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 the opposite direction. if you jam the secondary valve just slightly off neutral, you could cause the valves to basically misalign and import hydraulic fluid in the wrong direction so the rudder reversed operation. this would be like driving your car and you turn to the left and the car goes right. you ll never figure this out before the car goes off the road. investigators had found a lethal malfunction in a valve the size of a pencil capable of bringing down a boeing 737. the malfunction leaves no marks or scars, almost as if it never happened, matching exactly what investigators found in u.s. air 427. all of a sudden you put the reversal scenario in and it all started coming together that all these parts now fit. the big puzzle we ve had the edges and everything else, now the center pieces are all locking in. when flight 427 s crew encountered the wake turbulence of a passing airplane, they press down on the rudder pedals to counter the wake an
the opposite direction. if you jam the secondary valve just slightly off neutral, you could cause the valves to basically misalign and import hydraulic fluid in the wrong direction so the rudder reversed operation. this would be like driving your car and you turn to the left and the car goes right. you ll never figure this out before the car goes off the road. investigators had found a lethal malfunction in a valve the size of a pencil capable of bringing down a boeing 737. the malfunction leaves no marks or scars, almost as if it never happened, matching exactly what investigators found in u.s. air 427. all of a sudden you put the reversal scenario in and it all started coming together that all these parts now fit. the big puzzle we ve had the edges and everything else, now the center pieces are all locking in. when flight 427 s crew encountered the wake turbulence of a passing airplane, they
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