Enhancing FMECA(XMECA)-based Safety Assessment Considering Criticality of Assumptions and Analysis Errors

The increasing complexity of safety-critical instrumentation and control systems (I&C) has led to the adoption of semi-formal assessment methods that integrate expert-based and risk-oriented approaches with mathematical reliability tools. One prominent method in this field is FMECA (Failure Modes, Effects, and Criticality Analysis), which has evolved over decades and given rise to various specialized forms, collectively known as XMECA, where "X" may denote failure, intrusion, or events specific to safety and security concerns. However, FMECA applications are limited by significant reliance on expert judgment, raising concerns about assessment accuracy and consistency. The study discusses these limitations and provides an approach intended to reduce expert assumptions and analysis errors. The results of assessing their impact on trustworthiness of FMECA safety analysis are discussed considering expert-based evaluation and taking into account types of questions and experience.