Download or read book AIR CRASH INVESTIGATIONS: JAMMED RUDDER KILLS 132, The Crash of USAir Flight 427 written by Hank Williamson, editor and published by Lulu.com. This book was released on 2011-10 with total page 561 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Boeing 737 has a history of rudder system-related anomalies, including numerous instances of jamming. A number of accidents and incidents were the result of the airplanes' unexpected movement of their rudders. During the course of the four and a half year investigation of the crash of USAir Flight 427 near Aliquippa, Pennsylvania, killing 132 people, the NTSB discovered that the PCU's dual servo valve could jam as well as deflect the rudder in the opposite direction of the pilots' input, due to thermal shock, caused when cold PCUs are injected with hot hydraulic fluid. This finally solved the mystery of sudden jamming of the rudders of this aircraft.