Airline Pilot Forums

Airline Pilot Forums was designed to be a community where working airline pilots can share ideas and information about the aviation field. In the forum you will find information about major and regional airline carriers, career training, interview and job seeker help, finance, and living the airline pilot lifestyle.




View Full Version : Stick pusher on the 737 Max?


Singlecoil
11-09-2018, 07:31 AM
So some of the news reports about the Lion Air crash are implying that the Max has some sort of stick pusher system that differs from the NG's standard speed trim system. Is that true? Any Max drivers out there care to chime in?


Adlerdriver
11-09-2018, 08:25 AM
Consider the source. They are the same news reports containing statements like this:


"......from the so-called angle of attack sensor. That sensor is intended to maintain air flow over a plane’s wings........."

Gone Flying
11-09-2018, 12:00 PM
I saw something that implied that if the AOA senses that the AC is close to a stall it will run the pitch trim down for 10 seconds, if after 5 seconds of not running it is not satisfied the computer will run the pitch trim down for 10 more seconds. (this is a new feature on the MAX) If the AOA vein sent an erroneous signal to the computer, it may have started running the trim. If the crew didn't disconnect the Stab Trim or something went wrong and it did not disconnect, I think it would have become unrecoverable very quick.

Disclaimer: I have never flown a 737, just saw a video that surfaced talking about the incident. If any 737/max folks want to chime in I'm curious if this is the case.


ZapBrannigan
11-09-2018, 12:16 PM
https://uploads.tapatalk-cdn.com/20181109/4ef701cdb46fb8302e8ed2bcb5d85e6f.jpg


Sent from my iPhone using Tapatalk

1wife2airlines
11-09-2018, 04:46 PM
https://uploads.tapatalk-cdn.com/20181109/4ef701cdb46fb8302e8ed2bcb5d85e6f.jpg


Sent from my iPhone using Tapatalk

Does the 737 NG or earlier models have a stab trim brake like the 727?

Singlecoil
11-13-2018, 02:55 AM
So there is a stick pusher on the Max and apparently few pilots know about it.
https://www.seattletimes.com/business/boeing-aerospace/u-s-pilots-flying-737-max-werent-told-about-new-automatic-systems-change-linked-to-lion-air-crash/

FollowMe
11-13-2018, 03:45 AM
So there is a stick pusher on the Max and apparently few pilots know about it.
https://www.seattletimes.com/business/boeing-aerospace/u-s-pilots-flying-737-max-werent-told-about-new-automatic-systems-change-linked-to-lion-air-crash/

Nowhere in that article does it state that there is a stick pusher. I gather that the system compensates using stab trim, but since Boeing never disclosed how the system operates to the carriers I suppose we are waiting on Boeing to actually confirm said operation.

A Squared
11-13-2018, 03:45 AM
So there is a stick pusher on the Max and apparently few pilots know about it.
https://www.seattletimes.com/business/boeing-aerospace/u-s-pilots-flying-737-max-werent-told-about-new-automatic-systems-change-linked-to-lion-air-crash/


Not a 737 pilot, and my understanding of this comes from things I've read in the media and on various aviation forums, so take it for what it's worth. As I understand it, it's not a "stick pusher" in the sense that it activates, or pushes the stick, ie: adds nose down elevator input. Rather it may react to a high AoA by trimming the horizontal stabilizer for a nose down pitch. Similar effect, different mechanism. I'm out of free articles for the Seattle Times, co I cant comment on the specifics of that article.

rickair7777
11-13-2018, 05:26 AM
So there is a stick pusher on the Max and apparently few pilots know about it.
https://www.seattletimes.com/business/boeing-aerospace/u-s-pilots-flying-737-max-werent-told-about-new-automatic-systems-change-linked-to-lion-air-crash/

WTF????????

intrepidcv11
11-13-2018, 06:42 AM
Quoted from today’s WSJ article on MAX, “One high ranking Being Official said the company had decided against disclosing more details to cockpit crews due to concerns about inundating average pilots with too much information- and significantly more technical data- than they needed or could digest.”

That is absolutely unreal. Anybody want to drop the “if it ain’t Boeing I ain’t going line” on us...

Singlecoil
11-13-2018, 08:45 AM
Nowhere in that article does it state that there is a stick pusher. I gather that the system compensates using stab trim, but since Boeing never disclosed how the system operates to the carriers I suppose we are waiting on Boeing to actually confirm said operation.

That's true, I shouldn't be using the term "stick pusher" as we don't know what it does at this point. The NG's STS system just uses the autopilot to move the stab trim at a slower rate than the switches on the yoke. Is the new system just some variant of that? Does it move the trim wheel more quickly? Can it be disabled using the stabilizer trim cutout switches?

A Squared
11-13-2018, 09:09 AM
That's true, I shouldn't be using the term "stick pusher" as we don't know what it does at this point.


THe AD says that it trims the stabilizer.



Is the new system just some variant of that?



From the descriptions, it's acting in a similar way.



Does it move the trim wheel more quickly?



It moves it at 0.27 degrees per second. I have no idea how that compares to the other things that move the stabilizer.





Can it be disabled using the stabilizer trim cutout switches?



Boeing says you should move the switched to "cutout", but then goes on to say that you might still have to hold the trim wheel to get it to stop.

Dougdrvr
11-13-2018, 07:08 PM
Boeing says you should move the switched to "cutout", but then goes on to say that you might still have to hold the trim wheel to get it to stop.

So it's back to jamming the Capt's knee against the trim wheel, like in the 727?



Search Engine Optimization by vBSEO 3.6.1