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NTSB · Safety Recommendation

Safety Recommendation A-24-030

Recommendation

TO THE FEDERAL AVIATION ADMINISTRATION: If you determine the Collins Aerospace SVO 730 rudder rollout guidance actuators with incorrectly assembled bearings should be removed, notify international regulators that oversee operators of Boeing 737 airplanes about the safety issues involving the SVO-730 rudder rollout guidance actuator and encourage them to require the removal of actuators with incorrectly assembled bearings from 737NG and 737MAX airplanes until an acceptable replacement actuator becomes available for installation. (Urgent)

Safety Issue and Context

The National Transportation Safety Board (NTSB) is providing the following information to urge The Boeing Company and the Federal Aviation Administration (FAA) to take immediate action on the safety recommendations in this report concerning the potential for a jammed or restricted rudder control system on certain Boeing 737 airplanes. We identified these issues during our ongoing investigation of the rudder pedal anomaly involving a Boeing 737-8, N47280, while landing at Newark Liberty International Airport (EWR), Newark, New Jersey, on February 6, 2024.

On the basis of the results of postincident testing conducted in July 2024 and information from Boeing and Collins Aerospace, the NTSB is concerned that Boeing’s mitigation to overcome a jammed or restricted rudder control system during landing could also result in a large input to the rudder pedals and a sudden, large and undesired rudder deflection sufficient to cause loss of control or departure from the runway.

A jammed or restricted rudder scenario could become even more concerning if a high crosswind or an engine-out condition were simultaneously occurring with a jammed or restricted rudder, not only because the amount of rudder available to respond to these conditions might be insufficient to maintain control of the airplane if the jam is not cleared—but also because excessive rudder input may result if the jam is cleared by responding with Boeing’s mitigation. As a result, the NTSB is issuing two urgent safety recommendations to The Boeing Company and two urgent safety recommendations to the FAA.

Response History

March 30, 2026 · Recipient Response · FAA

The FAA continues to support the NTSB's ongoing investigation. The FAA will evaluate any new information and determine if additional actions are necessary.

June 17, 2025 · NTSB Correspondence · FAA

We understand that the FAA corrective action review board (CARB) reviewed available technical data and performed a safety risk analysis. The CARB concluded that this safety issue does not warrant short-term mandatory action at this time. We also note that, on October 7, 2024, the FAA published the following documents: • Safety Alert for Operators (SAFO) 24006, Potential for Jammed or Restricted Rudder on Boeing Model 737 Series Airplanes Equipped with Optional Collins Aerospace SVO-730 RRGA, which is intended to raise operator and flight crew awareness about this safety issue.

• Continued Airworthiness Notification to the International Community (CANIC), which notified international regulators that oversee operators of affected Boeing 737 airplanes about this safety issue.

Additionally, the FAA said it is reviewing data from a simulator evaluation that Boeing conducted on October 10, 2024, along with any new data that might be discovered during our ongoing investigation, to determine if mandatory actions are warranted.

On May 8, 2025, FAA staff informed NTSB staff that the CARB had reviewed the data from the October 2024 simulator evaluation and, as a result, the FAA did not intend to conduct any additional reviews. However, we remain concerned about this safety issue, which is also the subject of one of our open investigations. Because we are still reviewing information to determine if the FAA has sufficiently addressed these recommendations, we will reevaluate the FAA’s actions and classify these recommendations in our final report. In the meantime, the Board has voted to keep Safety Recommendations A-24-29 and -30 classified OPEN-- INITIAL RESPONSE RECEIVED.

October 28, 2024 · Recipient Response · FAA
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Recommendation Facts

Status
Open - Initial Response Received
Issued
September 26, 2024
Priority
CLASS I
Recipient
FAA
Adopted
September 26, 2024
Related Investigation
DCA24LA094
Related Report
AIR-24-06

-From Michael G. Whitaker, Administrator: The FAA has reviewed these urgent recommendations. On Thursday, September 26, the FAA held a Corrective Action Review Board (CARB) with relevant technical subject matter experts. The CARB reviewed the available technical data, safety risk analysis, and the Board’s report, AIR-24-06. Based on this information, the CARB concluded that the rudder issue does not warrant short-term mandatory action at this time, such as an Airworthiness Directive.

