MAR Consulting AS facilitated and documented an extensive failure mode, effects and criticality analysis (FMECA) on the hydraulic system of a blow-out preventer (BOP). The methodology was based on IEC60812 but modified towards operability and functionality of the system in analysis. The main purpose was to utilize the experience and knowledge of the participants to produce ready-made in-service risk assessments of failures that can occur. All components and failure modes were systematically assessed during the 45-days workshop in Houston, USA. The resulting assessments are to be integrated into a built for purpose simulation software delivered by a third-party. The objective is to support the drilling contractors’ decision making towards the operator and regulators when failures occur during service.