Forensic Engineering Analysis of a Fatal Trailer Wheel-Separation Failure

Abstract

A forensic analysis of a fatal trailer wheel-separation failure is presented in this paper. An older three-axle trailer carrying snowmobiles was being driven at highway speed during winter time in Michigan. The left front wheel detached due to the catastrophic failure of all six lug studs. The wheel traveled into the on-coming traffic lane and struck the roof of a sedan driven by a local student. The driver of this vehicle was killed instantly due to passenger compartment intrusion. One possibility was that the lug nuts were improp-erly tightened during a recently performed service — and that this looseness diminished clamping forces and led to cantilever bending of the studs and fatigue fracture. An analysis of the defendant’s narrative and of the failure were performed.