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Safety Recommendation Details

Safety Recommendation A-99-025
Details
Synopsis: On 9/8/94, about 1903:23 eastern daylight time, USAir (now US Airways) flight 427, a Boeing 737-3B7 (737-300), N513AU, crashed while maneuvering to land at Pittsburgh Int'l. Airport, Pittsburgh, PA. Flight 427 was operating under the provisions of 14 code of federal regulations (CFR) part 121 as a scheduled domestic passenger flight from Chicago-O'Hare Int'l. Airport, Chicago, Il, to Pittsburgh. The flight departed about 1810, with 2 pilots, 3 flight attendants, and 127 passengers on board. The airplane entered an uncontrolled descent and impacted terrain near Aliquippa, PA. All 132 people on board were killed, and the airplane was destroyed by impact forces and fire. Visual meteorological conditions prevailed for the flight, which operated on an instrument flight rules flight plan.
Recommendation: TO THE FEDERAL AVIATION ADMINISTRATION: Require all 14 Code of Federal Regulations part 121 air carrier operators of the Boeing 737 to provide their flight crews with initial and recurrent flight simulator training in the "uncommanded yaw or roll" and "jammed or restricted rudder" procedures in Boeing's 737 operations manual. The training should demonstrate the inability to control the airplane at some speeds and configurations by using the roll controls (the crossover airspeed phenomenon) and include performance of both procedures in their entirety. (Supersedes Safety Recommendation A-96-107, A-96-109, A-96-112, and A-96-113)
Original recommendation transmittal letter: PDF
Overall Status: Closed - Acceptable Action
Mode: Aviation
Location: ALIQUIPPA, PA, United States
Is Reiterated: No
Is Hazmat: No
Is NPRM: No
Accident #: DCA94MA076
Accident Reports: Uncontrolled Descent and Collision With Terrain, USAir Flight 427, Boeing 737-300, N513AU
Report #: AAR-99-01
Accident Date: 9/8/1994
Issue Date: 4/16/1999
Date Closed: 1/3/2002
Addressee(s) and Addressee Status: FAA (Closed - Acceptable Action)
Keyword(s): Rudder,Simulator,Training and Education

Safety Recommendation History
From: NTSB
To: FAA
Date: 1/3/2002
Response: The Safety Board is pleased that the FAA has issued FSAT 00-16A and FSGA 00-09A and believes this action largely meets the wording of recommendation A-99-25. Accordingly, Safety Recommendation A-99-25 is classified "Closed--Acceptable Action." However, as indicated in our previous correspondence the Board remains concerned that the training procedures specified in the FSAT and the FSGA may not prepare flightcrews to maintain control of a Boeing 737 in the event of a hardover rudder malfunction occurring at low altitudes during takeoffs, landings, and during high-speed runway operations. A rudder malfunction is more probable when using the rudder very quickly to its full authority-which is the case with an engine failure, either on takeoff or landing. Further, there is a crossover speed for every flap position. The Board believes the FAA should have required that these issues be addressed in the Boeing 737 training for uncommanded yaw or roll and jammed or restricted rudder procedures. Given these concerns, the Board will continue to monitor rudder events on the Boeing 737 fleet.

From: FAA
To: NTSB
Date: 10/1/2001
Response: Letter Mail Controlled 10/05/2001 12:57:13 PM MC# 2010796: On December 11, 2000, the Federal Aviation Administration (FAA) issued Joint Flight Standards Information Bulletin for Air Transportation (FSAT) 00-16A and General Aviation (FSGA) 00-09A, AD 2000-22-02, B737 Uncommanded Rudder. The bulletin directs all flight standards district offices, certificate management offices, and principal operations inspectors to ensure that all 14 CFR Part 121 air carrier operators of Boeing 737 airplanes provide their flightcrews with initial and recurrent flight simulator training in the uncommanded yaw or roll and jammed or restricted rudder procedures contained in Boeing's 737 Operations Manual. The training will demonstrate the inability to control the airplane at some speeds and configurations by using the roll controls (the crossover airspeed phenomenon) and include performance of both procedures in their entirety. A copy of the bulletin was provided to the Board on February 27, 2001. On June 14, 2001, the Board classified this safety recommendation in an "open-- acceptable" status stating that while the FAA had taken appropriate action, the Board remains concerned that the procedures may not prepare flightcrews to maintain control of a Boeing 737 in the event of a hardover rudder malfunction occurring at low altitudes while taking off and landing or during high-speed runway operations. The FAA is convinced that the probability of a hardover rudder malfunction occurring at low altitudes while taking off and landing or during high-speed runway operations is extremely remote. On takeoff, a rudder hardover during the time between a controls check (usually just prior to taking the active runway) and reaching 1,000 feet 60 to 90 seconds later has an occurrence rate lower than 10-9. The FAA and Board representatives noted that full rudder capability is required to deal with the much higher probability of an engine failure. On approach, landing, and rollout, the Boeing 737 has the following performance characteristic--as speed is reduced and flaps are extended, the lateral control system (ailerons and roll spoilers) becomes much more effective than the rudder, which loses effectiveness as speed is reduced. As a result, as flaps extend beyond about 10 degrees, the roll controls completely overpower the rudder, and a rudder hardover event is completely controllable. I believe that the actions outlined in the bulletin meet the intent of this safety recommendation pending the new rudder system being developed and installed in the applicable Boeing 737 models. I consider the FAA's action to be completed on this safety recommendation.

From: NTSB
To: FAA
Date: 6/14/2001
Response: The FAA is taking the action recommended; however, the Safety Board is concerned that the procedures established thus far, including those in AD-2000-22-02, may not prepare flight crews to readily maintain control of a 737 in the event of a hardover rudder malfunction occurring at low altitudes while taking off and landing or during high-speed runway operations. The Safety Board would appreciate learning how the FAA plans to address this concern. Pending the answer to this question, Safety Recommendation A-99-25 is classified "Open-Acceptable Response."

From: FAA
To: NTSB
Date: 2/27/2001
Response: Letter Mail Controlled 03/05/2001 3:54:31 PM MC# 2010187 On December 11, 2000, the Federal Aviation Administration (FAA) issued Joint Flight Standards Information Bulletin for Air Transportation (FSAT) 00-16A and General Aviation (FSGA) 00-09A, AD 2000?22-02, B737 Uncommanded Rudder. The bulletin directs all flight standards district offices, certificate management offices, and principal operations inspectors to ensure that all 14 CFR Part 121 air carrier operators of Boeing 737 airplanes provide their flightcrews with initial and recurrent flight simulator training in the uncommanded yaw or roll and jammed or restricted rudder procedures contained in Boeing's 737 Operations Manual. The training will demonstrate the inability to control the airplane at some speeds and configurations by using the roll controls (the crossover airspeed phenomenon) and include performance of both procedures in their entirety. I have enclosed a copy of the bulletin for the Board's information.

From: FAA
To: NTSB
Date: 6/25/1999
Response: Letter Mail Controlled 6/30/99 3:02:35 PM MC# 990699: The FAA is working with Boeing and the Board's staff to determine the scope and appropriate revision to the procedures for addressing a jammed or restricted rudder. It is anticipated that this project will result in a formal evaluation of the current procedures using the Boeing 737 M-cab engineering simulator. The FAA will take action to address the issues of this safety recommendation upon completion of the evaluation in response to Safety Recommendation A-99-24. I will keep the Board informed of the FAA's progress on this safety recommendation.