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Boeing 737 MAX 8 Crashes: Lion Air & Ethiopian Airlines

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Boeing 737 MAX 8 Crashes: Lion Air & Ethiopian Airlines

 
Old 04-05-2019, 03:04 PM
  #161  
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Boeing says to grab the trim wheel and physically hold it to not allow any systems to change it.

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Old 04-05-2019, 03:16 PM
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If the cutout switch was indeed in the "cutout" position, then the only way the trim could be moved would be via the manual trim wheel. The manual electric trim switch would have no effect and the FCC/MCAS would also not be able to move the trim.

It appears that they used the cutout switch shortly after 05:40:30 because the trim didn't move after that (note the MCAS trim input at 05:40:45 that resulted in no change in trim). There's no change in trim after that until 05:43:20 when another MCAS input is made and apparently the trim did move. I'm not sure why the trim moved at that point. It may be that they were trying to use the manual electric trim (note the 2 blips at 05:43:15) and realized that it wouldn't work with the switches in cutout. They may have taken the switches out of cutout then?

Dunno, because shortly after that, there is an MCAS trim input and the trim did move then.

And no, they weren't experiencing 2Gs. Rather, they were experiencing -2Gs (floating in their seats) due to the nose dive at the end...

Last edited by nfnsquared; 04-05-2019 at 03:19 PM.
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Old 04-05-2019, 03:52 PM
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I hope Boeing's stock tanks.
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Old 04-05-2019, 11:00 PM
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Originally Posted by gatrhumpy View Post
I hope Boeing's stock tanks.
Maybe on Monday? Smart of them to make the announcement on a Friday after the market closed. Hoping people would forget or not read about it over the weekend.

https://www.wsj.com/articles/boeing-...on-11554494568

Boeing to Cut 737 MAX Production

April 5, 2019

Boeing Co. will cut production of its 737 MAX by a fifth and appointed a special board committee to examine its development of new planes, as the financial impact from two crashes of its best-selling jetliner deepens.

The aerospace giant said Friday that it will trim monthly output of the MAX by 10 aircraft to 42 by mid-April. The move overrides Boeing’s planned increase to 57 a month by this summer. Analysts had expected that higher production would allow Boeing to make almost 600 deliveries of the 737 this year, 90% of them the MAX model.

Regulators are probing those incidents, and Boeing is proposing a software fix and additional pilot training to address a flight-control problem implicated in both crashes. A return to flight and resumption of deliveries for the 737 MAX is expected to be months rather than weeks away, analysts have said.

“We’re adjusting the 737 production system temporarily to accommodate the pause in MAX deliveries, allowing us to prioritize additional resources to focus on software certification and returning the MAX to flight,” Chief Executive Dennis Muilenburg said in a statement.

Earlier Friday Boeing said it has identified a second software problem that must be resolved as part of an overall fix for its anti-stall system to get 737 MAX airliners flying again.

The latest software issues were discovered in the wake of revisions to the automated stall-prevention feature called MCAS, according to people familiar with the matter. The system has been implicated in the March accident, as well a similar nosedive of another 737 MAX last October. The crashes killed all 346 people on the two flights.

Last week, Boeing presented a proposed fix to MCAS, which stands for maneuvering characteristics augmentation system, to some of its 737 MAX operators. But as a result of the extra engineering work, according to these people, completion of a comprehensive proposal by Boeing to fix MCAS is likely to be delayed until at least late April. Testing and approval by the Federal Aviation Administration could take weeks longer.

Boeing on Friday didn’t update financial guidance ahead of its next quarterly earnings report scheduled for April 24.

The production cut will reduce Boeing’s cash as customers hold back payment for undelivered planes. Boeing’s margins could also suffer as costs are spread over a smaller number of completed aircraft.

The new schedule also widens the output gap between Boeing and rival Airbus SE, which plans to boost production of its A320 planes, the 737 MAX’s competitor, to 60 a month. Boeing’s output cut means it will likely cede its title as the world’s biggest plane maker to its European rival at the end of this year.

The production cut will increase pressure on MAX customers ahead of the busy summer travel season. With more than 370 MAX jets already out of service and others remaining undelivered, airlines have already rejiggered their schedules since regulators world-wide grounded the 737 MAX in the wake of the Ethiopian Airlines crash. Southwest Airlines Co. , the largest MAX operator at 34 aircraft, is due to receive an additional 31 this year and 30 in 2020.

Boeing is also forming a four-member board committee to examine its approach to the MAX fixes as well as other development programs. These include the 777X long-range jet, which is due to have its maiden flight this year ahead of first delivery in 2020, and a proposed new midsize jet that could be launched as soon as next year.

The committee will be headed by retired Adm. Ed Giambastiani Jr., a former vice chairman of the Joint Chiefs of Staff. The other members are former Allstate Corp. CEO Ed Liddy, Duke Energy Corp. CEO Lynn Good and Robert Bradway, CEO of Amgen Inc.
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Old 04-06-2019, 11:32 AM
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Old 04-08-2019, 10:51 AM
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Stabilizer Trim

https://www.satcom.guru/2018/11/stabilizer-trim.html

FWIW, ALOT of 737 stabilizer trim technical information.





