Description of the accident

The injured (driller assistant) and a colleague were in the process of loosening the quillrod in order to pull it out of the chuck.

They engaged their spanners on either side of the rod as shown in the photograph below. Just as the injured man was about to loosen the drill rod the chuck and therefore the drill rod rotated unexpectedly pulling the drill rig assistant towards the drill rig, jamming his right hand between the spanner and the substructure of the drill rig. This resulted in the traumatic amputation of his right middle finger.

Apparent causes

1. Lack of communication between the Driller and the drill rig assistants.

2. The Driller was in a hurry to complete the task.

3. The Driller did not adhere to the procedure that states clearly that he must ensure that the drill rig assistants are 2 metres away from the rig when the drill rig is in rotation mode.

Additional factors

Judging by the condition of the larger diameter tube it is suspected that it is a corebarrel and the crew were attempting to break the joint between the quillrod and the corebarrel. It appears also that the crew wanted to butt the spanner held by the injured man against the frame of the drill rig so that torque could be applied to the other spanner. This is not an uncommon practice in the industry.

The accident report states that the chuck and therefore the quillshaft and quillrod rotated uncontrollably while the drill rig assistant was still holding the spanner. This could only have happened if the Driller had the drill rig engaged in rotation mode. It is unclear how the drill rig came to be engaged in rotation mode – based on the assumed sequence of events the Driller would have hoisted the quillrod to the point that it is shown in the photographs in which case the drill would have been in hoist mode. The Driller may have then placed the drill in rotation mode in error.

Alternatively, it is possible that the Driller pulled the quillrod to the position shown by using the hydraulics of the drill – if this were the case then the drill could still have been in rotation mode.

Whatever the case there should have been a very well defined and well enforced Standard Operating Procedure which eliminated the risk of the chuck rotating while men were working on the drillstring. This can be achieved by placing the drill in neutral or by switching the drill off. In either case the Driller must remove himself from the area around the controls to eliminate the possibility of him accidentally engaging the drill.

It is clear that this was not done and the Driller either accidently or with intent engaged rotation of the drill. This indicates a very poor attitude to safety and ignorance of the hazards and the risks associated with an operational drill rig on the part of the Driller. More importantly, this indicates a lack of close supervision of the drill crew.

Recommendations

Drilling is an occupation which requires the Driller and drill rig crew to carry out many repetitive actions in the course of a day. Sound safety management systems will include operating procedures that ensure that all hazards are identified and the associated risks eliminated or reduced to an acceptable level. A sound safety management system will include a series of SOP’s to cover all hazardous tasks but often these procedures are bypassed because the Driller finds them onerous or because they take too long - the “revised” procedure then becomes the norm. Proper supervision should identify these “short cuts” but very often this does not happen either because the level of supervision is inadequate or because the Supervisor does not know any better.

1. It is essential that all operational staff; drillers, drill rig assistants, Supervisors and Contract Managers are fully trained in all aspects of the drilling operation and that they are properly assessed and before being allowed to work on a drill site.

2. It is essential that all operational staff; drillers, drill rig assistants, Supervisors and Contract Managers are fully trained in the identification of the hazards associated with an operational drill site before being allowed to work on a drill site.

3. All operating procedures must be interrogated to ensure that all identified hazards have been adequately mitigated.