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-   -   China Eastern 737-800 MU5735 accident March 2022 (https://www.pprune.org/rumours-news/645805-china-eastern-737-800-mu5735-accident-march-2022-a.html)

Australopithecus 21st Mar 2022 15:45

Absolutely not suggesting it to be the case, but the lower wing skin in that condition makes me wonder about the recent pickle fork AD.

vilas 21st Mar 2022 15:48

Not only it is very possible to put a 737 in such a dive, it's also impossible to pull it out from a high speed dive. It's not a protected aircraft. It was put in 65° dive in Rostov on don, in JAL incident it rolled on the back due to inadvertent rudder trim before it was pulled out. If it was mishandled then it could have easily entered into inverted dive. No surprises there.

ETOPS 21st Mar 2022 15:49

My guess - stab trim runaway not noticed by crew. Autopilot eventually gives up an disengages leading to violent pitch down. Crew figure out what’s wrong and retrim only to overstress during the pullout.

Compton3fox 21st Mar 2022 15:55


Originally Posted by Flocks (Post 11203181)
​​​​​
If it is not in China it doesn't count ? ...

Flash airline flight 604, malfunction lead to autopilot disconnected and pilot not controling their aircraft, that it is low altitude doesn't change anything, high altitude make it even more easier to loose control.

Adam air flight 574 ... High altitude lost of control after autopilot disconnectedhttps://en.m.wikipedia.org/wiki/Flash_Airlines_Flight_604

The descent rate varied during the fatal dive, with a maximum recorded value of 53,760 feet per minute,
From memory, I believe that the descent profile of the Adam air is quit similar of the one seems to be seen here.

I also remember a pilot suicide, with the pilot banking the plane high altitude and also same very fast descent from high FL to ground in few minutes, forgot which plane thought. Not saying it what happened there, but descent profile would also fit.

Would that be Silkair 185 you are referring to? https://en.wikipedia.org/wiki/SilkAir_Flight_185 I recall the tail section separating from the rest of the A/C during the resulting near vertical dive.

Magplug 21st Mar 2022 16:01

As a lifelong professional jet pilot I make a couple of observations.

- A runaway trim that is not detected(?) will put the aircraft into an uncontrollable dive - but NOT a vertical one.
- This a/c seems to have been just fine and stable right up to the point it left cruise altitude approaching destination
- The fact we are seeing lots of panels on the surface with pulled rivets suggests design forces were exceeded in flight leading to structure break up. The rest of the structure is in a very deep hole.
- No conclusions can be drawn from the FR24 data that a recovery was being attempted. This aircraft had departed controlled flight suddenly and catastrophically

For me the circumstances are very similar to Metrojet 9268 (EI-ETJ) that crashed in Sinai. When the four corners are established we may well find that the empennage is not located with the main body of the wreckage indicating separation. The list of causal factors for that separation at the end of a stable cruise is a very short list indeed.

Propellerhead 21st Mar 2022 16:17

Runaway trim is pretty obvious in a 737 as the trim wheel makes a loud clattering noise as it turns. A prolonged turning of the wheel is not something you’d expect in the cruise. And you can stop it by putting your hand on the wheel.

Cool banana 21st Mar 2022 16:28

China Eastern 737-800 MU5735 accident
 
China Eastern pilots’ policy is both crews must be seated 20 mins prior to TOD. This was well past that point.



This is an 6 year old aircraft, but from the data available it looks like a catastrophic failure or a midair collision with a military aircraft/drone.

Any Thunderstorm activity or CAT located close to the TOD? haven't seen any Mid / High Level Significant Weather Chart for that area.

Matt48 21st Mar 2022 16:38

The video appears to show the aircraft either side on with no vertical stab, or a fuselage stripped of all flight surfaces.
Either way, RIP to all souls onboard.
Very sad outcome for all concerned.

Salina Chan 21st Mar 2022 16:44


Originally Posted by Cool banana (Post 11203371)
China Eastern pilots’ policy is both crews must be seated 20 mins prior to TOD. This was well past that point.



This is an 6 year old aircraft, but from the data available it looks like a catastrophic failure or a midair collision with a military aircraft/drone

the thought occurred to me as well, something akin to the GOL mid-air - although the GOL 73 broke up at some point on the way down iirc.

procede 21st Mar 2022 17:11


Originally Posted by lelebebbel (Post 11203385)
Speed is groundspeed, if the aircraft is not travelling horizontally it is going to be erratic

I would think it is (true) airspeed, as transmitted by the transponder. If this was groundspeed, it would not correspond with a dive.

threemiles 21st Mar 2022 17:24


I would think it is (true) airspeed, as transmitted by the transponder. If this was groundspeed, it would not correspond with a dive.
It is Ground Speed indeed. It comes in a packet called Velocity from which Ground Speed and True Track can be derived.
No further speculations on the values, could be a number of reasons.

fdr 21st Mar 2022 17:33


Originally Posted by eagle21 (Post 11203165)
Is this part of the rudder (a/c right)? When comparing the paint scheme it seems like it is the only place that it could come from. Is so it has been found away from the fire
https://cimg4.ibsrv.net/gimg/pprune....f4cef162f.jpeg

Last bits that looked like that I examined had a flutter-type event from going deep into the buffet boundary. Shredding laminate is not a very common failure mode.

Sad day.

There had been some convective weather around that area.

Havingwings4ever 21st Mar 2022 17:37

Ran video(of showing an object coming down in a vertical arc trajectory) by a friend who put it through a forensic video editing program, he does this for a living.

