SCENARIO: Two trainees were assisting two qualified maintenance engineers during a quiet period of the shift. They were carrying out an in-house routine maintenance activity on an electrically-powered conveyer that was usually in 24-hour operation. The conveyor had been electrically isolated using a Lock Out, Tag Out system, and allowed to cool for almost 2 hours. Barriers were erected around the machinery, as well as signage to warn of the maintenance activity. One of the maintenance engineers asked the two trainees to remove the conveyer motor for cleaning. The trainees proceeded to do this, while the maintenance engineers were called away on another job. Once the electric motor was removed, the trainees decided that it needed replacing due it its condition and age. The correct model was collected from the spares storage room (no permit-to-work (PTW) system or equivalent safe system of work (SSoW) was in place to authorise this). Neither of the trainees had done this type of work unsupervised before. However, using the equipment manufacturers manual as a guide, they felt confident enough to carry out the task safely. The conveyer was required to be back in service as quickly as possible, so they had to rush to get the job done. Some of the guards around the machinerys gears and chains were removed to provide better access. When the job was completed, neither of the trainees had noticed that they had failed to reinstate the machinery guards. Locks, tags, and signage were removed, and the power switched back on. The next day a bakery workers clothing was caught in the conveyor belt motor mechanism. The worker reacted quickly, pressing the emergency stop button, but it did not stop the conveyer. The worker was seriously injured as a result. A subsequent investigation identified that the guarding was missing. It also identified some electrical faults. These faults resulted in a further shutdown of the conveyor to effect repairs.

Task: Maintenance:

3 (a) Based on the scenario only, what went well with the recent routine maintenance activity on the electrically-powered conveyor? (8)

3 (b) Based on the scenario only, what did not go well with the recent routine maintenance activity on the electrically-powered conveyor? (10)

3 (c) Comment on what should have been considered when deciding on the frequency of a maintenance programme at the bakery. (15)