For information purposes only. Managers & Supervisors should evaluate this information to determine if it can be applied to their own situations and practices.

Feed Cylinder
Drill string down
Hydraulic hose fitting
Steel wire rope
Sheave wheel

 Time: Between 11h04 -11h17
Fitter had completed daily checks on Drill and was undertaking the repair to an oil leak on the left side feed cylinder of the drill. Mechanic was observing Fitter as, Mechanic, was being coached on the workings & maintenance aspects of the drill. Fitter had requested the drill operator to raise the drill string [for] better access the leaking hose fitting to work on. Fitter took up a kneeling position with their right leg over the drill platform hole through which the drill string passes during drilling operations.
Fitter loosened the hydraulic hose fitting which connected to the feed cylinder. This resulted in the loss of hydraulic stored energy within the cylinder, resulting in the release of the drill string which plunged down and as it passed through the platform drill hole it resulted in the amputation of the right leg below the knee.
Mechanic had taken up a position on the right side of Fitter with back to the [drill] operators cabin. Mechanic was probably holding on to the steel rope, which passes under a sheave wheel for the control of the up & down movement of the drill string, with their right hand. When the pressure was released from the feed cylinder the power head ...[the] drill string moved downwards as did the steel rope [and the] Mechanics right hand was pulled through the sheave wheel resulting in the amputation of four fingers & thumb.
Slide 3

Drill string in a raised position (drill bit seen here)
Simulated position of the Fitter with his right leg over the drill hole

Hydraulic hose fitting that was loosened resulting in the release of stored energy

Root causes
•Loosening the hydraulic hose fitting connecting the hose to a hydraulic feed cylinder, and in doing so there was an uncontrolled release of oil pressure from the cylinder causing the drill string to fall.
•Stored energy not released prior to commencing activities.
Key contributing factors
• Did not take the time to plan and reflect on the risks of the task at hand.
• No formal risk assessment performed prior to the task.
• Insufficient understanding of the hydraulic system on the drill.
• Insufficient knowledge on the concept of stored energy.
• No guarding in place covering the moving sheave wheel.
Key learning's
• Awareness campaigns not enough to embed understanding of sources and consequences of stored energy.
• There is no substitute for taking time out to perform proper planning and understanding the risks involved prior to commencing any task.

• Launch a communication campaign in regard to stored energy in simple and clear terms
• Review, Verify, Sign off Risk Assessments that all stored energy risks are captured and high risk areas are covered by training interventions
• Guards to be fitted on all bottoms of sheave wheels on drills.
• Formally review guarding to ensure all moving parts are guarded
• Supervision verification through quality PTO’s and CTO’s. The one up line manager must verify the quality of a sample of PTO’s and CTO’s.
• Assess the capability of Supervisors in key critical areas to ensure they are competent to execute their responsibilities safely.
• Include stored energy in the COP for isolation, lock, test and tag.
• Update procedures to ensure that unplanned work (subsequent work) is properly planned and executed.
• Supervisors are notified of, pre-approve, and adequately mitigate risk in Remote work.