Boeing 737 Rudder Control System Malfunction Due to Moisture Intrusion

In February 2024, a United Airlines Boeing 737 Max experienced rudder pedal failure, with the pedals becoming stuck in a neutral position during landing. Although the incident did not result in injuries, it prompted an investigation that revealed the presence of moisture inside the rudder control system’s actuators, which could freeze and impede functionality. The NTSB found that over 353 actuators manufactured by Collins Aerospace since 2017 were potentially affected due to incorrect assembly of sealed bearings. As a result, the NTSB has recommended that the Federal Aviation Administration (FAA) assess whether these actuators should be removed from service until replacements can be provided. This situation adds to ongoing challenges for Boeing, which has faced increased scrutiny and regulatory pressures following previous incidents involving the 737 Max.

Key Findings

• Incident Overview: The NTSB’s investigation stemmed from a February 2024 incident where rudder pedals on a United Airlines flight became non-functional during landing, requiring the captain to rely on alternative steering methods.

• Moisture Intrusion: The primary issue identified was moisture accumulation within the actuators, which can freeze and obstruct rudder control, significantly impacting aircraft safety.

• Regulatory Response: The NTSB has directed Boeing to inform airlines about potential pilot responses in the event of similar malfunctions and to alert them about the risk of actuator failure due to cold weather conditions.

• Industry Impact: Over 40 foreign airlines have been warned that their Boeing 737 fleets may be using potentially faulty rudder components, with a total of 271 parts identified as at risk of failure.

This situation underscores ongoing concerns regarding the safety and reliability of the Boeing 737, particularly as the aircraft faces heightened scrutiny from regulators and the public.