ROANOKE TIMES
Copyright (c) 1997, Roanoke Times
DATE: Friday, February 21, 1997 TAG: 9702210059
SECTION: NATIONAL/INTERNATIONAL PAGE: A-1 EDITION: METRO
SOURCE: Associated Press
WASHINGTON
THE RUDDER CONTROL ON Boeing 737s is suspected as a cause of crashes. The design should be changed more quickly, says a national safety board.
Federal safety investigators are stepping up pressure to redesign the rudder controls on Boeing 737s, the world's most widely used airliner. Control problems are suspected in a pair of deadly crashes.
The National Transportation Safety Board called Thursday for a speedup in the control redesign and urged additional training for flight crews in dealing with sudden rolls caused by unexpected rudder movement.
In particular, the board said, crews should be warned that under certain conditions the plane's rudder can reverse itself. The rudder is the large movable surface on the tail of an airplane that controls left-and-right movement.
Recent tests indicate that the jamming of a control valve leading to sudden reverse rudder ``during normal pilot response can no longer be considered an extremely improbable or an extremely remote event,'' the safety board reported.
There ``is no history of a rudder reversal in flight,'' responded Tom McSweeny, the Federal Aviation Administration's director of aircraft certification.
Boeing spokeswoman Susan Bradley said the company is ``already working to an aggressive schedule and would do everything we could to cooperate'' with authorities.
The safety board investigates accidents but has no enforcement authority. Its recommendations were in a letter to the FAA, which sets aviation safety standards.
The move may indicate the safety board is getting closer to blaming the rudder in the crash of USAir Flight 427 on Sept. 8, 1994. The plane dived into a ravine on its approach to Pittsburgh International Airport, killing all 132 people aboard.
Investigators have studied that case intensely. A similar problem is suspected in the 1991 crash of United Airlines Flight 585 at Colorado Springs, Colo., killing all 25 aboard.
Other cases of unexpected rudder movement on 737s are also being investigated, including an incident last June 9 when Eastwind Airlines Flight 517 experienced an unexpected roll on approach to Richmond, Va., International Airport. The pilots were able to recover and there were no injuries.
On Jan. 16, Boeing and the FAA announced plans to redesign the rudder power control units for 737s to prevent jamming or reversal of the rudders. It has also directed rudder inspections every 2,500 hours of flight time.
The FAA said at that time it planned to issue an airworthiness directive requiring all 737s to be retrofitted within two years.
The safety board's new recommendation calls on the FAA to speed up that process. Recent tests, the board said, ``indicate the current Boeing B-737 rudder system does not provide the same level of safety as on similar transport category airplanes.''
McSweeny called the two-year timetable for replacement of the rudder power control units ``aggressive,'' considering that new equipment has to be designed and tested.
Worldwide, there are 2,705 of the twin-engine jets flying, including 1,115 in the United States.
LENGTH: Medium: 66 linesby CNB