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Indonesian aircraft missing off Jakarta

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Indonesian aircraft missing off Jakarta

Old 22nd Nov 2018, 23:52
  #1541 (permalink)  
 
Join Date: Mar 2014
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Originally Posted by FCeng84 View Post
AGBagb - Activation of the both stab cutout switches should disable all electric control of the stabilizer. One can, however, imagine a failure that involves one or more electrical shorts that yields runaway stabilizer that is not arrested via the cutout switches. For that reason, the checklist has #4 suggesting that as a last effort, physically stopping the trim wheel on the flight deck will freeze the stabilizer. MCAS should be disabled via activation of the cutout switches. Short of a failure with the stabilizer electric motors that is separate from MCAS, activating both cutout switches will stop MCAS from moving the stabilizer.
1) Can the motors stand a high rate multiple operation x minutes duty cycle without damage- lockup
2) If locked due to 1 above, can trim wheel still move stab?
3) Is there enough mechanical advantage via trim wheel to move stab from extreme position- airloads ?

Last edited by CONSO; 23rd Nov 2018 at 01:38.
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Old 23rd Nov 2018, 00:08
  #1542 (permalink)  
 
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Originally Posted by wiedehopf View Post
Y

Also the previous flight completed their sector with the stick shaker being active basically the whole flight.
Which absolutely amazes me that the aircraft would be released for the next (fatal) segment.
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Old 23rd Nov 2018, 01:01
  #1543 (permalink)  
 
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Originally Posted by MickG0105 View Post
Am I reading that correctly? Does that show that after the initial upset they redeployed flap during the climb out? If so, and if an MCAS operating condition is flaps up, there appear to be some nose down trim commands that look like what were presumably MCAS commands where they shouldn't be.
Incredibly, it looks like it. I'm assuming that the blue spikes on the automatic-trim graph lines are due to MCAS. But, before I dare advance more ideas, we need a clarification of the 4 different lines of the manual and automatic trim inputs. Also, why does one AOA differ from the other when they eventually track each other with a constant offset; it can't be a graph offset often seen in NTSB graphs. Can someone clarify this.
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Old 23rd Nov 2018, 02:02
  #1544 (permalink)  
 
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Originally Posted by alph2z View Post
Incredibly, it looks like it. I'm assuming that the blue spikes on the automatic-trim graph lines are due to MCAS. But, before I dare advance more ideas, we need a clarification of the 4 different lines of the manual and automatic trim inputs. Also, why does one AOA differ from the other when they eventually track each other with a constant offset; it can't be a graph offset often seen in NTSB graphs. Can someone clarify this.
if one vane was damaged such that the vane was reading offset from its hub, the readings would be consistent, they would be deflected the same by the airstream, but one would have a bias “x” degrees offset from hub. Or, the indexing pin could be un-mated with its receptacle. Improper install.
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Old 23rd Nov 2018, 03:56
  #1545 (permalink)  
 
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Originally Posted by MickG0105 View Post
Does that show that after the initial upset they redeployed flap during the climb out?
To me it seems that retracting the flaps caused the first huge nose down trim. It could be they didn't recognise it was a trim problem (as MCAS is undocumented) and thought something's wrong with the configuration hence they redeployed the flaps. Trim is relatively stable during the 2nd flaps extension compared to the final stage of the flight, so it seems that worked. If they kept this configuration and landed, they would be ok :-(

I believe Boing is going to be facing the grand jury for this. And they should prepare themselves for a massive, in billions, payout to the families. Rightly so!
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Old 23rd Nov 2018, 04:49
  #1546 (permalink)  
 
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After scanning the KNKT flight data recorder graphs for the accident flight, it appears that the final loss of control coincides with a substantial increase in power.
It may be that they were attempting to raise the nose using the thrust-pitch couple, however they may have unwittingly accelerated into a speed vs trim crossover point where they no longer had sufficient nose up trim to hold the nose up.
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Old 23rd Nov 2018, 05:26
  #1547 (permalink)  
 
