Cool things with wheels since 2006
No wonder it's pretty rare thing. They are unnecessary risk on landing so only on such rare photo you can see them under heli. I remember a photo of Little Bird with underbelly tank on Alaska and I did even found the article with photo of it. http://icestories.exploratorium.edu/dispatches/to-capture-a-polar-bear/index.html
What an odd looking helicopter this thing was. It looks like its back is broken when sitting on the ground.