I am pretty confident seeing the resulting video that the tail section is not present during the length of that video. Wing and engine on 1 side seems present but not sure, other side not visible.

Analysis of FR24 data indicates in last 2 minutes an abrupt extreme vertical descent followed by a steep vertical ascent, followed by a final extreme vertical descent till impact. Continuous loss of altitude with a temporary 'leveloff' after the 'climb', followed by increasing extreme rate of altitude loss.
I am not familiar with the airspeed data from FR24.
Pictures are showing popped rivets in several parts of the fuselage indicating over exceedance of design limits.

Somehow crew lost control of the vertical flightpath; likely loss of tail section, immediate or during the last 2 minutes of flight.
failure of rear bulkhead, collision in the air, runaway trim,we are just guessing right now.

Crew seems to have been fighting to get the aircraft recover from the initial steep abrupt vertical descent. Must have been horrific those last 2 minutes.

May their souls be at peace.

30 year plus airline/instructor Boeing/MD's/Airbus, lot of hand flying


A320 Glider 21st Mar 2022 18:04


Originally Posted by jamei (Post 11203395)
exact point they would have been expected to commence descent.

The FO suggests the captain use the washroom before TOD. Captain obliges. Tries to return.

RIP to the crew and pax. Terrible tragedy whatever the explanation is.

awqward 21st Mar 2022 18:08


Originally Posted by threemiles (Post 11203398)
It is Ground Speed indeed. It comes in a packet called Velocity from which Ground Speed and True Track can be derived.
No further speculations on the values, could be a number of reasons.

I think it depends on whether the FR24 data is derived from ADS-B or Multi-Lateration (MLAT)… GS is calculated simply by time between horizontal fixes…

https://www.flightradar24.com/blog/h...hts-with-mlat/

fdr 21st Mar 2022 18:14


Originally Posted by sandiego89 (Post 11203387)
For educational sake, the vertical tail surface is called a vertical stabilizer. The rudder is the movable control surface at the aft end of the vertical stabilizer. In the flight 587 case you share the video of the entire vertical stabilizer departed the aircraft due to overstress from improper rudder inputs.

AA587's loss had a number of factors going on, and for an event in Nov 2001, the term "improper" loses a bit of it's crispness as causation.
  • The FO who was PF had experience in aircraft that were able to take aggressive control inputs.
  • The Airbus manner of giving a rudder ration limiting effect does not act to reduce the sensitivity of the input, ti does the exact opposite; instead of the Boeing method of reducing the deflection for a given deflection of pedal input to reduce loads, the bus does the opposite, it reduces the pedal deflection available, to reduce the rudder deflection, and that means for a given aero load, the Airbus sensitivity of the rudder pedals becomes more sensitive.
  • The certification of the load sequence of the rudder was not required to be accounted for in the loads analysis or in the TIA.
  • the sequence of alternating deflections coinciding with high yaw angles resulted in very high bending loads, and the rudder deflection added alternating torsion loads, and they went wild.
  • The vertical stabiliser was mounted by a series of pins running longitudinally along the perimeter of the composite stabiliser to fix the primary load paths. The secondary load path was by an internal yoke system.... the load required to shear the attachment lugs results in a lever arm for the structure that exceeds the failure loads for the secondary structure, as the lug/pin failure results in a lever arm acting on the secondary structure.
  • AI and TBC both had guidance for jet upset that had crew pre primed (a Gary Klein sort of concept) to wiggle them pedals.
  • The awareness of the structure sensitivity to alternating torsion-bnnding was not recognised in Part 25 before the accident.

We know a lot more after that event than we did beforehand. Amazingly, we were recording QAR/DFDR data of cyclical rudder imputs after that disaster, with the penny not dropped.

BFM 21st Mar 2022 18:15

Sad. Interesting though; that video seems to show the fuselage going supersonic with characteristic vapour puffs. I thought at first it was disintegration debris, but review does not confirm that.

377 Pete 21st Mar 2022 18:15

Last three minutes of MU-5735

https://cimg2.ibsrv.net/gimg/pprune....36796dcb33.jpg

spiros737 21st Mar 2022 18:24

The sheets parts looks like they have been torn by high aerodynamic pressure. the loss of the rudder may have led the plane to a major descent.

jewitts 21st Mar 2022 18:31


Originally Posted by Havingwings4ever (Post 11203407)
Ran video(of showing an object coming down in a vertical arc trajectory) by a friend who put it through a forensic video editing program, he does this for a living.

I am pretty confident seeing the resulting video that the tail section is not present during the length of that video. Wing and engine on 1 side seems present but not sure, other side not visible.

Analysis of FR24 data indicates in last 2 minutes an abrupt extreme vertical descent followed by a steep vertical ascent, followed by a final extreme vertical descent till impact. Continuous loss of altitude with a temporary 'leveloff' after the 'climb', followed by increasing extreme rate of altitude loss.
I am not familiar with the airspeed data from FR24.
Pictures are showing popped rivets in several parts of the fuselage indicating over exceedance of design limits.

Somehow crew lost control of the vertical flightpath; likely loss of tail section, immediate or during the last 2 minutes of flight.
failure of rear bulkhead, collision in the air, runaway trim,we are just guessing right now.

Crew seems to have been fighting to get the aircraft recover from the initial steep abrupt vertical descent. Must have been horrific those last 2 minutes.

May their souls be at peace.

30 year plus airline/instructor Boeing/MD's/Airbus, lot of hand flying

My first thoughts on seeing the raw video. Some of the debris, not found in the hole, seem to be winglets and other wing or tail parts. Maybe nothing to do with the cause.


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