Maintainability Assessment of a Complex System Based on Field Data

Maintainability assessments which are independent of the system developers can provide an impartial evaluation of a system's maintainability performance. This paper outlined one kind evaluation method to assess maintainability of a certain complex system based on field data. The field data of repair time of the system were collected, then the repair-time distribution of the system was identified by graphic estimation method, and the mean time to repair (MTTR) and the maximum repair time t(0.90) were assessed as well, and finally the results were compared with the system's specification. It is found that apart from some inaccurate data, the repair time of this complex system follows the lognormal probability distribution. A MTTR of 1.45 h and a maximum repair time of 3.44 h were observed. The maintainability requirement of the system is not being satisfactorily met.