Case Study: Chair Injury

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A woman had been injured when a swivel-style patio chair failed causing her to fall backwards. The purpose of the investigation would be to determine if there was any information or evidence which would indicate the cause of the chair failure.

Based on background information, research, examination, and analysis conducted during the investigation, Omnitek Engineering, Inc. concluded the failure of the subject chair was a result of the chair having been defective in design and unreasonably dangerous. 

Supporting evidence for this conclusion included: 

The description of the incident and the failure location indicated by the injured woman was consistent with the chair failing through a leg section(s) near the weld(s) used to secure the leg section(s) to the chair’s center hub. 

A metallurgical examination of two additional chairs which had been in the same use at the same location as the subject chair and purchased at the same time as the subject chair, revealed their legs had cracks indicating failure of the legs was occurring. 

An analysis of the failure location of the chair leg determined the leg design was inadequate for the intended use of the chair. The stress at a curved leg member at the point of failure exceeded the permissible stress for an aluminum fillet weld leg design.