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WIederling
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sun Mar 31, 2019 8:43 am

fadecfault wrote:
What do you think about these incidents? I've spoken to a few of our flights crews (swa) and all of them believe they would have handled the situation correctly.


Any incidents reports around where crew did exactly that and "survived" to tell the story?
One would expect that, right? If your assertion that only poor uneducated third world buggers would be caught by that trap...

probabilities: if the "selector" is training ( and not the design fault as such ) there must have been some more of these setups around.
Murphy is an optimist
 
Heinkel
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sun Mar 31, 2019 8:56 am

Haven't seen it posted here - yes, I've used the search function - If already known and old news, please delete.

BBC News quotes a WSJ report, that one Ethiopian Airlines pilot has said to the other pilot "pitch up, pitch up!" just before the recording died.

http://www.bbc.com/news/business-47759966

Sounds like parts of the transcript of the CVR are leaking.
 
morrisond
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sun Mar 31, 2019 11:39 am

barney captain wrote:
SheikhDjibouti wrote:
SheikhDjibouti wrote:
Please, PLEASE tell me you are a regular big jet pilot. It doesn't have to be a MAX or even a 737, just any transport category aircraft with jet engines and a swept wing.

I have been asking for such an answer for days now, and all I hear is
1) Large jets are stalled all the time / fairly frequently. Or failing that "most airline pilots have done it at some point".

2) They practice stall training on simulators
My point for days now has been that they practice the approach to a stall, and how to avoid entering the stall.
The fact that in 2013 the FAA invited sim manufacturers to introduce full stall capability to their sims tells us it didn't exist before.

3) Stall are easy; I've done them 100's of times. (sotto voce ...in a Cessna)


I want to hear from a 737 or A320 pilot, not a test pilot, not a CFI, not a senior check pilot, not an ex-military fast jet ace. Just an ordinary 737 or A320 pilot.

Have you ever stalled a 737 or A320 with or without passengers, and is it considered routine procedure?

So, morrisond & osiris30 - have you? You have both fought tooth & nail on this issue as if you have some special insight into this matter. :scratchchin:


barney captain wrote:
Maybe I can help -

You would never practice any stall maneuver in a 737 (testing certification notwithstanding).

You DO practice stalls while working on your ratings in smaller GA aircraft - quite regularly.

Up until last year in the US, we routinely practiced approach to stall maneuvers in the sim.

Starting last year, the FAA mandated advanced maneuvering training that requires us to fully stall the aircraft at both low and high altitudes and practice recovery. Again, in the sim only.

Thank you so much. (assuming that you are qualified to comment....)

(I'm not doubting it one iota, but since I queried those who argued against me, I shouldn't automatically accept you simply because you confirm everything I said :lol: )


No problem.

Current 737 CA, 15,000 hrs on type. ;)


Do you mind sharing with us - how hard is it to unstall the 737 in the SIM? If it happened in real life would it "All bets are off" or would there be a reasonable chance of recovery?

How hard is it to get the 737 stall in the first place?

Thanks
 
Noshow
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sun Mar 31, 2019 12:31 pm

Avweek had a 737 sim ride to experience some newly expanded stall enabled sim software.

https://www.youtube.com/watch?v=zCJco59tqoQ
 
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SomebodyInTLS
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sun Mar 31, 2019 2:13 pm

morrisond wrote:
By stopping the melodramatics I was referring to the "All bets are off" - A full stall is recoverable from and it does not require superhuman piloting skills- it does not mean automatic crash, in fact the odds of crashing with a qualified pilot would b quite low.

The MAX will stall slightly quicker than the NG - but we are talking slightly - it's way out of the normal flight envelope.


Yes, sorry. I apologise - I went a bit ranty (it was late and I was tired) and in fact was trying to edit my reply to soften it when I realised your were talking about "all bets are off" and not the meat of what I had written... but the forum wouldn't let me change it.
"As with most things related to aircraft design, it's all about the trade-offs and much more nuanced than A.net likes to make out."
 
morrisond
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sun Mar 31, 2019 2:43 pm

SomebodyInTLS wrote:
morrisond wrote:
By stopping the melodramatics I was referring to the "All bets are off" - A full stall is recoverable from and it does not require superhuman piloting skills- it does not mean automatic crash, in fact the odds of crashing with a qualified pilot would b quite low.

