This paper describes the integration of a sensor data stream monitoring system into a proposed functional product model capable of predicting functional availability. Such monitoring systems enable predictive maintenance to be carried out – pre-emptive maintenance that is scheduled in response to imminent hardware failure – and are in widespread use in industry. The industrial motivation for this research is that agreed upon system availability is a critical element of any business-to-business agreement regarding functional sales. Such a model is important when making strategic choices regarding FPs and can be used to develop a high availability product design through simulation-driven development, as well as to provide operational decision support that reflects the current reality to enable optimal availability to be achieved in practice. The proposed model integrates hardware, support system and monitoring system models, and is able to incorporate actual operational data. It has been partly verified based on previous research.