The major issue in reliability analysis of a system is the difficulty inprocurement of data or the missingness in the available data of a system and its components. The data could be either failure time data, repair or replacement timeor the information related to the availability of the components or the system. The missingness in data could seriously affects the outcome in reliability analysis.In this work, we deal with the problem of missingness in the failure time data, also known as incomplete or partial failure data (Time Between Failures) of repairable components of a system in reliability analysiswith the aid of “Missingness Graphs” or m-graphs technique. This m-graphs represents the causal mechanism responsible for missingness and the dependencies between causal mechanism and variables being measured.After m-graph construction, we check whether the graph is satisfying the conditions which are needed to ensure the recoverability of the missing data. The term “recoverability” implies checking whether there exist a consistent estimate for any given relation. To illustrate the applicability of the proposed approach, a case study of rolling mill gear box has been presented to check the recoverability of the Time Between Failure data of components in it.