FAA issues Boeing 737 safety directive
November 1, 1996
WASHINGTON (CNN) -- The FAA on Friday issued an emergency airworthiness directive for the Boeing 737 rudder "power control unit," suspected as a factor in several unsolved deadly crashes.
Airlines flying the 737, the world's most widely-used jetliner, will have ten days from the date they receive the order to perform the inspections and make any necessary repairs.
Sources told CNN that the National Transportation Safety Board experts were able to reproduce a situation in which the power control unit would jam, forcing the rudder into a so called "hard over", meaning the tail rudder jams to the left or right.
The problem has only been re-produced under laboratory conditions and is extremely rare, the sources stressed.
"Hard-overs" are suspected in the unexplained crashes of 737's in Colorado Springs and Pittsburgh, although it has not been positively linked to the accidents.
Earlier this month, the NTSB recommended a major overhaul of the tail rudder system in the 737. The recommendations required retrofitting existing planes and redesigning new ones to prevent possible loss of control from rudder failures. There are about 2,800 Boeing 737s in service.
The list of safety proposals would require Boeing to develop and install cockpit indicators that would provide details on rudder position and movements.
The NTSB also has recommended that Boeing 737 flight crews be better trained to deal with uncontrolled rolls, a practice some airlines have adopted.
If the full range of revisions is required, they could cost the airline industry tens of millions of dollars.
Boeing spokesman Tim Neale has said the rudder system already has been redesigned for newer-model 737s now in production. The design change was needed because the aircraft is bigger than older models, not because of safety concerns, he said.Correspondent Carl Rochelle contributed to this report
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