One year after Boeing agreed to redesign rudder-control systems on nearly 2,000 737 jets, the Federal Aviation Administration (FAA) recently required U.S. carriers to install the redesigned rudder system on all 737 aircraft. The new design includes dual hydraulic valves and several other adjustments that will significantly reduce uncommanded rudder movements by the pilot.

The National Transportation Safety Board (NTSB) has called for the modifications for several years. The FAA estimates the changes, which foreign carriers plan to implement in the near future, will cost over $360 million. Two fatal 737 crashes have been attributed to rudder failure.