'stuck' rudder pedal during landing roll out; Boeing 737 MAX 8

[Shehasblueeyes]

Reuters reporting this. Real issue or mundane one? (cannot post URLs)

[MechEngr]

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.

Did they move in response to abnormal foot pressure or refuse to move at all? Had the rudder been effective prior to landing? Will have to wait for the NTSB report.

[MichaelKPIT]

Reuters reporting this. Real issue or mundane one? (cannot post URLs)
Little bit more detail here: https://finance.yahoo.com/news/investigators-confirmed-pilots-account-rudder-180808023.htmlFederal 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.

[Desert Dawg]

Simon Hradecky has a good report here:

Incident: United B38M at Newark on Feb 6th 2024, stuck rudder pedals on landing (avherald.com) (https://avherald.com/h?article=515dab89&opt=0)

[DaveReidUK]

"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."

Does anyone know what that's a reference to ?

[Loose rivets]

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?

[EXDAC]

Does anyone know what that's a reference to ?

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.

[Herod]

Does the Max have Cat IIIb capability? It's a long time ago, but the NG that I flew certainly didn't.

[Australopithecus]

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.

[Uplinker]

Cold soaked actuator with the wrong grease used during maintenance ?

[The Banjo]

And yet again Boeing has allocated 20 accountants to formulate the business case to decide if they should fix the issue or cover it up

[EXDAC]

Does the Max have Cat IIIb capability? It's a long time ago, but the NG that I flew certainly didn't.

https://www.pprune.org/archive/index.php/t-547370.html

[Fursty Ferret]

Does the Max have Cat IIIb capability? It's a long time ago, but the NG that I flew certainly didn't.

The fact these things aren't CAT3B capable out of the box is pretty damning in 2024.

[EXDAC]

The fact these things aren't CAT3B capable out of the box is pretty damning in 2024.

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?

[BFSGrad]

As an aside, it seems that FAA is retiring the IIIa, IIIb, and IIIc definitions. ref - https://www.federalregister.gov/documents/2012/02/16/2012-3692/removal-of-category-iiia-iiib-and-iiic-definitionsYour link is dated 2012. Perhaps an NPRM that was never adopted? Current Cat III approach plates and 7110.65 still list Cat IIIa/b/c.

[EXDAC]

Your link is dated 2012. Perhaps an NPRM that was never adopted? Current Cat III approach plates and 7110.65 still list Cat IIIa/b/c.

Thanks. I didn't notice the date. I'll delete the reference.

[Herod]

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

[Speed_Trim_Fail]

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?

My Boeing days are behind me, but my understanding on the max is that the aircraft is delivered with the servo that enables auto rollout capability disabled, rather than not fitted, where the customer does not request it. This enables the aircraft to be upgraded at a later date if desired.

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.

[Miles Magister]

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?

[Porrohman]

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?

[Sailvi767]

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?

It’s likely they slowed to an appropriate speed for using the tiller steering. No need to stay on the runway if the tiller is working and you are at a appropriate speed.

[tdracer]

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?
It's being reported that the pilot drove it into the grass during very poor visibility conditions. So coincidence.

[olster]

The Max does have cat3B capability. Customer option on the NG that I flew previously. Interesting the HGS with the same operator is not certified for cat3B so is either modes cleared or HGS stowed dependent on crew choice. Beware pprune disinformation. I have no idea what happened in this instance nor whether United have cat3B authorization but would be surprised if they didn’t. I am a current instructor on type.

[1southernman]

Upthread it was mentioned that UAL only had nine planes with the HGS ?...If so I would think that the CAT would be restricted to what's allowed w/o it for commonality purposes across that fleet...B

[Sailvi767]

UAL uses the HUD for cat3b capability.

[GlobalNav]

UAL uses the HUD for cat3b capability.
Is it 1 new thing for HGS to be certified for Cat3b? It always used to be Cat3a, I’m pretty sure because it does not contribute to the the automatic rollout. It could be used to monitor rollout, but does it now provide Cat3b rollout steering guidance?

[Sailvi767]

Is it 1 new thing for HGS to be certified for Cat3b? It always used to be Cat3a, I’m pretty sure because it does not contribute to the the automatic rollout. It could be used to monitor rollout, but does it now provide Cat3b rollout steering guidance?


You are correct. The HUD gives Cat3A
One strange HUD issue at my airline years ago. They required all approaches with the RVR below 4000 to be coupled if available unless the RVR was below 1200 in which case you were required to hand fly. Never made a lot of sense to me.

[Verbal Kint]

UAL doesn’t do Cat 3B on the 737. None of the NG’s have a HUD. A handful of the MAX’s do. It’s not approved for use and is being progressively removed from those aircraft.

[EXDAC]

UAL doesn’t do Cat 3B on the 737. None of the NG’s have a HUD. A handful of the MAX’s do. It’s not approved for use and is being progressively removed from those aircraft.

Is HUD not approved for use by UAL or not approved for use on any MAX? I have been involved with 3 HUD cert programs (not Flight Dynamics now Rockwell Collins) and would like to learn more about this.

[Big Pistons Forever]

UAL doesn’t do Cat 3B on the 737. None of the NG’s have a HUD. A handful of the MAX’s do. It’s not approved for use and is being progressively removed from those aircraft.

Off topic I know, but why would you want to remove a proven aid to flight safety ?

[STBYRUD]

If the pilots aren't trained for it, its definitely not an aid to flight safety, quite the contrary :E

[Verbal Kint]

Why don’t they do CAT 3B? I don’t know - very rarely required on the line, & something else to have to train I guess. They do CAT 3A though.

[1southernman]

If the pilots aren't trained for it, its definitely not an aid to flight safety, quite the contrary :E

True...Everybody on the same page and whatnot...Reminds me of when UAL flew the 37 Original and Classic as a combined fleet...I came along after the split but heard stories about the clusters that occurred before the split :)...B

[Guppy60]

And yet again Boeing has allocated 20 accountants to formulate the business case to decide if they should fix the issue or cover it up

Funny as hell!! AKA true]

[olster]

As I said before I am a current simulator instructor on the NG and Max. I am not authorized to say who I work for. For clarification the customer has the HGS on NG and Max on the LHS and it is sop to use it. Further complication with cat 3. NG authorized for cat3a with HGS. Max authorised for cat3b but no HGS allowed. This may be a regulator driven issue and I am not sure why. The Fail Operational autopilot has Rollout mode and the root cause of the above runway excursions may have something to do with that or not as I am just speculating.

[jetpig32]

Upthread it was mentioned that UAL only had nine planes with the HGS ?...If so I would think that the CAT would be restricted to what's allowed w/o it for commonality purposes across that fleet...B

Likely these 9 planes were "white tails" that were moved to United while China was slow to clear the MAX.