A longwall crew was replacing a broken drive shaft on the ranging arm of a longwall shearer. The drive shaft had a spline on each end and required alignment of the splines to be completely installed.
It appears that the drive motor rotated under power, catching and forcibly ejecting the shaft. A coupling housing was flung from the end of the rotating shaft, striking the victim.
Recommendations
Recognise that there are human factors involved in all aspects of maintenance.
Ensure actions and decisions of maintenance personnel do not leave plant in an unsafe condition.
Use safe work procedure, regardless of low risk or repetitive maintenance, when working on large energy plant.
Incorporate adequate independent inspections at key points of the maintenance activity in the safe work procedure.