What 393.71(g) means in plain language
When an inspector cites you for 393.71(g), they're saying your fifth wheel assembly doesn't meet safety standards. The regulation covers three scenarios: the fifth wheel is structurally defective, it shows excessive wear that compromises function, or it isn't properly secured to the vehicle frame.
The fifth wheel is the kingpin coupling mechanism that connects your tractor to a semi-trailer. If it's loose, cracked, missing fasteners, or worn beyond safe limits, an inspector will flag it. This is a direct safety issue—a failed fifth wheel can cause trailer separation during transit, a catastrophic event.
Being cited for 393.71(g) doesn't automatically mean you're out of service at the roadside. But it does create a documented maintenance record that will appear on your CSA profile and your carrier's inspection history. The citation carries a CSA severity weight of 8, which is moderate in the vehicle maintenance category.
What our enforcement data actually shows
Across our 13 million+ inspection records, 393.71(g) has been cited only 16 times all-time. In the last 12 months, we've recorded zero citations, and zero in the last 90 days. This makes 393.71(g) one of the least-cited codes in the FMCSR database—it ranks #2026 out of 3,036 codes by citation volume.
When 393.71(g) violations do occur, 12.5% result in out-of-service placement. That's significantly lower than the all-FMCSR average OOS rate of 31.4%, meaning inspectors typically issue it as a warning citation rather than an immediate shutdown. Of the 16 all-time citations, 14 were not placed out of service and 2 were.
The rarity of this citation suggests that most drivers and fleets are maintaining fifth wheels within acceptable limits, or that inspectors reserve this code for cases where wear is present but structural failure hasn't yet occurred.
Who gets cited most
Because the total citation count is only 16 across the entire TruckCodex database, no single state or carrier shows a dominant pattern. Our data shows individual citations distributed across multiple carriers, each with one or two instances. Among vehicle makes, Volvo appears in 3 of the 16 citations, followed by Chevrolet and Ford with 2 citations each. The remaining citations are spread across International, Big Tex, and various other manufacturers.
This distribution doesn't point to a systematic problem with any particular brand or fleet size. Rather, it reflects that fifth wheel defects are episodic—they occur when a specific unit has been neglected or when wear accumulates faster than expected due to heavy use or poor maintenance scheduling.
How severe is this compared to similar codes
In the vehicle maintenance category, 393.71(g) sits at the low end of enforcement frequency. For comparison:
- 393.9(a) — Inoperable required lamps has been cited 660,737 times with a 15.4% OOS rate. Lamp defects are far more common but trigger out-of-service placement less often than the all-FMCSR average.
- 396.3(a)(1) — Inspection/repair/maintenance - general has 236,919 citations and a 45.3% OOS rate, making it both more frequent and more likely to result in roadside shutdown.
- 393.47E — Slack adjuster defective has 180,363 citations but only a 0.0% OOS rate, indicating inspectors rarely ground trucks for brake slack adjuster issues, even though they cite them regularly.
By these comparisons, 393.71(g) is rarer than all major peer codes, with an OOS rate that sits between the lamp category and the general maintenance category.
How to avoid it
Fifth wheel maintenance is straightforward and best handled during your regular pre-trip inspection:
- Visually inspect the fifth wheel before every trip. Look for cracks in the casting, missing or bent fasteners, rust that has eaten through metal, and any visible gap between the fifth wheel and frame. If you see daylight where metal should be, report it.
- Check kingpin wear. The kingpin (the vertical pin on the trailer that locks into your fifth wheel) should not be loose or visibly corroded. A worn kingpin and a worn fifth wheel can amplify each other's problems; if one needs replacement, both may need inspection.
- Verify fastener tightness. Fifth wheels are bolted to the frame. If bolts are loose, the entire assembly can shift under load. Use a wrench to confirm fasteners are snug during your walk-around, or report any that move.
- Report wear to your fleet immediately. Fifth wheels don't fail suddenly in most cases—they degrade over miles. If you notice the coupling feels looser than it used to, or you hear creaking when coupling/uncoupling, flag it for service instead of waiting for an inspection.
- Know your vehicle's age and usage. Older trucks and high-mileage tractors accumulate wear faster. If your fifth wheel is original to the tractor and the truck has six or more years of service, proactive replacement or re-certification during your next scheduled maintenance can prevent a citation.
Fifth wheel defects are cited rarely, but they're also easy to prevent with basic attention during pre-trip inspections. The low citation rate suggests that drivers who do a thorough walk-around catch these issues before an inspector does.