What is the position of HD Heads during a spin down?
The heads are parked out of the way. See http://en.wikipedia.org/wiki/Hard_disk_drive#Landing_zones_and_load.2Funload_technology, specifically:


  Modern HDDs prevent power interruptions or other malfunctions from landing its heads in the data zone by either physically moving (parking) the heads to a special landing zone on the platters that is not used for data storage, or by physically locking the heads in a suspended (unloaded) position raised off the platters.