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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)

A0283 28th Mar 2022 14:05


Originally Posted by Dave Gittins (Post 11206847)
Looking at posts 250 and 255 and wholly speculatively, how could a reduction in thrust at top of descent instead have activated a thrust reverser ? Did somebody say they have only found one engine ? Post 214 and nobody has rushed it to say it's wrong.

Dave it means that on the photo and video material that I have seen, there was only one engine visible (suprisingly - with the fan side up) next to a pool of water that they called the 'first pond', the circumference appeared quite intact, but the engine somewhat flattened. I did not observe the removal of that engine from the mud. And did not see the other engine. Indeed nobody commented on this then or later. So we dont know if it is the left or right hand engine that was found.

I did observe for example the removal of the outerwing/winglet from the deep mud, and the removal of a top of one big MLG fragment including trunnions. And observed the handling of the FDR 'can' just after it was found. The CVR can was a Honeywell.

The investigation reports things like 24,000 earlier and yesterday 33,777 pieces found in their press conferences, but does not make statements on the four corners or main components that have been found, apart from the CVR and FDR. They appear to have established a pretty thorough process chain for filtering, handling and identifying parts, so that information should be available by now. That they dont make that public may or may not be surprising.

VFR Only Please 28th Mar 2022 19:31


Originally Posted by Magplug (Post 11206618)
(...) On the one hand the Chinese are being uncharacteristically open with their press conferences but may still be guarded in their admissions of the possibility of a mid-air collision with an errant mil-jet. Everything outside of airways in China is mil-controlled. Consequently getting co-ordination for wx avoidance is downright impossible. Equally an errant military jet may have infringed civil airspace resulting in a mid-air (...)

Am guessing at least one non-Chinese party (Boeing) will take part in this investigation.
A collision may be unlikely, but suppose that were the case. The Chinese would be reluctant, putting it mildly, to admit this.
Interesting dynamics in multinational investigation team, a bit like the WHO looking into the lab-leak hypothesis.

DaveReidUK 28th Mar 2022 20:10


Originally Posted by VFR Only Please (Post 11207000)
Am guessing at least one non-Chinese party (Boeing) will take part in this investigation.

No guesswork required. It has already been announced that the NTSB will participate in the investigation, supported by Boeing and CFM.

B2N2 28th Mar 2022 22:50

The future of Boeing is at stake let’s not forget that.
They’ve barely recovered from the Max debacle and a potential fleet wide problem with the -800 series could very well be the end of it.

BuzzBox 28th Mar 2022 23:24

The Chinese government and media outlets are reporting that all 132 victims have been 'identified' through DNA testing, cross-matched with samples taken from their relatives. That seems quite a tall order, given the accident only occurred a week ago and the difficulty of recovering remains from the crash site.

http://english.www.gov.cn/news/topne...3353285ed.html

dr dre 28th Mar 2022 23:30


Originally Posted by B2N2 (Post 11207075)
The future of Boeing is at stake let’s not forget that.
They’ve barely recovered from the Max debacle and a potential fleet wide problem with the -800 series could very well be the end of it.

Given the airframe has been around for 24 years it would be very rare if an endemic problem that causes catastrophic uncontrollable states has been lying dormant and undiscovered that whole time.

The difference with the MAX is the MCAS problems were detected at the start of the aircraft’s operational service life.

B2N2 29th Mar 2022 05:07


Originally Posted by dr dre (Post 11207084)
Given the airframe has been around for 24 years it would be very rare if an endemic problem that causes catastrophic uncontrollable states has been lying dormant and undiscovered that whole time.

The difference with the MAX is the MCAS problems were detected at the start of the aircraft’s operational service life.

Except this airframe wasn’t 24 years old.


Manufacturer Serial Number (MSN) 41474
Line Number 5453
Aircraft Type; Boeing 737-89P(WL)

First Flight 5 Jun 2015
Age 6.8 Years
Production Site Renton (RNT)
Changes in production methods, materials, quality control etc etc etc.
Boeing is certainly not in the clear.
The Max is still not re-certified for Commercial operations in China and they may delay even further.

BoeingDriver99 29th Mar 2022 08:00

If anyone thinks the Max will ever fly in China again they are dreaming.

ywagd 29th Mar 2022 08:36

Something the newer 737 ng have in common with 737 MAX
All 737 MAX and most 737 ng manufactured 2014 or later (I'm not sure about date) are equipped with a new model of the motor and motor driver that is used for electric trim.

There could be a difference in how the newer motor and motor driver is able to restore normal trim after a runaway trim. Compared with older motors.

The new trim motor and driver that came around 2014 is from Eaton and is called Model 6355C. Among what is new is:
– Brushless three phase motor
– Dual current limit (torque) control circuits

I have not been able to find any information about when the current limit/torque limit kicks in. The strong force required to recover from e.g. a runaway trim if the mistrim is compensated for by elevator, have been shown that it can be impossible to fix with the cockpit wheels. Even if both pilots try to, manually. Unless a maneuver like the "roller coaster maneuver" is used.

There is not so much information about Eaton Stabilizer Trim Motor 6355C available, but here is some.

Search for:
Eaton Stabilizer Trim Motor 6355C

I'm not allowed to post links.

/ywagd

EDLB 29th Mar 2022 08:48

That can be everyone's guess. But since the FDR and CVR data are most likely available in a few days, there is no need to speculate. I am sure the reason will come out regardless what face saving by whatever party might be involved. FDR and CVR data can be sent by email so no need for NTSB or Boeing people on site waiting for any Covid clearance.
China has grounded a lot -800 so they have some interest to figure this out.

