Abstract: On the basis of assumed constant failure rate and determined repair time at upper α% point for each unit within complex repairable systems such as ground vehicles and automobiles, a mathematical approach to dependability modeling regardless of the probability density of maintenance time, has been developed by means of description of multiple critical failures to occur or having occurred in the operation of the complex repairable system, and the procedure of estimating mission maintainability with statistical inference is presented in the paper. Finally, the effect of the time allowable for maintenance, malfunction number and repair time at upper α% point for each unit upon system dependability is explored through the example of a four unit repairable series system, and we quantificationally analyze in sufficient detail the relationship of dependability between reliability, maintainability and supportability, which could be used to the system configuration optimum and recovery from malfunction. The approach proposed in the paper would give a new basis for dependability modeling.

Key words: dependability, m ission maintainability, repairable series system, mult ip le crit ical failures