A failure in the bottom sheet of a bucket conveyor (KZBQ.AUMUND) during service was investigated. Sheets are coupled to the chain throught a screw connection; they operate in variable load scenarios causing fatigue. A chemical and microstructural analysis was made showing that sheet was built in steel with 0.15 % of Carbone without alloying elements that contribute to the refined grain and resistance increase. Strength calculation, used to determinate safety factor, consider load system and type material. Results concluded that geometry and thickness value do not provide an adequate fatigue resistance coefficient.