USAir Flight 427

USAir Flight 427

N513AU, the aircraft involved in the accident, in 1991
Accident
Date	September 8, 1994 (1994-09-08)
Summary	Loss of control due to rudder hardover[1]
Site	Hopewell Township, Beaver County, Pennsylvania, United States 40°36′14″N 80°18′37″W / 40.60393°N 80.31026°W / 40.60393; -80.31026
Aircraft
Aircraft type	Boeing 737-3B7
Operator	USAir
IATA flight No.	US427
ICAO flight No.	USA427
Call sign	USAIR 427
Registration	N513AU[2]
Flight origin	O'Hare International Airport, Chicago, Illinois, United States
Stopover	Pittsburgh International Airport, Moon Township, Pennsylvania, United States
Destination	Palm Beach International Airport, Palm Beach County, Florida, United States
Occupants	132
Passengers	127
Crew	5
Fatalities	132
Survivors	0

USAir Flight 427 was a scheduled flight from Chicago's O'Hare International Airport to Palm Beach International Airport, Florida, with a stopover at Pittsburgh International Airport. On Thursday, September 8, 1994, the Boeing 737 flying this route crashed in Hopewell Township, Pennsylvania while approaching Runway 28R at Pittsburgh, which was USAir's largest hub at the time.

This accident was the second longest air crash investigation in history. The investigation into USAir 427 helped to also solve the crash of United Airlines Flight 585. The National Transportation Safety Board (NTSB) determined that the probable cause was that the aircraft's rudder malfunctioned and went hard over in a direction opposite to that commanded by the pilots, causing the plane to enter an aerodynamic stall from which Captain Peter Germano and First Officer Charles B. Emmet III were unable to recover. All 132 people on board were killed, making the accident the deadliest air disaster in Pennsylvania's history. The reports indicated that hot hydraulic fluid entering the rudder's dual servo valve froze, causing the rudder to work in the opposite direction.