On September 8 , 1994 , USAir Flight 427 , a Boeing 737-300 , crashed near Pittsburgh , Pennsylvania . While on approach to Pittsburgh International Airport , Flight 427 suddenly rolled to the left . Although the pilots were briefly able to roll right and level the plane , it rolled left a second time and the pilots were unable to recover . The resulting crash killed all 132 people on board . The NTSB realized early into its investigation that the crash of Flight 427 might have been caused by an unintended or uncommanded rudder movement , similar to the suspected ( but not yet established ) cause of the Flight 585 crash . As a result , the NTSB conducted additional testing on United Flight 585 's PCU servo during its Flight 427 investigation
USAir Flight 427
USAir Flight 427
Boeing 737 rudder issues