In the maintenance procedure, basically, how you will do the maintenance, where to register, your failure maintenance intervention method, your periodic maintenance types, your predictive maintenance types, and their frequencies should be explained. It is also good to mention your analysis method and actions to be taken for frequent maintenance failures.
It may also be necessary to mention how and where to store spare parts and their minimum & criticality levels. Maintenance instructions should be written separately for the equipment. It would be good to have information such as how often equipment will be maintained, where to check, and how often to change.