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Another MAX airplane issue

Posted on 3/26/19 at 5:45 pm
Posted by LSUFanHouston
NOLA
Member since Jul 2009
41600 posts
Posted on 3/26/19 at 5:45 pm
LINK

quote:

A Southwest Airlines Boeing 737 MAX 8 plane made an emergency landing not long after takeoff from Orlando International Airport, the company confirms. One of the plane's engines experienced a performance issue.


Maybe grounded really needs to mean grounded. I know they were letting the airlines move them around as needed. Only two pilots on board, which is bad enough if it crashes, unless it crashes into a school or something.
Posted by 777Tiger
Member since Mar 2011
93541 posts
Posted on 3/26/19 at 5:46 pm to
quote:

One of the plane's engines experienced a performance issue.


so? nothing to do with MCAS
Posted by PuntBamaPunt
Member since Nov 2010
10070 posts
Posted on 3/26/19 at 5:47 pm to
Yeah, engine failure isn’t the main issue on them
Posted by DustyDinkleman
Here
Member since Feb 2012
20344 posts
Posted on 3/26/19 at 5:47 pm to
Sounds more like an isolated incident.
Posted by wasteland
City of peace
Member since Apr 2011
5923 posts
Posted on 3/26/19 at 5:47 pm to
You can get pills for performance issues
Posted by LSUFanHouston
NOLA
Member since Jul 2009
41600 posts
Posted on 3/26/19 at 5:50 pm to
quote:

nothing to do with MCAS


MCAS doesn't override engine inputs like it does other inputs?
Posted by 777Tiger
Member since Mar 2011
93541 posts
Posted on 3/26/19 at 5:51 pm to
quote:

MCAS doesn't override engine inputs like it does other inputs?


no
Posted by Napoleon
Kenna
Member since Dec 2007
74865 posts
Posted on 3/26/19 at 5:53 pm to
quote:

From a captain friend...
Boeing (and many posters) say "Hey, it's just a trim runaway. Do the drill and all is good." But this is not the simple trim runaway that the QRH contemplates. It starts with a stall warning stick shaker shortly after lift off. Close to the ground this will, and should consume both pilots undivided attention. After a number of seconds they realise that the airplane hasn't stalled and they start figuring out that they may have an airspeed and/or AOA problem.

This is a second problem to deal with on top of the first. And they can't shut the &%$#@ stick shaker off once they realise that it may be spurious. The PM will be frantically scanning the panel to try and find some clue what is going on. And this whole time, among the din of the stick shaker, crews concern for the airplanes flight path, and the confusing instrument indications, MCAS has been intermittently dialing in nose down trim. Not steadily, in a calm cockpit at altitude like the QRH contemplates.

But intermittently in the background of chaos, noise, and confusion. At some point, well past when it would have been timely, the task saturated PF realizes that the trim is working against him/her and the stab cutout switches get turned off. (hopefully)But the shitshow isn't over. Because of everything else going on, this took too long and the airplane is way out of trim. The Lion Air crew reportedly had 60 KG of back pressure on the yoke. Close to the ground, and relying on the lifting component of the underslung engines to help keep the nose up, the crew do not dare reduce power. Now the crew needs to manually trim the airplane, but the airplane is way, way off its trim speed. The B737 QRH makes reference to the large forces
that may be required to break free a servo clutch:

"3 If needed:Use force to cause the disconnect clutch to disengage. Approximately 1/2 turn of the stabilizer trim wheel may be needed.Note:A maximum two-pilot effort on the trim wheels will not cause a cable or system failure."Worse, the "Manual Stabilizer Trim" section of the Boeing FCTM talks about the air loads on a grossly out of trim stab requiring a speed change to reduce the force required to manually trim:

"Excessive air loads on the stabilizer may require effort by both pilots to correct mis-trim. In extreme cases it may be necessary to aerodynamically relieve the air loads to allow manual trimming. Accelerate or decelerate towards the in-trim speed while attempting to trim manually."Sweet Jesus how did this thing get certified?

A guy (or petite gal) has a 60 KG+ force on the yoke trying to stop the airplane from impaling itself into the hard ground just a few thousand feet below, and now he/she has to brute force trim the airplane as well, requiring involved coordination with the PM. Still with all the stick shakers, aural warnings, goofy instrument readings, and whatever else is happening to distract the crew and making communication almost impossible. It is not hard to see how quickly it becomes overwhelming.In addition to a fix for the airplane, if they keep the MCAS system (instead of designing a whole new wing or tail for the airplane), they will have to train the pilots who fly it to deal with its failure.