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Old 04-08-2019, 11:07 AM
  #167  
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Well, that clears things up...





.





j/k, thanks!
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Old 04-08-2019, 11:16 AM
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Old 04-08-2019, 11:49 AM
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Old 04-08-2019, 03:21 PM
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Originally Posted by stogie1020 View Post
Well, that clears things up... ....

Well, shit, someone should send that to Boeing. Probably would've been useful while designing MCAS.
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Old 04-08-2019, 03:24 PM
  #171  
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One thing I wonder about though .... This little guy, sitting in the back .... does he have to have any special training or qualifications?

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Old 04-08-2019, 06:57 PM
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^^^
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Old 04-09-2019, 10:40 AM
  #173  
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Looking at the ET302 FDR data so I'll play armchair NTSB investigator.

5:38:45 pretty clear something happened to the left AoA sensor (bird strike some have theorized), it goes to the +75o reading for awhile, comes down a little and doesn't return until the a/c is in a dive 5:43:30
The MCAS has three short nose down pitch adjustments then two long nose down (5:40:00 and 5:40:20)
The pilots did a short trim pitch up at 5:40:10 and a long trim pitch up at 5:40:28.
Master trim cutout (not on the graph) after 5:40:37 since the MCAS trim down at 5:40:42 has no effect.
Sometime after the trim was re-enabled, there were two pilot trim up commands that don't appear to show much effect.
But another MCAS at 5:43:20 causes the pitch down to almost the maximum 0 (range of 0 nose down to 10 nose up)
Problem is engine power was at or very near 100% until the rapid decent.
The aero forces on the horizontal stabilizer kept getting greater and as attitude was gained the elevator had less effect as shown at 5:43:30

It was wrong of Boeing to not only not fully inform the pilots about MCAS functionality and operation, but also not include a seperate cutout switch so pilots could have disabled it while still have the electric trim stabilizer control.

Last edited by Legend2TL; 04-09-2019 at 10:44 AM.
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Old 04-09-2019, 05:11 PM
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Originally Posted by gatrhumpy View Post
I hope Boeing's stock tanks.
https://www.wsj.com/articles/boeing-...ch-11554826316

Boeing Didn’t Make Any Commercial 737 Sales in March

April 9, 2019

Boeing Co. didn’t book any commercial orders of its 737 jetliner in March, the first month without a sale of the aerospace giant’s best-selling aircraft in almost seven years.

The company said Tuesday that it delivered 11 of its 737 MAX jets in March, less than half the rate of deliveries in the two previous months as the plane maker, airlines and suppliers contend with a global grounding of the plane after two fatal crashes.

Boeing is developing a software fix to address problems detected in the crashes of an Ethiopian Airlines flight last month and a Lion Air flight last year. The crashes killed all 346 people on the two flights. The software fix will need approval from global regulators, and some analysts predict the plane might not return to flight until at least September.

Chicago-based Boeing said last week that it would cut monthly output of the MAX by 10 planes to 42 this month, effectively shelving its plan to boost production to 57 this summer. That will make it harder for Boeing to reach its goal of delivering about 900 jets this year. Dozens of MAX jets are sitting at its Seattle-area assembly plants.

. . . .

Boeing delivered a total of 54 jets in March, taking the total for the year to 149. The company also booked orders for 44 planes, including three business-jet versions of the 737, but no commercial models.

It was the first month since May 2012 that Boeing failed to book a 737 sale, according to company records. Boeing delivered 24 MAX jets in January and 27 in February.

The company has a backlog of 4,625 MAX orders, as well as 78 sales of older versions of the plane. Analysts still expect the plane to drive Boeing’s profit over the next several years. Boeing is expected to trim a closely watched cash-flow goal when it reports earnings on April 24, reflecting delayed delivery payments from some airlines after the MAX’s grounding.
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Old 04-15-2019, 08:22 AM
  #175  
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The real reason Boeing's new plane crashed twice

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Old 04-20-2019, 07:07 AM
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Boeing 737 Unable to Trim!! Cockpit video (Full flight sim)


Go to ~12:00 to see how difficult it is to manually adjust the trim by hand in the cockpit once there aero load forces on the horizontal stabilizer
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Old 04-30-2019, 08:38 AM
  #177  
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ANALYSIS-Why Airbus isn't pouncing on Boeing's 737 MAX turmoil

https://news.yahoo.com/analysis-why-...090507480.html .

At some point Boeing will have to replace the 737, the Max made sense in light of the situation Boeing and it's customer desires.
But at some point Boeing will have to come up with a modern a/c to replace it. First the 757 replacement aircraft which is rumored but yet to announce.
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Old 05-22-2019, 11:45 AM
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At Boeing, the Flap Over One Tiny Light Indicates Much Larger Flaws

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