NHTSA Investigation PE13032

Trailer Structural Cracks

This investigation was open based on information ODI received through Early Warning Reporting.After gathering data, interviewing fleets and analyzing the available information ODI has not identified a safety defect trend.In response to an ODI request, Cornhusker reported 36 warranty claims related to the alleged defect.None of the claims resulted in a loss of vehicle control.In all cases the driver identified the component failure and placed the vehicle out of service without incident.ODI was concerned that a structural member failure would allow the trailer to separate or to drop down and contact the drive tires and increase the risk of a crash.However, no reports of these conditions were received. ODI also requested fleet contact information and spoke with five fleets.When asked if this condition created a safety risk, none answered affirmatively.All responding fleets were easily able to identify the failure and get it corrected without injury or property damage.Cornhusker provided a finite element analysis (FEA) of the failure area that showed how the structural members were failing and explained that the area in question was ahead of the kingpin and centered in the middle of the trailer.Cornhusker stated that even in cases of extreme neglect and failure, the pin plate bowed up slightly, but showed no signs of the trailer separating or falling down on the tractor driving wheels.In comparing the failure mode on the trailers subject of this investigation with trailers that have been recalled for similar failure modes, ODI found that in recall 06V-336 from Wilson Trailer Co. the area in question was behind the kingpin and to the side where the assembly attaches to the trailer bottom rail.When structure in this area fails, the trailer could fall down and contact the driving wheels on the tractor causing loss of vehicle control.ODI found that the average in-service time to failure was 34 months, with 93% of failures occurring prior to 4 years of service.At this time, the majority of trailers (77%) have already passed this milestone.Cornhusker has been requested to notify ODI of any additional failures which occur prior to March 31, 2015 at which point all of the subject trailers will have reached 4 years in service.ODI is not aware of any allegations of subject trailers becoming detached or contacting the drive wheels of the towing vehicle due to the alleged defect.There have been no reports of crash or loss of vehicle control related to the alleged defect.There have been no reports of property damage beyond the subject trailer and all affected trailers have been repaired and returned to service.There have been no reports of injury or death.A safety-related defect has not been identified at this time and further use of agency resources does not appear to be warranted.Accordingly, this investigation is closed.The closing of this investigation does not constitute a finding by NHTSA that a safety-related defect does not exist.The agency will take further action if warranted by the circumstances.

An investigation is a separate record from a recall and from a manufacturer communication. A manufacturer campaign to repair a safety defect or a failure to meet a federal safety standard.