The goal of this group is to come up with all the different ways in which each hour of unexpected downtime is negatively impacting your company. Here is a brief list to help you get started:
Loss in staff productivity
Loss in actual production of goods
The number of man hours devoted to re-scheduling both the maintenance plan and the production plan
Reputational and financial consequences of increased delivery time
Express orders of missing spare parts
Once you have this list, try to put a monetary value to each consequence to find out which effects cause the most damage and to what amount all these different costs add up. This is the hardest part and there’s no exact science as to how to do this, but even a rough estimate will already help you a lot.