NTSB issues 'urgent' safety alert for Boeing 737 rudder system

The National Transportation Safety Board (NTSB) issued urgent safety advisories to Boeing and the Federal Aviation Administration (FAA) on Thursday in response to the possibility of a stall or limited rudder control on some 737 Next-Generation and 737 Max 8 aircraft.

The rudder controls the sideways movement of the aircraft's nose, also known as yaw motion.

The agency is currently investigating a February incident in which the rudder pedals of a United Airlines Boeing 737 Max 8 became “stuck” in their neutral position while landing at Newark Liberty International Airport in New Jersey.

At that point, the captain had to rely on the nosewheel tiller to control the plane's direction after landing, the NTSB said.

The pilots reported that the plane was able to taxi to the gate “without further incident” and all 155 passengers and six crew members were able to eject. No injuries were reported.

As part of the investigation, NTSB investigators tested one of the accident aircraft's rudder control components at the component's manufacturer, Collins Aerospace.

After testing in a cold environment, researchers found that the component's function was “significantly impaired.” Subsequently, Collins Aerospace discovered that the component had been incorrectly assembled during production.

As part of the Boeing 737 flight manual, pilots with a blocked or restricted rudder system are instructed to “overwhelm the blocked or restricted system.” [using] maximum force, including a combined effort from both pilots.”

However, NTSB investigators raised concerns that this force applied during landing or taxiing “could result in heavy application of the rudder pedals and a sudden, large and undesirable rudder deflection that could inadvertently result in loss of control or runway departure.” “. ”

In its recommendations, the agency recommended that the aircraft manufacturer determine “in addition to the use of maximum pedal force, appropriate flight crew responses” for such situations during flight or landing.