Rework the text to have better logic.
Modern turbines usually have a small onboard crane for hoisting maintenance tools and minor components. Large heavy components like generator, gearbox, blades and so on are rarely replaced and a heavy lift external crane is needed in those cases.
Modern turbines usually have a small onboard crane for hoisting maintenance tools and minor components. However, large heavy components like generator, gearbox, blades and so on are rarely replaced and a heavy lift external crane is needed in those cases.