Is it normal for a cat to attack ceiling fans?

My cat, Psycho B**** (who I love dearly) sits for hours watching the fan. Her little head just goes round and round watching it. Kind of like in the Exorcist. Then she'll leap at it and grab one of the blades and spin around for a while until she gets thrown off. I think it's kind of amusing but now the fan wobbles and I had to replace the bedroom window twice now since she's been thrown threw it.