CRayner 29th Mar 2022 10:41


Originally Posted by BuzzBox (Post 11207082)
The Chinese government and media outlets are reporting that all 132 victims have been 'identified' through DNA testing, cross-matched with samples taken from their relatives. That seems quite a tall order, given the accident only occurred a week ago and the difficulty of recovering remains from the crash site.

All 132 victims of China's plane crash identified

PCR genetic analysis has come down massively in cost and time lately. I find this only mildly surprising.

BuzzBox 29th Mar 2022 12:10


Originally Posted by CRayner (Post 11207288)
PCR genetic analysis has come down massively in cost and time lately. I find this only mildly surprising.

Sure, but given the aircraft was pulverised by the high-speed impact, I'm surprised they've been able to find and identify DNA material from ALL of the occupants in such a short space of time.

ywagd 29th Mar 2022 14:05

My guess is that the hundreds of workers that have been working for days to collect everything, including parts and fragments from the plane, and body parts, soon had collected many thousands of fractions from both the plane and from victims. When 132 different DNA profiles had been found the next step was to identify the individuals. Often through DNA from relatives.

diclemeg 29th Mar 2022 14:26


Originally Posted by CRayner (Post 11207288)
PCR genetic analysis has come down massively in cost and time lately. I find this only mildly surprising.

I read that headline and am in disbelief.... to isolate 132 individual DNA in that wreckage...especially the souls in the back of the plane who probably ended up far down the hole. I can't fathom how they could do this.

flash8 29th Mar 2022 14:27


PCR genetic analysis has come down massively in cost and time lately. I find this only mildly surprising.
Also given the high surveillance in China, probably all were scanned on a/c entry by various biometric devices and they knew everything irrespective of the manifest. Likely have the DNA on record of all the passengers as well. Probably the most intrusive place in the world so not surprising I agree.

Lake1952 29th Mar 2022 14:31


Originally Posted by diclemeg (Post 11207401)
I read that headline and am in disbelief.... to isolate 132 individual DNA in that wreckage...especially the souls in the back of the plane who probably ended up far down the hole. I can't fathom how they could do this.

Not to get too morbidly graphic, but do you think the souls in the front of the plane fared better than the ones in the back?

diclemeg 29th Mar 2022 14:38


Originally Posted by Lake1952 (Post 11207405)
Not to get too morbidly graphic, but do you think the souls in the front of the plane fared better than the ones in the back?

The point was those in back of plane would end up far into hole, and harder to access/isolate their DNA, vs those in the front, as the impact would scatter on the surface, this notion further makes me doubt their claim of identifying 132 distinct DNA.

A0283 29th Mar 2022 14:45


Originally Posted by BuzzBox (Post 11207326)
Sure, but given the aircraft was pulverised by the high-speed impact, I'm surprised they've been able to find and identify DNA material from ALL of the occupants in such a short space of time.

Based on what I have seen the aircraft is fragmented and the fragments are bent and torn with no sign of fire on them (there was a fire in the trees above the crash site, so apparently some fuel has been thrown forward and up).The largest pieces are parts (top and or bottom panel fragments) of the wing(s) which are a few meters long and say half to one meter wide. One of the engines (bare engine only, no cowlings) was easily identifiable, the other may have been found too as there are two stacks of engine components. Another parts seems to be a part of the THS and another part of the wing. Both are a few meters long, but can be carried by say 6-7 guys. Until now I have only seen one piece of wiring of about 20cm long. No instruments shown at all, but reported that manuals from the cockpit had been recovered. Next to that many white bins with fragments.

In one of the early press conferences they mentioned that all the passengers were Chinese nationals. So there was no need to go into the more lengthy process of asking foreigners to come forward. Based on this you might say that there is a difference in identification time between an all nationals flight and a flight with a mix of (inter-)national passengers.
China makes extensive use of facial recognition, a BBC video showed they could find a reporter in Shanghai or similar within 7 minutes, so they might have used that to take a look at images at the airport to confirm who actually entered the aircraft. On the first day they mentioned one more passenger than thereafter.
Many countries have identification processes in place these days to enable quick identification. The area was hot (30C) and very humid (heavy rain for days), so they had to work fast.

During the weekend the investigation and authorities declared all PoB deceased. From that point on they start making more use of heavy machinery and are building and widening roads to support the recovery effort. The continuous rain has made this a big effort.

wrench1 29th Mar 2022 14:56


Originally Posted by diclemeg (Post 11207401)
I can't fathom how they could do this.

FWIW: Given how they used to identify people in this scenario prior to DNA, it would definitely seem plausible with todays DNA/computer technology to ID their remains much quicker and probably with better accuracy. The human body doesn't simply vaporize on impact.

diclemeg 29th Mar 2022 15:13


Originally Posted by wrench1 (Post 11207418)
FWIW: Given how they used to identify people in this scenario prior to DNA, it would definitely seem plausible with todays DNA/computer technology to ID their remains much quicker and probably with better accuracy. The human body doesn't simply vaporize on impact.

No, it doesn't vaporize, but it is organic and burns and is consumed. I simply do not believe they identified all 132, and no less before they found the second black box. Maybe I am wrong, and maybe they had a big group focused on just DNA sampling. I saw the images of the fires and the heavy rains, and such and just don't believe the claim.


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