakes feel spongy or your trailer bounces excessively, have the fifth wheel inspected as well.
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Know your vehicle. Top vehicle makes cited for 393.71 include FRHT (9 citations), FORD (5 citations), and VOLV (5 citations). If you operate one of these models, be especially diligent. Fifth wheel designs vary; learn your tractor's coupling points and normal appearance so you can spot changes.
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Report maintenance needs immediately. Don't defer fifth wheel service. A loose pin or small crack will worsen with every mile and load cycle. Early reporting keeps you and other road users safe and prevents the roadside citation that could ground your truck for days.
If you've just been cited for 393.71, your vehicle is likely out of service until repairs are verified. Work with your carrier's maintenance team to document the repair (new fifth wheel assembly, re-welded mounting bracket, or full hardware replacement, depending on the defect), and request a follow-up inspection to clear the violation. Your safety record depends on it.