USAir Flight 427
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US Airways Flight 427 was a commercial airline flight from Chicago's O'Hare International Airport to Pittsburgh, Pennsylvania, with a final destination of West Palm Beach, Florida. The flight crashed on September 8, 1994, killing everyone on board.
On that day, the Boeing 737-3B7, registered N513AU, was approaching runway 28R in Pittsburgh's airport, which is located in Findlay Township, Pennsylvania. At about 6,000 feet (1,830 meters) and 6 miles {10 km) from the runway, the aircraft experienced a sudden loss of control and slammed into the ground in a nearly vertical position in Aliquippa, Pennsylvania, killing all 127 passengers and 5 crew members.
After its longest investigation in history—more than four and a half years—the concluding statement said:
- The National Transportation Safety Board determines that the probable cause of the USAir flight 427 accident was a loss of control of the airplane resulting from the movement of the rudder surface to its blowdown limit. The rudder surface most likely deflected in a direction opposite to that commanded by the pilots as a result of a jam of the main rudder power control unit servo valve secondary slide to the servo valve housing offset from its neutral position and overtravel of the primary slide. [1]
The NTSB concluded that similar rudder problems caused the previously mysterious March 31991 crash of United Flight 585, and the June 91996 incident involving Eastwind Airlines flight 517, both of which were Boeing 737s.
Other changes resulting from the investigation were:
- to warn and train pilots of insufficient aileron authority at an airspeed at or less than 190 knots (218 mph, 354 km/h), formerly the usual approach speed for a B737.
- to mandate four additional channels of information in flight data recorders, pilot rudder pedal commands
- Boeing redesigned the rudder system on 737s and retrofitted existing craft until the affected systems can be replaced
- Congress requires airlines to do a better job dealing with families of crash victims
External links
- NTSB Accident Investigation Docket
- AVweb article
- AVweb supplement
- Accident description on the Aviation Safety Network
Books
- Bill Adair, The Mystery of Flight 427: Inside a Crash Investigation, ISBN 1588340058
- Gerry Byrne, Flight 427: Anatomy of an Air Disaster, ISBN 038795256XTemplate:Aviation-stub