Coal Inspectorate | Alert | No.390 V 1 | 18 May 2021

Dragline hoist drum uncontrolled movement

What happened?

A dragline hoist drum was to be rotated to enable rotation of a hoist motor. This was to allow conditioning work to be done on the hoist motor commutator. The rotational energy would come from the release of the bucket and hoist rope movement. No other controls were in place. One hoist brake was released at a time until hoist drum rotation commenced. Seven out of eight hoist brakes were released until this movement was achieved. The bucket started accelerating into the pit from boom point until it reached maximum velocity. With no controls to stop this movement, the hoist ropes (127mm) continued to unwind off the drum until the end of the rope was reached and the 16 hoist rope clamps were ejected from the drum, becoming projectiles in the machinery house area. During this time, hoist brakes were trying to be set manually and as they were applied large quantities of brake pad dust was released into the machinery house area. No one was injured during this event. The incident is still under investigation.

How did it happen?

The uncontrolled release of hoist brakes and bucket from a significant height, combined with no controls contributed significantly to this event. The hazards posed by the uncontrolled release of the hoist brakes and dragline bucket were not identified by the personnel in any formal process.

Key issues

There was no formal instruction or procedure for the rotation of the hoist drum in this manner. This was also a contributing factor.

Recommendations

1. SSEs should ensure the Safety and Health Management System provides for a way of conducting this task so as to achieve an acceptable level of risk.
2. When job tasks change from original plans or when previously unidentified hazards become apparent, all personnel should stop and reassess before proceeding with the task.
3. Consideration should be given to consulting relevant work instructions when formulating JSAs.
4. All personnel need to be aware of the content of instructions and procedures associated with tasks in hand.
5. Location of personnel and proximity to hazards need to be identified when conducting tasks.
6. All potential energy sources (potential or kinetic) should be recognised so that risks and hazards can be managed.
7. Current site procedures must continue to maintain an acceptable level of risk.
8. SSEs review site procedures for conducting "live" work. Alternatives to conducting "live" work should be considered. Where "live" work must be undertaken ensure the controls are appropriate.