Given the urgency of the recommendations provided by the board and out of an abundance of caution, on October 7, the FAA issued Safety Alert for Operators (SAFO) 24006, Potential for Jammed or Restricted Rudder on Boeing Model 737 Series Airplanes Equipped with Optional Collins Aerospace SVO-730 Rudder Rollout Guidance Actuators (RRGA). Also on October 7, the FAA has issued a Continued Airworthiness Notification to the International Community (CANIC). On October 10, Boeing conducted a simulator evaluation. The FAA and the Board participated in the evaluation.

The FAA will analyze the data from the simulator evaluation as well as any new data discovered during the investigation to re-evaluate if mandatory actions are necessary. This information will also support the FAA’s response to the Board’s recommendations.

I will keep the Board informed of the FAA’s progress on these safety recommendations, and the FAA will continue to support the Board in their investigation of this matter.

September 26, 2024 · NTSB Correspondence · FAA

This letter provides information about the National Transportation Safety Board’s (NTSB) September 26, 2024, report Mitigate Safety Concerns Involving Boeing 737 Airplanes with Collins Aerospace SVO-730 Rudder Rollout Guidance Actuators (NTSB/AIR-24-06). The details of this ongoing incident investigation and the resulting urgent safety recommendations may be found in the attached report, which can also be accessed at http://www.ntsb.gov.

As a result of the NTSB’s preliminary findings in this investigation, we identified the following safety issues:

• the potential for jammed or restricted rudder systems on Boeing 737NG and 737MAX airplanes due to incorrectly assembled Collins Aerospace SVO-730 rudder rollout guidance actuators that allow moisture to accumulate and freeze; • the potential for uninformed flight crews of affected Boeing 737NG and 737MAX airplanes to apply rudder pedal force in an attempt to clear a jammed or restricted rudder control system but that also results in a large, sudden, and undesired input to the rudder and loss of airplane control; and

• the need to determine and disseminate guidance on appropriate flight crew responses if the affected Collins actuators on Boeing 737NG and 737MAX airplanes become jammed or restricted in flight or during landing.

Accordingly, the NTSB makes the following urgent safety recommendations to the FAA:

• Determine whether Collins Aerospace SVO-730 rudder rollout guidance actuators with incorrectly assembled bearings should be removed from Boeing 737NG and 737MAX airplanes and, if so, direct US operators to remove the actuators until acceptable replacement actuators become available for installation. (A 24 29) (Urgent)

• If you determine the Collins Aerospace SVO-730 rudder rollout guidance actuators with incorrectly assembled bearings should be removed, notify international regulators that oversee operators of Boeing 737 airplanes about the safety issues involving the SVO-730 rudder rollout guidance actuator and encourage them to require the removal of actuators with incorrectly assembled bearings from 737NG and 737MAX airplanes until an acceptable replacement actuator becomes available for installation. (A-24-30) (Urgent)

The NTSB is vitally interested in these urgent recommendations because they are designed to prevent accidents and save lives. We would appreciate a response within 30 days of the date of this letter, detailing the actions you have taken or intend to take to implement these urgent recommendations. When replying, please refer to the safety recommendations by number (Safety Recommendations A-24-29 and A-24-30). We encourage you to submit your response to ExecutiveSecretariat@ntsb.gov. If your reply, including attachments, exceeds 20 megabytes, please e mail us at the same address for instructions on how to send larger documents.

Please do not submit both an electronic copy and a hard copy of the same response.

The attached letter from the NTSB Chair provides information about the Mitigate Safety Concerns Involving Boeing 737 Airplanes with Collins Aerospace SVO-730 Rudder Rollout Guidance Actuators (AIR-24-06). The details of this accident investigation and the resulting safety recommendations may be found in the attached report, which can also be accessed at http://www.ntsb.gov.

