China Eastern 737-800 MU5735 accident March 2022
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ywagd
If you go to the Eaton.com website and search on B737 stabilizer trim upgrade there is a sales type technical description of 6355C trim motor. Not sure what your getting at in the context of this event though.
If you go to the Eaton.com website and search on B737 stabilizer trim upgrade there is a sales type technical description of 6355C trim motor. Not sure what your getting at in the context of this event though.
Video shows where second black box from MU5735 was discovered - CGTN
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But, if we in a few weeks from now learn that this accident started with a runaway nose down trim where the plane initially was kept from diving with elevator, then this could be of significance.
I think other scenarios are more likely, but when we get FDR data we will know more.
/ywagd
For the above to happen you would need a series of events that is hard to imagine. First the trim motor would need to begin a runaway. As soon as that happened the autopilot or pilot flying would counter that with elevator movement activating the trim brake. If the trim brake failed which would be a completely different failure from the initial runaway the pilots would need to not notice the autopilot disconnect warning, nose pitching down, change in G forces, spinning trim wheels. If any off the above was noticed the pilots would simply hit the trim disconnect switches. They would also intuitively trim counter to the runaway. Either action should stop the runaway. They could then continue the flight using manual trim. The trim brake is a robust system we checked on the first flight of the day so it’s tested often.
I made an argument the left roll (there can be no doubt that a left roll was the start of the flight path deviation) could most likely be caused by either an uncommanded rudder movement or an engine malfunction causing the left engine to lose thrust and taking the crew by surprice. ie crew not taking action before AP disconnect in an out of trim state. Alternatively an uncontained engine failure also damaging rudder cables/controls and/or wing surfaces.
I was not thinking ”rudder hardover” as necessarily not controllable failure.
A uncommanded rudder movement ( or A/T failure like Sriwijaya) and a A/P disconnection and spatial desorientation.
Sriwijaya 182 seems to have rolled left without noticing it, at least initially. Might be the same this time?
An uncontained engine failure could possibly damage the aircraft and cause something like this, but my guess is that if you get a uncontained engine failure you will wake up and get on your toes quite quickly…
To posters with the view that it can not be a rudder hardover/uncommanded movement or Eng failure: What would cause the aircraft to perform a left roll + second half of a barrel roll?
Any ideas?
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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.
The difference with the MAX is the MCAS problems were detected at the start of the aircraft’s operational service life.
How "endemic" it was would depend on whether Boeing cleaned up its act when people started blowing whistles.
If so, it would still be worth following the fate of that batch of aircraft.
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.
Most laughable paragraph I have read in awhile. Get out of the house and stop reading spy novels. No country has DNA samples of its entire population. Especially a country so populous as China. There are no “biometric devices “ scanning you on aircraft entry either. There maybe facial recognition in the terminal but that is about it. And even then it isn’t gathering data about you. But scanning you against a database.
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Runaway trim... doesnt it says on the memory items not to reengage the autopilot? Could this be the case when it level off and reengaged the autopilot leading to another freefall?
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But not yet because the Chinese have only just issued visas (surprise surprise). And they still have the quarantine card to play if they wish to be obstructive for a little while longer.
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Most laughable paragraph I have read in awhile. Get out of the house and stop reading spy novels. No country has DNA samples of its entire population. Especially a country so populous as China. There are no “biometric devices “ scanning you on aircraft entry either. There maybe facial recognition in the terminal but that is about it. And even then it isn’t gathering data about you. But scanning you against a database.
Genotyping (even 10s of thousands) of recovered tissue samples on a forensic STR kit is trivially easy. Genotyping 300 samples from relatives is trivially easy. Statistical matching of STR profiles for identification is trivially easy. Whether you have a pre-existing database would have next to no influence on the technical process. As someone else pointed out above, the difficult bit is finding and collecting the tissue samples.
Maybe not the place to have this discussion as it is completely irrelevant to the topic.
