737-3B7usair With modified engines
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 at the time USAir's largest hub.
USAir Flight 427
USAir Boeing 737-3B7 at John Wayne Airport, Aug 1989.jpg
N513AU, the aircraft involved in the accident, in 1989
Accident
Date
September 8, 1994
Summary
Loss of control due to rudder hardover[1]
Site
Hopewell Township, Beaver County, near Pittsburgh International Airport, Pennsylvania, United States
40.60393°N 80.31026°W
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
Stopover
Pittsburgh International Airport
Destination
Palm Beach Int'l Airport
Occupants
132
Passengers
127
Crew
5
Fatalities
132
Survivors
0
737 rudder problem
During the 1990s, a series of issues affecting the rudder of Boeing 737 passenger aircraft resulted in multiple incidents. In two separate accidents, pilots lost control of their aircraft due to a sudden and unexpected rudder movement, and the resulting crashes killed everyone on board, 157 people in total.[1] Similar rudder issues led to a temporary loss of control on at least one other Boeing 737 flight before the problem was ultimately identified.
The National Transportation Safety Board determined that the incidents were the result of a design flaw that could result in an uncommanded movement of the aircraft's rudder.[2]:?13?[3]:?ix?
The issues were resolved after the Federal Aviation Administration ordered modifications for all Boeing 737 aircraft in service. In 2016, former NTSB investigator John Cox stated that time has proven the NTSB correct in its findings because no additional rudder-reversal incidents have occurred since Boeing's redesign.[4]
Sounds like Eastwind Airlines Flight 517
On June 9, 1996, while the NTSB's investigation of Flight 427 was still ongoing, the pilots of Eastwind Airlines Flight 517 briefly lost control of their aircraft, a 737-200, while flying from Trenton, New Jersey, to Richmond, Virginia.[2]:?ix? The aircraft experienced two episodes of rudder reversal while on approach to land in Richmond. Unlike the two prior incidents, the rudder issues on Flight 517 spontaneously resolved and the pilots were able to safely land the aircraft. One of the 53 people on board was injured.[3]:?51?
The NTSB investigated the Eastwind incident, and incorporated information from both United Flight 585 and Eastwind Flight 517 into its ongoing investigation of the Flight 427 crash.[3]:?44?
Other suspected 737 rudder PCU malfunctions
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The following Boeing 737 aircraft incidents were also suspected of being caused by a rudder PCU malfunction:
On June 6, 1992, Copa Airlines Flight 201, a 737-200 Advanced, flipped and crashed into the Darién Gap jungle, killing 47 people. Investigators initially believed that the airplane experienced a rudder malfunction, but after an exhaustive and extensive inquiry, they concluded that the crash was caused by faulty attitude indicator instrument readings.
On March 8, 1994, a Sahara Airlines aircraft that had three trainees and one supervising pilot on board crashed after performing a "touch-and-go landing" at New Delhi Airport and slammed into a Russian jet. The four pilots and five ground workers (a total of nine) were killed. Although repairs were done to the PCU with unauthorized parts, the incident is still thought to be in part due to the plane's rudder reversing both right and left.[9][10][11]
On April 11, 1994, a Continental Airlines pilot, Ray Miller, reported his aircraft rolled violently to the right and continued to pull to the right for another 18 minutes; the Boeing 737-300 landed safely. Continental removed the flight data recorder and rudder PCU from the incident aircraft and provided them to Boeing for investigation. Boeing concluded that the rudder had inadvertently moved due to an electrical malfunction, but only 2.5 degrees and for less than two minutes in total, a finding disputed by Miller.[9]
On February 23, 1999, MetroJet Flight 2710, a 737-200, experienced a slow deflection of the rudder to its blowdown limit while flying at 33,000 feet above Salisbury, Maryland. While a rudder malfunction was suspected, the aircraft was an older 737 and its flight data recorder only recorded 11 flight parameters, compared to the hundreds of parameters recorded by newer aircraft. NTSB chairman Jim Hall said that the investigation was "hampered by the lack of basic aircraft data."[12][13] All 112 passengers and five crew members (117 total) survived the incident.