across these openings it redirects fluid. >> in the days after the u.s. air accident, investigators recovered the flight 427's pcu from the crash site. >> some is intact. some of the brackets broken. >> if something did malfunction inside this pcu, it left no evidence. >> the valves were not badly scarred. there were no marks. there wasn't an instant indication of what would have caused the power control unit to have problems. >> investigators run a battery of tests on the pcus from u.s. air 427 and eastwind airlines, trying to determine if the units can jam. what they find is even more alarming. not only can the pcu jam, but it can then deflect the rudder in