Investigations
Failing 5th wheel attachment bolts
NHTSA Preliminary Evaluation PE10042 — closed, opened 2010-11-04 and involving the MACK CXU612.
NHTSA investigation PE10042 is a Preliminary Evaluation opened on 2010-11-04 and currently closed. The subject of record is MACK CXU612, which places this file inside the Office of Defects Investigation queue for MACK. Latest activity on this investigation was logged on 2011-04-27 — NHTSA updates that field whenever an Information Request goes out, a supplement is filed, or a status change is recorded in the public docket.
A Preliminary Evaluation like PE10042 is the entry point of the federal defect-investigation process. NHTSA engineers scan complaint databases, field reports, and manufacturer data to decide whether an Engineering Analysis is warranted, whether a voluntary recall is already sufficient, or whether the pattern does not rise to a defect finding.
Investigators summarized the matter as follows: "On October 3rd 2010 the Office of Defects Investigation (ODI) received two complaints on 2009 - 2010 Mack CXU612 and CXU trucks for failing bolts that clamp the 5th wheel to the frame of the truck. On January 19, 2011 OD..." Investigations are the early-warning layer of the federal auto-safety system, sitting upstream of formal recalls and defect orders. Whether this one closes without action or escalates into an Engineering Analysis, the full history stays in the ODI archive so researchers, litigators, and buyers can pull the paper trail at any time. Related MACK files, listed below, give context on whether this is an isolated concern or part of a broader pattern across the brand.
Investigation Summary
On October 3rd 2010 the Office of Defects Investigation (ODI) received two complaints on 2009 - 2010 Mack CXU612 and CXU trucks for failing bolts that clamp the 5th wheel to the frame of the truck. On January 19, 2011 ODI opened this Preliminary Evaluation. During the course of the investigation ODI took possession of fasteners from the field. These fasteners, taken off subject complaint vehicles, exhibited 'hourglass like stretching' indicating plastic deformation. This same source supplied ODI with new fasteners (for the subject vehicle) that were recently purchased and never used. The bolts supplied by the manufacturer are M16 x 2 Class 10.9 bolts. Per SAE J1199, these bolts should have a proof load 130 kN (~29,000 lbf) and tensile strength of 163 kN (~36,600 lbf). These bolts are not designed to be torque to yield. ODI took possession of these field samples and sent them to (VRTC) Vehicle Research and Testing Center for testing. Some of the new and used fasteners from the field were tested to the SAE J1199 standard and all passed. Other tests at VRTC indicated that the stretched bolts were likely the result of over torque during installation or maintenance. VRTC tested other methods to pre-tension the bolts and found that load indicating washers and turn-of-the-nut method both gave better clamping load control than a torque wrench. In February 2011 Mack started to perform field inspections associated with this investigation in an attempt to understand the cause of the bolt failures. During these inspections, Mack discovered that there was an interference with the bolts used to secure the fifth wheel to the frame. This interference can prevent the bolts from being torqued to specification. If this occurs, the bolt(s) may fail and in extreme cases may result in the fifth wheel coming loose causing the trainer to separate from the tractor. Mack has issued a voluntary Safety Recall 11V-209 for (failure of fifth wheel mounting bolts). However, claims in the field sug
About This Investigation Type
A Preliminary Evaluation (PE) is the first phase of NHTSA's investigation process. It is opened when the agency identifies a potential safety defect pattern, usually triggered by consumer complaints, manufacturer reports, or field monitoring. During a PE, NHTSA gathers information to determine whether a formal engineering analysis is warranted.
Other MACK Investigations
mDrive Transmission Failure to Disengage
Vehicle Roll Away
AIR COMPRESSOR DISCHARGE LINE
INTEGRAL HUB AND BEARING ASSEMBLY
Data from NHTSA Office of Defects Investigation. Cross-references: NHTSA recall campaign API and NHTSA FARS where fatality records overlap. PlainCars does not rate or recommend vehicles. Learn more.
Read our methodology — how this data is sourced, computed, and verified.