In safety-critical, networked embedded systems, it is important that the way in which a fault(s) in one component of the system can propagate throughout the system to other components is analyzed correctly. Many real-world systems, such as modern aircrafts and automobiles, use large-scale networked embedded systems with complex behavior. In this work, we have developed techniques and a software tool, FauPA, that uses those techniques to automate fault-propagation analysis of large-scale, networked embedded systems such as those used in modern aircraft. This work makes three main contributions. 1. Fault propagation analyses. We developed algorithms for two types of analyses: forward analysis and backward analysis. For backward analysis, we developed two techniques: a naive algorithm and an algorithm that uses Datalog. 2. A system description language. We developed a language that we call Communication System Markup Language (CSML) based on XML. A system can be specified concisely and at a high-level in CSML. 3. A GUI-based display of the system and analysis results. We developed a GUI to visualize the system that is specified in CSML. The GUI also lets the user visualize the results of fault-propagation analyses.