Really Useful Rusty! is a magazine story.
Harold the helicopter is often patrolling the skies above the little railway. One day, he rescues a couple of stranded hikers and tells Rusty when they meet. Harold doesn't think Rusty is very useful at all. That night, a storm rages across the Skarloey Railway. In the morning, there is a lot of damage for Rusty to put right. Then he notices that the pleasure boat has sunken in the lake. Harold can't lift it out because it's too heavy but Rusty tows it to the shore where a crane lifts it onto a lorry. Harold doesn't think Rusty is useless now.