The NTSB is vitally interested in these recommendations because they are designed to prevent accidents and save lives. We would appreciate a response within 30 days of the date of this letter detailing the actions you have taken or intend to take to implement these urgent recommendations. When replying, please refer to the safety recommendations by number (for example, A-24-29 and A-24-30. We encourage you to submit your response to ExecutiveSecretariat@ntsb.gov. If your reply exceeds 20 megabytes, including attachments, please e mail us at the same address for instructions on how to send larger documents. Please do not submit both an electronic copy and a hard copy of the same response.

From the aviation investigation report Safety Concerns Involving Boeing 737 Airplanes with Collins Aerospace SVO-730 Rudder Rollout Guidance Actuators (AIR-24-06):

Background and Analysis On February 6, 2024, about 1555 eastern standard time, the flight crew of United Airlines flight 1539, a Boeing 737-8, N47280, experienced a rudder pedal anomaly while landing at EWR. In a postincident statement, the captain reported that, during the landing rollout, the rudder pedals were “stuck” in their neutral position and did not move in response to the “normal” application of foot pressure to maintain alignment with the runway centerline. The flight was operating under the provisions of Title 14 Code of Federal Regulations Part 121 as a scheduled international passenger flight from Lynden Pindling International Airport, Nassau, Bahamas, to EWR.

According to data derived from the flight data recorder, the flight crew applied approximately 32 pounds of force to the rudder pedals before touchdown which yielded no discernible effect on the rudder position or heading. The flight crew attempted to clear the jammed rudder controls immediately after touchdown, applying approximately 75 pounds of force to the rudder pedals when the airspeed was about 120 knots, again with no effect on the rudder position or heading.

With the airplane’s airspeed continuing to decrease during rollout, the flight crew applied approximately 42 pounds of force to the pedals, but the jam persisted. The captain elected instead to use the nosewheel steering tiller as the airplane slowed to a safe taxi speed. The captain stated that, after the airplane entered the assigned taxiway, he asked the first officer to check the rudder pedals on his side of the flight deck, and the first officer indicated that the same anomaly was occurring.

Data derived from the flight data recorder indicate that shortly after, with the airplane traveling at a groundspeed of less than 20 knots, the flight crew applied approximately 59 pounds of force on the rudder pedals, and the rudder pedals and rudder surface began to operate normally. The airplane taxied to the gate without further incident, and all airplane occupants (2 flight crewmembers, 4 cabin crewmembers, and 155 passengers) deplaned without any injuries or damage to the airplane.

United Airlines received the incident airplane from Boeing on February 20, 2023. The airplane was equipped with a Collins Aerospace SVO-730 rudder rollout guidance actuator, which was electrically disabled based on the operator’s delivery requirements for the autoflight system. Although the actuator was disabled, it remained mechanically connected to the upper portion of the airplane’s aft rudder input torque tube by the actuator’s output crank arm and a pushrod, as shown in figure 1.

Postincident examination and testing of the incident SVO-730 rudder rollout guidance actuator found that the torque needed to rotate the actuator’s output crank arm was 2.8 inch pounds at room temperature; this torque value was within specified design limits. After the actuator was subjected to cold temperatures in a chamber for 1 hour, the output crank arm could not be rotated at the previous torque value. Increases in torque were incrementally applied. The torque needed for the output crank arm to start rotating was 520 inch pounds, which significantly exceeded the specified design limits.

Once the output crank arm started rotating, a torque of about 100 inch-pounds was required to sustain the rotation; this torque value also exceeded the specified design limits. Disassembly of the actuator revealed evidence of moisture within the unit, as shown in figure 2, which would account for the resistance observed in excess of specified design limits.

Afterward, three additional SVO-730 rudder rollout guidance actuators were examined and tested in the same manner (cold soaking) as the inc