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Sun May 12, 2019, 02:38 PM

Boeing altered key switches in 737 Max cockpit

In the middle of Boeing 737 cockpits, sitting between the pilot seats, are two toggle switches that can immediately shut off power to the systems that control the angle of the plane’s horizontal tail.

Those switches are critical in the event a malfunction causes movements that the pilots don’t want. And Boeing sees the toggles as a vital backstop to a new safety system on the 737 MAX — the Maneuvering Characteristics Augmentation System (MCAS) — which is suspected of repeatedly moving the horizontal tails on the Lion Air and Ethiopian Airlines flights that crashed and killed a total of 346 people.

But as Boeing was transitioning from its 737 NG model to the 737 MAX, the company altered the labeling and the purpose of those two switches. The functionality of the switches became more restrictive on the MAX than on previous models, closing out an option that could conceivably have helped the pilots in the Ethiopian Airlines flight regain control.

Boeing declined to detail the specific functionality of the two switches. But after obtaining and reviewing flight manual documents, The Seattle Times found that the left switch on the 737 NG model is capable of deactivating the buttons on the yoke that pilots regularly press with their thumb to control the horizontal stabilizer. The right switch on the 737 NG was labeled “AUTO PILOT” and is capable of deactivating just the automated controls of the stabilizer.

On the newer 737 MAX, according to documents reviewed by The Times, those two switches were changed to perform the same function — flipping either one of them would turn off all electric controls of the stabilizer. That means there is no longer an option to turn off automated functions — such as MCAS — without also turning off the thumb buttons the pilots would normally use to control the stabilizer.

Peter Lemme, a former Boeing flight-controls engineer who has been closely scrutinizing the MAX design and first raised questions about the switches on his blog, said he doesn’t understand why Boeing abandoned the old setup. He said if the company had maintained the switch design from the 737 NG, Boeing could have instructed pilots after the Lion Air crash last year to simply flip the “AUTO PILOT” switch to deactivate MCAS and continue flying with the normal trim buttons on the control wheel. He said that would have saved the Ethiopian Airlines plane and the 157 people on board.

https://www.heraldnet.com/business/boeing-altered-key-switches-in-737-max-cockpit/?utm_source=DAILY+HERALD&utm_campaign=f0c4db68b6-RSS_EMAIL_CAMPAIGN&utm_medium=email&utm_term=0_d81d073bb4-f0c4db68b6-228635337

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Arrow 13 replies Author Time Post
Reply Boeing altered key switches in 737 Max cockpit (Original post)
Yo_Mama_Been_Loggin May 2019 OP
Wellstone ruled May 2019 #1
Yo_Mama_Been_Loggin May 2019 #2
Wellstone ruled May 2019 #3
BBG May 2019 #5
BBG May 2019 #8
Wellstone ruled May 2019 #10
George II May 2019 #11
BBG May 2019 #12
erronis May 2019 #7
luvtheGWN May 2019 #13
MineralMan May 2019 #4
erronis May 2019 #9
dem4decades May 2019 #6

Response to Yo_Mama_Been_Loggin (Original post)

Sun May 12, 2019, 02:44 PM

1. Well,now that

 

Boening's chief Lobbyist is the new Pentagon Chief in waiting,the truth is emerging as to the shady pratice's of certain Corporations. Spread enough money around and walla,you got yourself a Certified Airplane.

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Response to Wellstone ruled (Reply #1)

Sun May 12, 2019, 02:48 PM

2. Actually the word is voila not walla

Pronounced vwolla FWIW

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Response to Yo_Mama_Been_Loggin (Reply #2)

Sun May 12, 2019, 02:54 PM

3. Okie Dokie.

 

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Response to Wellstone ruled (Reply #3)

Sun May 12, 2019, 04:15 PM

5. Actually the phrase is okey dokey

But I like that okie dokie spelling. And Siri doesn’t even suggest an alternative to dokie but she did to dokey or maybe she was calling me a donkey for trying to spell dokey.

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Response to BBG (Reply #5)

Sun May 12, 2019, 04:18 PM

8. Okie Dokie

Yeah, I like that!

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Response to BBG (Reply #8)

Sun May 12, 2019, 04:49 PM

10. Could not resist,

 

Okie Dokie came from a Comic Book or Comic Script from the fifties.. Still the best spelling with the true meaning.

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Response to Wellstone ruled (Reply #10)

Sun May 12, 2019, 05:31 PM

11. Viola, now we know how to spell okay dokay!!

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Response to Wellstone ruled (Reply #10)

Sun May 12, 2019, 05:32 PM

12. Although, Florida Man probably spells it Okeedokee

Nt

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Response to Yo_Mama_Been_Loggin (Reply #2)

Sun May 12, 2019, 04:17 PM

7. Wella, wella - from some of my old stomping grounds in Washington

We called it Walla Walla. It would sound weird to say voila-voila.

Also, don't forget Haydn's famous dueling violas.

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Response to Yo_Mama_Been_Loggin (Reply #2)

Sun May 12, 2019, 05:36 PM

13. Vwa -la (phonetically)

with the accent on the second syllable. It means "there, that's it". Alternatively, the word "voici" -- pronounced "vwa-see" means "here, this is it", a fairly reasonable translation...

(As a Canuck who studied French for several years, I never understood where the word "walla" fit in!)

OTOH, I fully understand okey-dokey, whichever way you spell it!

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Response to Yo_Mama_Been_Loggin (Original post)

Sun May 12, 2019, 02:55 PM

4. The 747 MAX fiasco is going to cost Boeing hugely,

both in money and reputation. Inadequate information for pilots, a lack of training and certification policies for pilots who were already checked out on other 737 models, and other factors are going to lead to massive awards in lawsuits.

Bad job, Boeing!

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Response to MineralMan (Reply #4)

Sun May 12, 2019, 04:28 PM

9. All in the name of profits - charge the airlines for an essential feature

And crashes be damned.

Hope the C-suite and stockholders are proud.

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Response to Yo_Mama_Been_Loggin (Original post)

Sun May 12, 2019, 04:16 PM

6. I never want to fly in a 737MAX, I don't believe it's the software.

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