Alert 14 – 19 Dropped Object Results in Near Miss
During tripping and laying down of the cementing pipe string, the drilling crew discovered a 25.4 cm (10 inch) diameter, 0.68 Kg (1.5 lbs) brass thrust washer lying on the rear of the drill floor. The washer had fallen from the inside of the top sheave in the crown assembly of the derrick, missing the nearest worker by 2 meters (6.5 feet). A visual inspection, performed by the crew from the ground using a camera with a telephoto lens, identified that the sheave pin (which forms the axle for the sheave) had moved laterally and the sheave was noticeably leaning from its normal, vertical position. A crane equipped with a man basket was mobilized so that personnel could access the crown to inspect, render safe, and repair the damage. At this time it was observed that the outer sheave locking plate bolts had sheared and the plate itself was seen resting on the edge of the crown assembly. These conditions created the potential for a more serious incident, necessitating a suspension of rig operations.