NTSB Asks For Urgent Safety Checks On Boeing 737 Rudder System

In a latest blow to the struggling aerospace giant Boeing Co., which has been hit by an ongoing strike by machinists as well as various safety issues, the National Transportation Safety Board has issued urgent safety recommendations to Rudder control system on some 737 airplanes.

The warning has been given to Boeing and the Federal Aviation Administration or FAA in response to the potential for a jammed or restricted rudder control system on some B-737NG and 737MAX airplanes. These systems were supplied by component manufacturer Collins Aerospace.

The latest development follows NTSB’s investigation of a February 6, 2024 incident involving a faulty rollout guidance actuator of a United Airlines Boeing 737-8, a MAX variant.

More than 353 actuators that Collins had delivered to Boeing since February 2017 were affected by the issue.

In the February 6 incident of the United Airlines Boeing 737-8, the rudder pedals were “stuck” in their neutral position during the landing rollout at Newark Liberty International Airport, Newark, New Jersey.

The captain used the nosewheel steering tiller to control the airplane’s direction after touching down. There was no damage to the airplane or injuries to the 155 passengers and six crewmembers.

During the ongoing probe, NTSB investigators tested one of the rudder control components from the incident airplane, a rollout guidance actuator, at Collins Aerospace.

The rudder rollout guidance actuator, which is installed in the tail of some B-737NG and 737MAX airplanes, is designed to control the rudder’s movement during category IIIB approach, landing and rollout operations. The actuator remains mechanically engaged with the rudder system, although it is not used in non-precision landings.

The agency noted that the incident actuator and an identical unit from another airplane were tested in a cold environment, and the actuators’ function was significantly compromised. The investigators found evidence of moisture in both actuators, which failed the testing.

Following the testing, Collins determined that a sealed bearing was incorrectly assembled during production of the actuators, leaving the unsealed side more susceptible to moisture that can freeze and limit rudder system movement.

Boeing’s 737 flight manual instructs pilots confronted with a jammed or restricted rudder to “overpower the jammed or restricted system [using] maximum force, including a combined effort of both pilots.”

Meanwhile, this amount of force applied during landing or rollout could result in a large input to the rudder pedals and a sudden, large, and undesired rudder deflection that could unintentionally cause loss of control or departure from a runway, the NTSB warns.

Following the investigation, the NTSB has asked Boeing to determine appropriate flight crew responses besides applying maximum pedal force for such situations in flight or during landing.

The agency also urged that the plane maker notify flight crews operating 737s with affected actuators that the rudder control system can jam due to moisture that has accumulated inside the actuators and frozen. The FAA is also asked to determine if actuators with incorrectly assembled bearings should be removed from airplanes, and if so, to direct U.S. operators to do so until replacements are available.

Further, if the FAA determines the affected actuators should be removed, the NTSB has recommended to notify aviation regulators in other countries that oversee operators of B737 airplanes and to require them to remove the affected actuators until replacements are available.

The news comes amidst Boeing’s about 33,000 machinists union members continuing with their strike, which began on September 13, seeking better pay and benefits.

The strike, the first at the firm since 2008, has hit the commercial airplane production of the aircraft manufacturer, which is already struggling with its various plane safety issues.

Boeing was also planning various cost-cutting measures, including hiring freeze, cut in supplier spending and possible temporary furloughs, to meet the strike impact.