The main aim of this study is to identify the most critical subsystem of the production plant by using failure and repair data. Time-between-failure (TBF) and time-to-repair (TTR) data are collected to estimate reliability, availability, maintainability, dependability, and mean-time between hazardous failures (MTBH). The dependability parameters are solely applied to those subsystems that have both constant failure rate and repair rate. Various measures of plant performance such as MTTR and MTBF are as well presented. Performance modeling of the system is carried out based on the assumption that both repair and failure data are statistically independent. To show the application of the proposed method, the NPK fertilizer production line as a repairable production system has been provided for performance evaluation. The records of failure and repair data can be a useful database for the management of NPK fertilizer production line to improve system reliability.