'stuck' rudder pedal during landing roll out; Boeing 737 MAX 8
WASHINGTON (Reuters) - The National Transportation Safety Board (NTSB) said Thursday it is investigating a Feb. 6 United Airlines Boeing737 MAX 8 flight that experienced "stuck" rudder pedals during the landing rollout.
The NTSB said in a preliminary report the plane taxied to the gate at Newark Airport without incident and there were no injuries to the 161 passengers and crew. The captain said that during the landing rollout, the rudder pedals did not move in response to "normal" application of foot pressure while attempting to maintain the runway centerline.
The NTSB said in a preliminary report the plane taxied to the gate at Newark Airport without incident and there were no injuries to the 161 passengers and crew. The captain said that during the landing rollout, the rudder pedals did not move in response to "normal" application of foot pressure while attempting to maintain the runway centerline.
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Federal investigators said Thursday they confirmed pilots' account of a brief failure of rudder controls on a Boeing 737 Max after it landed at Newark Liberty International Airport in New Jersey last month.
United Airlines pilots said pedals that control rudder movement on the plane were stuck as they tried to keep the plane in the center of the runway during the Feb. 6 landing.
The pilots were able to use a small nose-gear steering wheel to veer from the runway to a high-speed turnoff. The rudder pedals began working again as the pilots taxied to the gate with 155 passengers and six crew members on the flight from Nassau, Bahamas, according to a preliminary report by the National Transportation Safety Board.
Boeing said this is the only rudder-response issue reported on a Max, although two similar incidents happened in 2019 with an earlier model of the 737 called NG or next generation, which has the same rudder-pedal system.
The manufacturer said the issue was fixed by replacing three parts. The plane has made dozens of passenger-carrying flights since then, according to data from FlightAware.
United said the parts were related to a landing feature that was designed for other airlines, and United has only nine planes with those parts. The airline said it will work with Boeing, the NTSB and the Federal Aviation Administration “on next steps for these aircraft.”
The NTSB said preliminary information from the plane's flight data recorder, one of the so-called black boxes, confirmed the captain's description of the event. United was able to recreate the same problem on the 2-year-old plane during a test flight at the Newark airport three days later, and reported the problem to the NTSB.
Mechanics couldn't find an obvious cause for the malfunction during an inspection, but they replaced parts of the rudder control system, and the plane operated normally during a second test flight, the NTSB said.
United Airlines pilots said pedals that control rudder movement on the plane were stuck as they tried to keep the plane in the center of the runway during the Feb. 6 landing.
The pilots were able to use a small nose-gear steering wheel to veer from the runway to a high-speed turnoff. The rudder pedals began working again as the pilots taxied to the gate with 155 passengers and six crew members on the flight from Nassau, Bahamas, according to a preliminary report by the National Transportation Safety Board.
Boeing said this is the only rudder-response issue reported on a Max, although two similar incidents happened in 2019 with an earlier model of the 737 called NG or next generation, which has the same rudder-pedal system.
The manufacturer said the issue was fixed by replacing three parts. The plane has made dozens of passenger-carrying flights since then, according to data from FlightAware.
United said the parts were related to a landing feature that was designed for other airlines, and United has only nine planes with those parts. The airline said it will work with Boeing, the NTSB and the Federal Aviation Administration “on next steps for these aircraft.”
The NTSB said preliminary information from the plane's flight data recorder, one of the so-called black boxes, confirmed the captain's description of the event. United was able to recreate the same problem on the 2-year-old plane during a test flight at the Newark airport three days later, and reported the problem to the NTSB.
Mechanics couldn't find an obvious cause for the malfunction during an inspection, but they replaced parts of the rudder control system, and the plane operated normally during a second test flight, the NTSB said.
Last edited by T28B; 7th Mar 2024 at 19:07. Reason: Added content from the link
Simon Hradecky has a good report here:
Incident: United B38M at Newark on Feb 6th 2024, stuck rudder pedals on landing (avherald.com)
Incident: United B38M at Newark on Feb 6th 2024, stuck rudder pedals on landing (avherald.com)
Psychophysiological entity
Please don't let this happen on top of an engine failure after V1. "one of three things to go wrong". Is there any hope that this can only happen after weight on wheels?
I would assume it's the rollout guidance servo.
"The NTSB further reported:
Post-incident troubleshooting and inspection of the rudder control system found no obvious malfunctions with the system or any of its components whose failure would have resulted in the restricted movement observed during flight 1539 and the test flight. As a precaution, the aft rudder input torque tube and associated upper and lower bearings and the rudder rollout guidance servo were removed for further examination by the NTSB systems group.
