An automobile was taken to a garage for a brake pad change. When the rear wheel was replaced, the lug nuts which held the wheel in place were improperly tightened. After one month of driving, the wheel came loose from the automobile and a one vehicle accident and personal injury resulted.
Photograph A Wheel which separated from the axle in the one vehicle accident.
Metallurgical failure analysis revealed that two of the five wheel lugs failed by metal fatigue. The lug nuts from the three remaining wheel lugs totally backed off allowing separation of the wheel from the automobile.
Photograph B View of axle plate and wheel studs.
The automobile wheel rim lug holes were completely wallowed out from their round shape during the one month driving time.
Photograph C Close-up view of wallowed out wheel stud hole in wheel rim.
The automobile accident occurred as a result of the rear wheel lug nuts being improperly tightened, allowing the rear wheel and tire to come loose and separate from the subject automobile.