In the finals of the 2012 Winter X Games Best Snowmobile Trick event, Justin Hoyer attempted a double backflip on his first run of the night, but it didn't turn out well.
Hoyer made a couple of approaches to the ramp before he finally decided to give it his all. And it was close as you can see in the video. But he didn't have near enough speed and he had his snowmobile crash head first into the ground before the second flip could be completed.
Hoyer did get up and walk around a bit before he realized that his right arm was injured and flying in the open air.
Levi LaVallee tried the same trick in 2009, but he did land it completely as he came off his sled on the landing. He, however, came away without injury.