reliability indicators (such as failure rate, outage time etc) and the approach adopted is still heuristic. The application is still based on experience and judgement at every turn. It takes a long time before enough data are collected for making such judgements [17]. To solve the identified problems above, a probabilistic representation of deterioration process is modeled. A mathematical formulation of the expected transition time from any deterioration state to the failure state (expected remaining life) has been proposed.