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@CONSO,
You should read the FCOM before asking such questions.
The answers to your 3 questions are yes, yes and yes.
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Old 23rd Nov 2018, 05:44
  #1548 (permalink)  
 
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Fit hitting shan --- WSJ

https://www.wsj.com/articles/lion-ai...ash-1542922735

By
Ben Otto,Robert Wall andAndy Pasztor
Updated Nov. 22, 2018 6:22 p.m. ET JAKARTA, Indonesia—Lion Air said Thursday it would press Boeing Co. for more details about a new model 737 plane while Indonesian authorities issued their most definitive statement yet that pilots of Flight 610 were battling automated nose-down commands before last month’s fatal crash.The budget airline’s safety director, Daniel Putut, said he would head to the Boeing facility in the Seattle area, where the plane was built, on Nov. 30 to ask about actions the plane maker was taking to prevent a repeat of the accident. “We need to hear from Boeing,” he said.
The system activated after the flight control system believed the plane’s nose was inclined 20 degrees up from level flight. A system that vibrates the control yoke to alert the pilot about the risk of a potential stall , called a stick shaker, also activated, he said.The pilot countered the nose-down maneuver and stabilized the plane, Mr. Utomo said. The jet continued to climb before the MCAS again pushed the nose down. Information provided to lawmakers suggested repeated nose-down input by the plane’s computers -- with weaker nose-up commands from the cockpit crew -- before the 737 MAX rapidly lost altitude and crashed.
goes on . . .
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Old 23rd Nov 2018, 06:29
  #1549 (permalink)  
 
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Stick shaker left side throughout the previous flight ... out of curiosity is it expected that you proceed to destination? I also wonder what it looked like, the flight before that.

Edited to add: and would that normally be also reported in the tech log? (Earlier in this thread, we saw entries from the tech log and I did not recall having seen stickshaker reported?)

Last edited by pax2908; 23rd Nov 2018 at 07:45.
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Old 23rd Nov 2018, 06:46
  #1550 (permalink)  
 
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Originally Posted by b1lanc View Post
Which absolutely amazes me that the aircraft would be released for the next (fatal) segment.
Yes.
Sitting assessing the sequence of events in the sectors prior it is insightful that the aircraft kept getting pushed back at the next crew.

One posits that Boeing may well now be retaining substantial legal firepower.
This does not bode well for the manufacturer.
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Old 23rd Nov 2018, 06:50
  #1551 (permalink)  
 
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Charts extracted direct from the PDF, probably the best resolution we're going to get (sorry for the size, mods).

Bottom chart is the previous DPS-CGK flight.:



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Old 23rd Nov 2018, 07:24
  #1552 (permalink)  
 
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.

This article in The Guardian shows that there was a statement in the Indonesian Parliament ;

https://www.theguardian.com/world/20...ir-says-report

----------

Does anyone know how the recovery of the bodies is going ?

.
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Old 23rd Nov 2018, 07:56
  #1553 (permalink)  
 
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Originally Posted by phil gollin View Post
.

This article in The Guardian shows that there was a statement in the Indonesian Parliament ;

https://www.theguardian.com/world/20...ir-says-report

----------

Does anyone know how the recovery of the bodies is going ?

.
Well, the Guardian article links to a pay-walled Australian article that purportedly reports on the Indonesian Parliament. And the Guardian journo clearly knows all-but-zip about this or any other aspect of aviation.

At this relatively early stage in the hard-core investigation, it's always a tad expected - and sad - that the assorted parties try and "bat the issue back over the net". The manufacturer will say, look at the airline and its procedures; the airline will say, look at the manufacturer and its procedures. Repeat. Repeat. The "truth" will as sure as eggs is eggs lie in between - almost every single sad event like this requires a lot of holes in the cheese to line up, as we should well know.

