Variants of a mold are catalogued separately, so each one has its own sets and minifigs. Check these too if something you expect is missing here.

• 41531 Technic Cylinder 4 x 4 with Pin Holes and Centre Bar, Closed Sides on Bar this part is a mold of it
• 46667 Jet Engine Fan with 10 Blades and Technic Pin this part is a pair of it