Author Topic: Ethiopian Max8 crash  (Read 7713 times)

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Offline M-Sauce

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Re: Ethiopian Max8 crash
« Reply #150 on: April 12, 2019, 04:54:05 AM »
I’m not sure you understand how trim works. You trim for an airspeed. When you reach that airspeed, the aircraft is in trim. In this case, if the jackscrew was at the limit of nose down travel, then that airspeed might have been outside the achievable limit. The trim system, especially in a long aircraft, has to account for all ranges of the CG envelope. But the aerodynamic principles still apply. The faster they went, the closer they got to their stabilised condition and the more effective the elevator input was. And as you pointed out, keeping thrust in increases the pitch up moment from the underslung engines.

Unfortunately, like you mentioned, being at low altitude left them without the room needed to recover. Hell, I don’t even know if the condition was recoverable. As I mentioned earlier, it seems as if this failure scenario is extremely critical on time and correct diagnosis. It could very well be that if corrective actions are slow or if diagnosis of the problem wrong, the aircraft gets itself into an unrecoverable condition. The stabiliser is much larger than the elevator after all.

My former airline had a similar event that almost grounded the EMB145 series in the US. There are similarities in that they found themselves in an aircraft out of trim and without any control of the stabiliser. Quite chilling to watch, came very close to lawn-darting into the Chicago suburbs. See the link below for more info. That website contains a link to download the radar tapes.

https://www.rapp.org/archives/2006/03/eagle_230/

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Offline benclark

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Re: Ethiopian Max8 crash
« Reply #151 on: April 14, 2019, 01:48:02 AM »
I’m not sure you understand how trim works. You trim for an airspeed. When you reach that airspeed, the aircraft is in trim. In this case, if the jackscrew was at the limit of nose down travel, then that airspeed might have been outside the achievable limit. The trim system, especially in a long aircraft, has to account for all ranges of the CG envelope. But the aerodynamic principles still apply. The faster they went, the closer they got to their stabilised condition and the more effective the elevator input was. And as you pointed out, keeping thrust in increases the pitch up moment from the underslung engines.

Unfortunately, like you mentioned, being at low altitude left them without the room needed to recover. Hell, I don’t even know if the condition was recoverable. As I mentioned earlier, it seems as if this failure scenario is extremely critical on time and correct diagnosis. It could very well be that if corrective actions are slow or if diagnosis of the problem wrong, the aircraft gets itself into an unrecoverable condition. The stabiliser is much larger than the elevator after all.

My former airline had a similar event that almost grounded the EMB145 series in the US. There are similarities in that they found themselves in an aircraft out of trim and without any control of the stabiliser. Quite chilling to watch, came very close to lawn-darting into the Chicago suburbs. See the link below for more info. That website contains a link to download the radar tapes.

https://www.rapp.org/archives/2006/03/eagle_230/

 ::cheers::
And this is why having seen some of the replies on this thread in particular I swear we need a sticky with a list of actual airline pilots like yourself Mariano! ::cheers::

Offline johanfrc

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Re: Ethiopian Max8 crash
« Reply #152 on: April 15, 2019, 07:46:00 AM »
AAL have deceided not to fly the MAX planes until at least mid-August:
https://www.theguardian.com/world/2019/apr/14/american-airlines-cancels-boeing-737-max-flights-mid-august
Regards

Johan Clausen

Offline Swag

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Re: Ethiopian Max8 crash
« Reply #153 on: April 19, 2019, 06:18:24 AM »

Offline jhaley101

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Re: Ethiopian Max8 crash
« Reply #154 on: April 19, 2019, 07:50:41 AM »
Great read, really enjoyed the article, thanks for sharing

JH

Offline benclark

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Re: Ethiopian Max8 crash
« Reply #155 on: April 19, 2019, 01:26:17 PM »
Very good read, similar but in far more depth to the video I shared on my FB profile yesterday. The 737 MAX was Boeings attempt to keep up and compete with the A320neo, the latter was able to be upgraded, it's 20 year older competitor shouldn't have been. Economics, and business went over safety, common sense and good engineering.

Side note, not a funny situation at all, but I did laugh a little at this
Quote
“Raise the nose, HAL.” “I’m sorry, Dave, I’m afraid I can’t do that.”
it's sad but the aircraft manufacturer who used to be oh so critical of Airbus and it's fancy computers and how things should have backups is suddenly the one with the issue.

Offline usaflightmaster

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Re: Ethiopian Max8 crash
« Reply #156 on: April 19, 2019, 03:53:35 PM »
I agree, that is a great read.  Thanks a bunch for your bringing that information to our attention.

Derrick

Offline jhaley101

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Offline Toohigh

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Re: Ethiopian Max8 crash
« Reply #158 on: June 05, 2019, 01:45:37 PM »
AZAL Azerbaijan Airlines canceled the order for 10x 737-8max.

Offline Swag

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Re: Ethiopian Max8 crash
« Reply #159 on: June 24, 2019, 06:33:08 AM »
Another excellent article on the subject:

https://www.seattletimes.com/seattle-news/times-watchdog/the-inside-story-of-mcas-how-boeings-737-max-system-gained-power-and-lost-safeguards

Boeing seems to have a very serious corporate culture problem and their management seems to be in complete denial still. If that is true then then MCAS fiasco is just a symptom of that and other accidents caused by cost cutting are likely to follow.
« Last Edit: June 24, 2019, 06:46:13 AM by Swag »