Right now, there is not a single Max pilot in the world who has been trained for this failure because - there isn't a single simulator in the world that can replicate it. But when they do, all those pilots that claimed "it's just a trim runaway" are going to have a very eye opening simulator session."
Posted by TigerstuckinMS
Member since Nov 2005
33687 posts
Posted on 3/26/19 at 5:59 pm to
Sadly, I've had trim run away far too many times.
Posted by 777Tiger
Member since Mar 2011
93541 posts
Posted on 3/26/19 at 6:00 pm to
sounds like malarkey to me but I will say that integrating the new electronic protections with the old stick shaker/stab trim cutout, etc., seems a like a mismatch, I have flown older Boeings with the shaker/cutout, etc., but not the MAX so not educated on it, sounds like the guy is speculating based on his experience in an older gen 737
Posted by JudgeHolden
Gila River
Member since Jan 2008
18566 posts
Posted on 3/26/19 at 6:04 pm to
quote:

Sadly, I've had trim run away far too many times.


Not my proudest LOL. But LOL.
Posted by 777Tiger
Member since Mar 2011
93541 posts
Posted on 3/26/19 at 6:04 pm to
quote:

Sadly, I've had trim run away far too many times.


word
Posted by Napoleon
Kenna
Member since Dec 2007
74865 posts
Posted on 3/26/19 at 6:05 pm to
From what I gather, the new nacelles throw the center of gravity off and Boeing used technology to overcome this. Then didn't train for any scenarios with the new system.

The "thug life gif" on pilot pages of the pilot stopping the stab trim with his foot has been popular on pilot forums.

Though I also read that anther pilot on the second plane that crashed had turned the stab trim master off.

My info source is mostly the 737 tech group on FB
Posted by BRgetthenet
Member since Oct 2011
118270 posts
Posted on 3/26/19 at 6:05 pm to
I’ve had enough hours to solo, so I understand that. It’s a nightmare to imagine that scenario and think that they went through it. It reminds me of old hag, or sleep paralysis reading that.
Posted by 777Tiger
Member since Mar 2011
93541 posts
Posted on 3/26/19 at 6:10 pm to
quote:

The "thug life gif" on pilot pages of the pilot stopping the stab trim with his foot has been popular on pilot forums.


believe it or not, the procedure used to be to use the stab trim cutout switches to stop the runaway, or grab it with your hand to stop it(which is supposed to activate cutout,) and there are a couple of handles folded into the trim wheel to trim the jet after that, that thing will break a bone if it trims with the handle out, or break your hand if you don't grab it right
Posted by Napoleon
Kenna
Member since Dec 2007
74865 posts
Posted on 3/26/19 at 6:10 pm to
quote:

Hi everybody, I am still getting the impression that there is still some misunderstanding why MCAS was installed and what it does. I have expanded the explanation on my MCAS page (www.b737.org.uk/mcas.htm) as follows:

MCAS is a longitudinal stability enhancement. It is not for stall prevention or to make the MAX handle like the NG; it was introduced to counteract the non-linear lift of the LEAP-1B engine nacelles and give a steady increase in stick force as AoA increases. The LEAP engines are both larger and relocated slightly up and forward from the previous NG CFM56-7 engines to accommodate their larger fan diameter. This new location and size of the nacelle cause the vortex flow off the nacelle body to produce lift at high AoA; as the nacelle is ahead of the CofG this lift causes a slight pitch-up effect (ie a reducing stick force) which could lead the pilot to further increase the back pressure on the yoke and send the aircraft closer towards the stall. This non-linear/reducing stick force is not allowable under FAR §25.173 "Static longitudinal stability". MCAS was therefore introduced to give an automatic nose down stabilizer input during steep turns with elevated load factors (high AoA) and during flaps up flight at airspeeds approaching stall.

To summarise; MCAS will trim the Stabilizer down for 10 seconds (2.5 deg nose down) and pause for 5 seconds and repeat if the conditions (high angle of attack, flaps up and autopilot disengaged) continue to be met. Using electric pitch trim will only pause MCAS for 5s; to deactivate it you need to switch off the STAB TRIM.







Also MCAS is connected to stab trim.



Posted by Napoleon
Kenna
Member since Dec 2007
74865 posts
Posted on 3/26/19 at 6:15 pm to
This is the video of the first officer stopping the runway stab.

Facebook video, sorry
Posted by 777Tiger
Member since Mar 2011
93541 posts
Posted on 3/26/19 at 6:17 pm to
quote:

This is the video of the first officer stopping the runway stab.


pic of the girly hands on the stab trim cutout is not how you would disconnect MCAS btw
Posted by Isabelle81
NEW ORLEANS, LA
Member since Sep 2015
2718 posts
Posted on 3/26/19 at 6:52 pm to
Agree, grounded is grounded. What if one of those planes went down in a populated area?
Posted by LSUFanHouston
NOLA
Member since Jul 2009
41600 posts
Posted on 3/26/19 at 10:58 pm to
I don't understand why, if the plane is different to fly because of location of engines etc, they didn't just, you know, teach the pilots about it and how to adjust their flying accordingly.
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