Genotyping (even 10s of thousands) of recovered tissue samples on a forensic STR kit is trivially easy. Genotyping 300 samples from relatives is trivially easy. Statistical matching of STR profiles for identification is trivially easy. Whether you have a pre-existing database would have next to no influence on the technical process. As someone else pointed out above, the difficult bit is finding and collecting the tissue samples.
Genotyping (even 10s of thousands) of recovered tissue samples on a forensic STR kit is trivially easy. Genotyping 300 samples from relatives is trivially easy. Statistical matching of STR profiles for identification is trivially easy. Whether you have a pre-existing database would have next to no influence on the technical process. As someone else pointed out above, the difficult bit is finding and collecting the tissue samples.
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Was just updating some notes on China. Found this one in my notes (long time ago, but a fmr sr NTSB lead says 'there are no new accidents'). An event like this was discussed as an option by some posters.
Case is 24th of November 1992, all fatal accident, 737-300 China Southern Airlines, flight CZ3943, Guangzhou-Guilin, B-2523.
I could not find a final report, but my notes say cause was reported as: "asymmetric thrust, crew failed to recognize roll condition, gave wrong control inputs,.."
Case is 24th of November 1992, all fatal accident, 737-300 China Southern Airlines, flight CZ3943, Guangzhou-Guilin, B-2523.
I could not find a final report, but my notes say cause was reported as: "asymmetric thrust, crew failed to recognize roll condition, gave wrong control inputs,.."
Was just updating some notes on China. Found this one in my notes (long time ago, but a fmr sr NTSB lead says 'there are no new accidents'). An event like this was discussed as an option by some posters.
Case is 24th of November 1992, all fatal accident, 737-300 China Southern Airlines, flight CZ3943, Guangzhou-Guilin, B-2523.
I could not find a final report, but my notes say cause was reported as: "asymmetric thrust, crew failed to recognize roll condition, gave wrong control inputs,.."
Case is 24th of November 1992, all fatal accident, 737-300 China Southern Airlines, flight CZ3943, Guangzhou-Guilin, B-2523.
I could not find a final report, but my notes say cause was reported as: "asymmetric thrust, crew failed to recognize roll condition, gave wrong control inputs,.."
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I can't put my finger on the official Final Report either, but there's a decent Wiki ( https://en.wikipedia.org/wiki/China_...es_Flight_3943 ) and a useful ASN Summary ( https://aviation-safety.net/database...?id=19921124-0 ).
Was just updating some notes on China. Found this one in my notes (long time ago, but a fmr sr NTSB lead says 'there are no new accidents'). An event like this was discussed as an option by some posters.
Case is 24th of November 1992, all fatal accident, 737-300 China Southern Airlines, flight CZ3943, Guangzhou-Guilin, B-2523.
I could not find a final report, but my notes say cause was reported as: "asymmetric thrust, crew failed to recognize roll condition, gave wrong control inputs,.."
Case is 24th of November 1992, all fatal accident, 737-300 China Southern Airlines, flight CZ3943, Guangzhou-Guilin, B-2523.
I could not find a final report, but my notes say cause was reported as: "asymmetric thrust, crew failed to recognize roll condition, gave wrong control inputs,.."
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The Captain had 6k hours.
The first First Officer had 32k hours.
The 2nd First Officer had ~500 hours.
The reason for this seemingly odd crew composition was also clearly stated in the Chinese language reporting:
The 32k-hour pilot was one of the most experienced civil aviation pilot in China. He was one of the first Chinese pilots who started flight training as a civilian, rather than military. He started his career just as the Chinese civil aviation was taking off in the early 80s. He was scheduled to retire this year. The reason he had so many hours but yet was not flying as Captain was the airline had retired the 767 on which he was rated as Captain, so he was now being converted to 737.
The young 2nd First Officer was in the third seat. He was assigned to this flight in order to "gain experience." That's all the Chinese language reporting said about this pilot. No further explanation was given how sitting in the third seat could help gain experience.
The Captain was hired as a 737 captain in January, 2018. Nothing remarkable was reported about him.