Flooding and broadcasting are basic and fundamental operations in Wireless Sensor Networks (WSNs). In fact, they are used for data dissemination, time synchronization, key distribution, node localization, and routing. On the other hand, sensors are prone to failure such as exhaustion of energy, environmental hazards, and software or hardware malfunctioning. In this paper, we make an enhancement of the latest proposed relay-based broadcasting method by considering a trust index model to achieve a fault tolerant relay node selection. In addition, Formal Concept Analysis is used instead of the linear function. The effectiveness of the proposed scheme is confirmed through a simulation study using NS-2.