Failure of a fairground ride

Abstract

On 22 February 1997, one of the arms of an “Octopus” amusement ride, operating at the Rylestone Show in New South Wales (NSW), Australia, became detached from the central pylon, allowing the passenger carriage at the end of the arm to fall to the ground. This accident resulted in the death of one of the three young occupants. The Octopus ride is shown after the accident in Fig. 1. The ride had eight arms that rotated along with the central pylon while also moving up and down by pivoting through an axle attached to the central pylon. The axle pivoted in two bearings (one at each end of the axle) fitted to housings attached to the central pylon. To allow disassembly of the arms when the ride was transported from town to town, a cast steel bearing cap was fitted to the top of each housing. The cap was hinged to the housing at the inboard end and bolted to the housing by a retaining bolt at the outboard end.

Detachment of the arm was found to have occurred as a result of fracture of the bearing cap and the retaining bolt, which then allowed the axle to move out of its housing. The ride was first registered in 1956 (the year that registration became compulsory in NSW) but had been in service for some time prior to that and may have been built as early as 1939.^[1] This paper presents the findings of a metallurgical analysis of the failure.