393.47 Violation: What It Means and How to Fix It
Data through September 24, 2026 · Last updated October 28, 2026 · By Chad Griffith, founder
Quick Answer
393.47 (Brake actuators, slack adjusters, linings/pads and drums/rotors) was cited 48,739 times in roadside inspections of interstate for-hire carriers with 5 to 50 trucks from September 25, 2024 to September 24, 2026, and 8.8% of those citations put the driver or vehicle out of service. The most common version is 393.47E: Brake Out of Adjustment - Roto Clamp (Short & Long) DD-3 or Bolt.
48,739
Citations on carriers with 5 to 50 trucks
8.8%
Out of service
222,992
All carriers, same period
What the rule says
Brake actuators, slack adjusters, linings and drums must be in adjustment and within wear limits (49 CFR 393.47).
When it puts you out of service
One brake out of adjustment is not out of service (393.47E, 0.0%), but enough of them on one combination becomes brakes out of service under 396.3, the 20% rule.
The codes on the inspection report
| Code | What the officer wrote | Severity weight | Citations, 5 to 50 trucks | Out of service |
|---|---|---|---|---|
| 393.47E | “Brake Out of Adjustment - Roto Clamp (Short & Long) DD-3 or Bolt” | 4 | 36,451 | 0.0% |
| 393.47A-BCLMBD | “Drum Brake - Cracked/loose/missing lining/pad” | 4 | 1,780 | 3.6% |
| 393.47A-BCFSBD | “Drum Brake - Contaminated friction surface” | 4 | 1,753 | 6.1% |
| 393.47A | “Inadequate brakes for safe stopping - Brake Lining condition” | 4 | 1,515 | 32.0% |
| 393.47D2-BLTBD | “Drum Brake - Inadequate lining/pad thickness” | 4 | 1,468 | 8.1% |
| 393.47A-BCLMBD-SA | “Drum Brake - Cracked/loose/missing lining/pad on a steering axle” | 4 | 586 | 92.3% |
| 393.47A-BCFSBD-SA | “Drum Brake - Contaminated friction surface on a steering axle” | 4 | 563 | 97.9% |
| 393.47A-BCFSAD | “Air Disc Brake - Contaminated friction surface” | 4 | 424 | 8.0% |
| 393.47A-BRC | “Brake - Rotor (disc) with a crack in length of more than 75% of the friction surface or thru the rotor” | 4 | 410 | 99.3% |
| 393.47B | “Mis-matched brake chambers on same axle” | 4 | 377 | 91.5% |
| 393.47A-LJN | “Brakes - Loose/Missing Jam Nut” | 4 | 347 | 0.0% |
| 393.47B-BMBCBD-SA | “Drum Brake - Mismatched brake chamber sizes on a steering axle” | 4 | 344 | 100.0% |
How it scores (violation points)
How it scores: in FMCSA's Safety Measurement System each violation counts its severity weight, plus 2 if it put the driver or vehicle out of service, times 3 in its first 6 months, 2 from 6 to 12 months, and 1 from 12 to 24 months. FMCSA has approved a simpler scale that is not live yet.
How to fix it
- Find out why the brake went out of adjustment; an automatic slack adjuster that keeps needing manual adjustment is itself a defect (see 393.53).
- Repair the brake and record the pushrod stroke after the repair.
- Check stroke on every brake of that combination before it moves.
Stop it happening again
- Measure pushrod stroke at every preventive maintenance service and write the numbers down.
Challenging it in DataQs
Use DataQs (dataqs.fmcsa.dot.gov) only when the report is wrong: the wrong carrier or vehicle, a violation that did not happen, or a citation a court dismissed without a fine or found you not guilty of, which removes it from the Safety Measurement System; a conviction of a different charge lowers its weight to 1 (FMCSA adjudicated citations policy). Fixing the defect afterward is not a reason to remove it; keep the repair record instead.
FileFlo reads your public FMCSA record, lists every violation with the rule behind it, and keeps the driver and vehicle records that stop repeats.
Run it yourself: the Audit-Ready Setup, $499 through December 31, 2026, then $199 a month for up to 15 trucks. Or FileFlo runs it: $1,500 a month for up to 15 trucks, Setup included, and your first month back if you are not happy.
About these numbers
Counts are violations cited in roadside inspections used in FMCSA's Safety Measurement System from September 25, 2024 to September 24, 2026 (dataset 8mt8-2mdr on data.transportation.gov, October 2026 run). Carriers with 5 to 50 trucks means 66,936 active interstate for-hire carriers with 5 to 50 power units and more trucks than buses, based in the 50 states or DC, from FMCSA's census file. This is FileFlo's reading of public FMCSA data, not an FMCSA rating. Severity weights are the current SMS weights.