Introduction : Following the reporting of an occupational accident that occurred in a cement plant and resulted in the death of two workers during a cement unblocking operation, we conducted an investigation whose objective is to identify the causes and factors that led to the accident and prevent other possible accidents. Method: the method used in analyzing the accident is the fault tree analysis conducted immediately after the accident. The facts were gathered concerning the individual, the task performed, the equipment used, and the work environment. Results: The accident, which occurred two and a half hours (2:30) after the start of the shift, caused two victims who were buried under tons of cement. Their activity consisted of almost manually removing the cement stuck to the walls of the silos. The fault tree analysis highlights factors related to the environment and tools. The individual factor, essentially linked to the professionalism and expertise of the construction manager, is also implicated. Conclusion: The occurrence of this accident has a multifactorial origin, particularly work organization and negligence of risks, and to avoid other accidents we favor evaluating situations before intervention and periodic maintenance of work facilities.

Keywords: cement silo maintenance and cleaning, cement silos, cement unblocking,  fault tree analysis method