IIRC, the recent Indonesian press release (if genuine; whose FDR charts are extensively discussed above) said that the search for bodies had now been completed.
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Old 23rd Nov 2018, 08:17
  #1554 (permalink)  
 
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Does anyone know how the recovery of the bodies is going ?
https://www.channelnewsasia.com/news...ation-10961686

JAKARTA: Indonesia on Friday (Nov 23) wrapped up the grim task of identifying Lion Air jet crash victims from recovered body parts, with a preliminary report on the cause of the accident that killed 189 people due next week.

The Boeing 737 Max jet - one of the world's newest and most advanced commercial planes - plunged into the Java Sea on Oct 29 shortly after taking off from capital Jakarta to Pangkal Pinang city, killing all on board.

Since then, investigators have been doing DNA testing on recovered body parts. As of Friday, 125 people have been identified after testing on human remains that filled some 200 body bags, said Arthur Tampi, head of the national police medical centre.

"We have identified 89 men and 36 women, including two foreigners, namely an Italian and an Indian national" who was the flight's captain, Tampi told reporters in Jakarta.

The identification was being called off because all the recovered remains have been tested, he added.

Budget carrier Lion Air has said it is paying a little over US$100,000 in compensation to the families of each crash victim.

The smashed jet's flight data recorder was recovered but divers are still looking for the cockpit voice recorder.

A formal preliminary report on what might have caused the crash is due Wednesda
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Old 23rd Nov 2018, 10:39
  #1555 (permalink)  
 
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I read above several messages from pilots stating that the B737 can be flown with pitch trim at full nose down electric stop, although it requires considerable muscular force and the help of the other pilot.
I also note the EFS system increases forward control column force to approximately four times normal feel pressure during a stall.
Can I thus assume that the pilot testimonies above only apply to conditions where the EFS system DOES NOT kick in ?
And that the B737 does not provide enough elevator authority when the trim is at full nose down AND the EFS system is active ?
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Old 23rd Nov 2018, 10:40
  #1556 (permalink)  
 
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The FDR was recovered under some layer of sand from the seafloor. The CVR will likely be buried under sand as well. Not easy to pick up signals.
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Old 23rd Nov 2018, 10:57
  #1557 (permalink)  
 
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Indonesia Parliament report might be briefly summarised as reported...
pilot fought to keep the plane in the air after it stalled and was nose-diving to the ground.
the aircraft experienced “the same obstacles” (as) on the previous day’s flight from Denpasar to Jakarta but on that occasion the pilot had managed to keep control of the plane
the pilot attempted to offset the (nosedive) action, fighting to keep it in the air
became “increasingly difficult to control the airplane”
the load on the steering wheel became too heavy for the pilot to manually control, and “then the plane drops”
the aircraft crashed into the sea at a speed of more than 400mph.
the 737 had no engine problems

I read somewhere the loads on the control column can become more than one pilot can overcome.
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Old 23rd Nov 2018, 11:04
  #1558 (permalink)  
 
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Originally Posted by Less Hair View Post
The FDR was recovered under some layer of sand from the seafloor. The CVR will likely be buried under sand as well. Not easy to pick up signals.
Given that digital data recorders are now dirt cheap and very robust, it might be easier to just add a dozen around the airframe. That would obviate the current 'Where's Waldo' like searches for the one essential item buried in the mud.
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Old 23rd Nov 2018, 11:25
  #1559 (permalink)  
 
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Given that digital data recorders are now dirt cheap and very robust, it might be easier to just add a dozen around the airframe.
They may be dirt cheap and robust but they still weigh a fair bit and take up physical space. Where in the airframe would you propose to site them, and how would you mount them? How would you get power and the various mic channels to them? And why would you go to all that cost and long-term weight penalty for a comparatively rare event? If you ask the accident investigators, they will tell you it would be better to have a second FDR than another 11 CVRs.
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Old 23rd Nov 2018, 12:01
  #1560 (permalink)  
 
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Given that digital data recorders are now dirt cheap and very robust, it might be easier to just add a dozen around the airframe.
That's like adding floor lamps in your room to offset any bulbs that may burn out. In the end you would be tripping over all the wires wondering which lamp they go. I shudder to think about the same mess of wires in a plane
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