...
On February 28, 2024, the Systems group met at the Collins Aerospace facility in Cedar Rapids, Iowa to examine and test the SVO-730 rollout guidance servo removed from the incident airplane. The testing was conducted to evaluate the effects that temperature “cold soaking” of the servo might have on the torque required to move the servo’s output crank arm. Testing at room temperature found that the torque to rotate the servo’s output crank arm was within design specifications. The unit was then “cold soaked” for 1 hour and the test was repeated. That testing found that the torque to move the servo’s output crank arm was significantly beyond the specified design limits. Because the servo output crank arm is mechanically connected to the rudder input torque tube, the restricted movement of the servo’s output crank arm would prevent the rudder pedals from moving as observed during flight 1539 and the test flight. Further examination of the SVO-730 rollout guidance servo will be conducted as the investigation continues."
I don't know this aircraft or its systems but I assume a rollout guidance servo would only be fitted for customers who purchased Cat IIIb autoland.
"The NTSB further reported:
Post-incident troubleshooting and inspection of the rudder control system found no obvious malfunctions with the system or any of its components whose failure would have resulted in the restricted movement observed during flight 1539 and the test flight. As a precaution, the aft rudder input torque tube and associated upper and lower bearings and the rudder rollout guidance servo were removed for further examination by the NTSB systems group.
...
On February 28, 2024, the Systems group met at the Collins Aerospace facility in Cedar Rapids, Iowa to examine and test the SVO-730 rollout guidance servo removed from the incident airplane. The testing was conducted to evaluate the effects that temperature “cold soaking” of the servo might have on the torque required to move the servo’s output crank arm. Testing at room temperature found that the torque to rotate the servo’s output crank arm was within design specifications. The unit was then “cold soaked” for 1 hour and the test was repeated. That testing found that the torque to move the servo’s output crank arm was significantly beyond the specified design limits. Because the servo output crank arm is mechanically connected to the rudder input torque tube, the restricted movement of the servo’s output crank arm would prevent the rudder pedals from moving as observed during flight 1539 and the test flight. Further examination of the SVO-730 rollout guidance servo will be conducted as the investigation continues."
I don't know this aircraft or its systems but I assume a rollout guidance servo would only be fitted for customers who purchased Cat IIIb autoland.
I believe that there is an optional third axis for the autopilot that would allow Catlll autoland. Otherwise there is the HGS but that relies on manual rollout control.
Cold soaked actuator with the wrong grease used during maintenance ?
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Does the Max have Cat IIIb capability? It's a long time ago, but the NG that I flew certainly didn't.
Even if a customer receives a Cat IIIb capable aircraft many do not maintain them to keep Cat IIIb operational approval. Some operators don't see a cost/benefit advantage. It appears that Boeing allows customers to opt out at purchase rather than buy capability they don't intend to use. What's wrong with that?
Last edited by EXDAC; 8th Mar 2024 at 15:31. Reason: delete reference to proposed retirement of definitions
As an aside, it seems that FAA is retiring the IIIa, IIIb, and IIIc definitions. ref - https://www.federalregister.gov/docu...ic-definitions
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Thanks for the gen. I last flew the NG in 2004 (yes, I'm an aged bugger), so perhaps the Cat IIIb capability came later. We had Cat IIIb from the start on the Fokker 100, and saw the 737 as a bit of a throwback
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Why?
Even if a customer receives a Cat IIIb capable aircraft many do not maintain them to keep Cat IIIb operational approval. Some operators don't see a cost/benefit advantage. It appears that Boeing allows customers to opt out at purchase rather than buy capability they don't intend to use. What's wrong with that?
Even if a customer receives a Cat IIIb capable aircraft many do not maintain them to keep Cat IIIb operational approval. Some operators don't see a cost/benefit advantage. It appears that Boeing allows customers to opt out at purchase rather than buy capability they don't intend to use. What's wrong with that?
Very happy to be corrected as I have been fully assimilated into Airbus at this point so my Boeing knowledge (based on the Classics!) is only kept updated by idle reading.
I am left wondering why the crew used the nosewheel steering to take a high speed turn off when they had directional control issues. Why di d they not just run long in a straight line?
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Aviation Herald is reporting that another United B38M suffered a runway excursion and main gear collapse at Houston today;
Source; https://avherald.com/h?article=515e3618&opt=0
Just a coincidence or is there a common cause?
Source; https://avherald.com/h?article=515e3618&opt=0
Just a coincidence or is there a common cause?