Safety analysis is increasingly important for a wide class of systems. In the automotive field, the recent ISO26262 standard foresees safety analysis to be performed at system, hardware, and software levels. Failure Modes and Effects Analysis (FMEA) is an important step in any safety analysis process, and its application at hardware and system levels has been extensively addressed in the literature. Conversely, its application to software architectures is still to a large extent an open problem, especially concerning its integration into a general certification process. The approach we propose in this paper aims at performing semi-automated FMEA on component-based software architectures described in UML. The foundations of our approach are model-execution and fault-injection at model-level, which allows us to compare the nominal and faulty system behaviors and thus assess the effectiveness of safety countermeasures. Besides introducing the detailed workflow for SW FMEA, the work in this paper focuses on the process for obtaining an executable model from a component-based software architecture specified in UML.