Fan blade on Dart broke today

I hauled my motor to my buddies shop today, so I have the motor and tranny there waiting to go into the Dart in a week and a half. The time was almost perfect. I could drop off my brother's truck, drive home, drop the Dart at my buddies shop and be there just in time for my wife to get off work and pick me up. Sweet! I was driving down the highway at 65 mph and I thought I had a flat tire. It was shaking badly. I pulled over and at idle it was shaking so violently I thought the dash was going to fall off. I shut it off, got out in rush hour traffic and popped the hood. The first thing I saw was the alternator belt was off. Then I see two blades from the fan lying on top of the power steering pump. How the hell does that happen? It was running very well considering it was only 40 degrees out.

View attachment Broken fan blade.jpg

View attachment Broken fan blade 1.jpg