Interactions between maintenance and production and safety. Bibliographical study 1. Maintenance tasks: definitions and characteristics contributing to their criticality

For a long time, maintenance operations have been identified as "critical" situations where safety is concerned. This critical aspect results not only from the nature of these activities but also from their organizational context and from interactions between maintenance and production operators. Consequently, and given that few studies have been devoted to maintenance, we have conducted some research into the interactions between maintenance and production and their consequences for reliability and safety.
Within this framework, a bibliographical analysis was made. It was aimed primarily at acquiring knowledge about maintenance activities and identifying, on this basis, some characteristics of these activities contributing to their criticality. Secondly, we considered functional and organizational relationships of maintenance and production and their effects on the safety of maintenance activities. Finally, we investigated the interactions between the operators concerned and their potential consequences.
This paper, concerning the first of these objectives, is dedicated to maintenance activities. Firstly, "maintenance" is defined. Then, its object (equipment), its missions (the different types of maintenance) and its means (the different operations and activities of maintenance) are specified. Lastly, from these elements, some characteristics of maintenance activities, which may contribute to their criticality in terms of safety, are discussed.