There is a board next to it explaining the significance of this poorly landed aircraft. It says, and I quote:
"Usually, Paola Pivi does the impossible, combines the incompatible, and confronts us with the unexpected. The helicopter Wessex 558 - placed upside down - challenges the audience's imagination: All of a sudden it appears impossible that this tinny jumbo could ever fly: an allegory to the fast-rising careerist looking for a solution to the hectic daily routine. Paola Pivi's concern is the miracle of flight, the force, appeal, and fascination of flying objects, but also how helpless and devastated they appear when they fail to serve their obvious purpose."
Here is a picture of the billboard in case you don't believe me:
