Prevention FAQ — FMCSR 393.201E: Frame Rail Flange Holes

Inspectors examine the frame rail flange—the vertical lip that runs along the outer edge of the main frame rails—for any holes that have been drilled without authorization. These holes weaken the frame structurally and are prohibited by federal regulation. Across our 13 million inspection records, we see only 2 all-time citations for this code, placing it at rank #2651 of 3,036 FMCSR codes. This low citation volume suggests that either fabrication and assembly are tightly controlled by OEM, or inspectors rarely encounter it. Inspectors will use a visual walkround and may use a flashlight to peer into the area where the flange meets the frame web. They look for drill marks, rivets or fasteners that don't belong, or visible penetrations. If found, the violation is straightforward: the hole exists and should not.

Add a dedicated frame rail flange inspection step to your standard pre-trip walk-around. The driver should visually scan the full length of both sides of the frame (driver and passenger), paying special attention to the flanged edge where it's most visible. Use good lighting and inspect for: (1) any new holes, cracks, or rust-through in the flange; (2) loose rivets, fasteners, or evidence of unauthorized attachment points; (3) welding slag or burn marks suggesting field repair work. Document the date and driver signature on a checklist or mobile app. If the vehicle has recently been in a collision, body shop, or undercarriage wash, prioritize this inspection. Make it part of your driver safety briefing that unauthorized frame modifications—even if done to add accessories—are a federal violation and grounds for OOS status at certain scales.

Drivers should carry the vehicle's original OEM specification sheet or frame diagram, if available, showing where drilling or fastening is and is not permitted. The carrier should retain: (1) the original manufacturer's frame assembly documentation for each vehicle model; (2) photographs of the frame rail flanges taken during initial intake or after any body shop, collision repair, or modification; (3) a work order or authorization log for any aftermarket equipment installation, with dates, what was installed, and how it was fastened (welding, bolting to pre-drilled points, etc.). If a driver reports concern about holes or cracks, document that report, the inspection date, and any corrective action taken. This paper trail protects you in a DataQs challenge and proves due diligence.

Our inspection data does not provide co-occurring violation codes paired with 393.201E, so we cannot identify statistically linked systemic issues from this dataset. However, structurally, frame rail holes typically arise from: (1) unauthorized aftermarket equipment installation (mud flaps, step boards, light bars, mud guards) where technicians drill into the flange instead of using existing fastener points; (2) collision repair shops drilling new mounting points rather than replacing damaged flanges; (3) field repairs where a technician reinforces or patches the frame incorrectly. To prevent this, establish a vendor qualification process: require all body shops and fabricators to confirm they will use OEM-approved fastening methods only, and conduct a pre-work inspection before releasing any vehicle for non-routine work. Train your maintenance staff to refuse unauthorized drilling.

If a frame rail flange hole is discovered, the repair must restore structural integrity. Approved approaches include: (1) welding a reinforcing plate over the hole (if small and not in a high-stress zone) and grinding smooth; (2) removing and replacing the damaged flange section (preferred for larger damage); (3) frame straightening or replacement if the flange is bent or cracked. After repair, require a licensed frame shop to sign off with a work order stating the method used and confirming the repair meets OEM standards. Take photographs before, during, and after repair. Do not permit a temporary patch or sealant as a fix. Before the vehicle re-enters service, a supervisor or safety manager must visually inspect the repair site in daylight and sign the repair authorization. Document the date and person responsible for verification.

Immediately after a citation, conduct a root-cause investigation: (1) interview the driver and the mechanic who last worked on the vehicle; (2) determine when the hole was drilled (during initial assembly, a prior repair, or recent maintenance); (3) identify who performed the work and whether they had authorization; (4) check if this vehicle had recent body work, accessory installation, or downtime; (5) inspect the entire fleet for similar holes on the same make/model. Our data shows 2 all-time citations split between Freightliner (FRHT) and Kenworth (KW), so flagging same-make vehicles is prudent. Review the work orders for all maintenance and modifications performed on the cited vehicle for the past 12–24 months. Determine if your vendors or in-house technicians understand OEM fastening requirements. Issue a fleet-wide memo to mechanics explaining that frame rail drilling is prohibited, and direct them to contact the shop supervisor before any non-standard fastening work.

A 393.201E citation counts toward your Vehicle Maintenance BASIC score under the CSA Safety Management System. However, our data shows this code has a 0.0% out-of-service rate—none of the 2 all-time citations resulted in OOS placement—compared to the all-FMCSR average of 31.4%. This suggests the violation is treated as a defect-level finding rather than a safety-critical condition. Nonetheless, the citation still weights against your maintenance BASIC percentile. To minimize impact: (1) ensure all future inspections find no similar issues (demonstrate remediation); (2) if you believe the citation was issued in error, file a DataQs challenge within 90 days with supporting documentation (OEM fastening records, photographs showing no holes exist, or corrective action evidence); (3) document your preventive inspection and training program to show the issue was isolated and addressed.

Design a two-tier training program. For drivers: (1) frame integrity basics—why drilling the frame rail is prohibited, the structural consequences, and their role in spotting unauthorized damage; (2) what to report during pre-trip inspection (cracks, holes, loose fasteners on the flange); (3) when to reject a vehicle assignment if frame damage is suspected. For mechanics and shop staff: (1) OEM frame assembly standards—where fastening points are located and why drilling outside those points is forbidden; (2) approved fastening methods for common accessories (mud flaps, steps, lights); (3) how to handle retrofit requests (consult OEM drawings, use existing holes, or refer to engineering before drilling); (4) welding and structural repair qualifications required for frame work. Tailor training to the most common vehicle makes in your fleet. Our data shows citations on Freightliner and Kenworth units, so use those OEM service bulletins as case studies.

File a DataQs challenge if: (1) you have evidence the hole was present before the driver took possession (pre-existing defect from the dealership or previous fleet); (2) the citation vehicle has not been in your fleet during the period the hole was drilled; (3) the hole exists in a location or shape inconsistent with the vehicle's actual frame design (suggesting a measurement or documentation error); (4) you have OEM certification or a frame shop report showing the flange is unbroken and sound. Submit documentation within 90 days of the citation: photographs with date stamps, OEM frame diagrams, work orders proving no drilling was authorized, and a signed statement from your maintenance manager. Given the extremely low citation volume (2 all-time), a DataQs challenge has a reasonable chance if your evidence is solid. Contact FMCSA's DataQs portal and reference your USDOT number, the inspection date, and the specific evidence.

Our inspection data shows 1 citation in the last 90 days and 2 total in the last 12 months, indicating this violation is extremely rare in the field. However, rarity does not equal zero risk. Implement a quarterly self-audit cycle: (1) every 90 days, inspect a random sample of 10% of your fleet or all vehicles assigned to drivers with high citation histories; (2) use a standardized form with the frame rail flange checklist; (3) document findings and corrective actions. Additionally, conduct a full fleet walk-through immediately after any body shop work, collision repair, or major maintenance. If any unauthorized drilling is suspected, pull the vehicle off the road, inspect thoroughly, and consult the frame OEM or a certified frame shop before returning to service. Because the all-time citation count is only 2, focus your audit resources on preventing the conditions that lead to drilling—unauthorized modification work—rather than assuming the violation is imminent.