The MAX will stall slightly quicker than the NG - but we are talking slightly - it's way out of the normal flight envelope.


Yes, sorry. I apologise - I went a bit ranty (it was late and I was tired) and in fact was trying to edit my reply to soften it when I realised your were talking about "all bets are off" and not the meat of what I had written... but the forum wouldn't let me change it.


No worries - there has just been a lot of hyperbole relating to the 737 - the MAX changes (excepting the botched MCAS system which paradoxically was an attempt to make the 737 safer probably as Boeing along with Airbus might have been concerned about declining training standards worldwide) didn't change it that much making the basic airplane unsafe.

That is all I have been defending - the basic soundness of the 737 as a reliable safe system (except for the first implementation of MCAS).
 
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PixelFlight
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sun Mar 31, 2019 2:48 pm

dragon6172 wrote:
SheikhDjibouti wrote:
This pitching up when applying power is partly due to the sheer power of the engines, and partly due to their positioning. Particularly in the MAX.

In fact, aren't we now coming full circle, back to part of the reason for MCAS in the first place - to mitigate against the natural tendency of a 737 MAX to pitch up when applying power as a natural reaction to avoid the early onset of a stall.



MAX engines only have a slight increase in power over NG (about 700 lb thrust more) and are not slung lower than those on the NG. The pitch up tendency that MCAS is installed to prevent comes from the fact that the LARGER NACELLES create lift when the aircraft angle of attack is above a certain amount. Because the nacelles are forward of the CG this lift causes a pitch up moment.

This has been covered at least 100 times between the three main MAX threads.

Exactly. What is less debated is the fact that Boeing could have choose to rise the fuselage with telescopic landing gears to keep the nacelle of the bigger engine in the same place as before. This is finally what Boeing was forced to do for the 737 MAX 10 anyway, but because of the extra fuselage length. The B737 have very low fuselage (for historical reason) compared to the A320.

Image

More details: https://www.quora.com/What-are-the-diff ... Boeing-737
:stirthepot: 737-8 MAX: "For all speeds higher than 220 Kts and trim set at a value of 2.5 units, the difficulity level of turning the manual trim wheel was level A (trim wheel not movable)." :stirthepot:
 
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PixelFlight
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sun Mar 31, 2019 2:51 pm

flybucky wrote:
speedbored wrote:
AoA sensors? Care to give us a link to the incident report?

2 incidents that I know about with 2 faulty AOA sensors outvoting the 3rd valid one:
2008 A320 acceptance flight - crashed into the sea with no survivors.
2014 A321 Lufthansa 1829 - dropped 4000 ft before the pilots disconnected the ADR and recovered the flight.

speedbored wrote:
But nothing to suggest that the freezing was due to any specific property of the type of sensor being used so no reason to believe that having 3 different sensor types on the aircraft would have made any difference.

Exactly. That's why 3 sensors (while better than 2 sensors) is not fail proof. There needs to be an independent backup AOA calculation that does not rely on AOA sensors.

Flight dynamic predictive sensors filter.
:stirthepot: 737-8 MAX: "For all speeds higher than 220 Kts and trim set at a value of 2.5 units, the difficulity level of turning the manual trim wheel was level A (trim wheel not movable)." :stirthepot:
 
Heinkel
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sun Mar 31, 2019 3:00 pm

PixelFlight wrote:
Exactly. What is less debated is the fact that Boeing could have choose to rise the fuselage with telescopic landing gears to keep the nacelle of the bigger engine in the same place as before. This is finally what Boeing was forced to do for the 737 MAX 10 anyway, but because of the extra fuselage length. The B737 have very low fuselage (for historical reason) compared to the A320.


No, that is not the full truth. As mentioned in this thread several times, the 737 MAX 10 "goes on it's tiptoes" just before rotation and extends the working length of the undercarriage rough 10". This is to avoid tailstrike.

During the rest of the time (static, taxiing, begin of the TO-roll) the 737 MAX 10 sits as low to the ground as any other 737. Not sure, if this "rising system" is active on landings, too.
 
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PW100
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sun Mar 31, 2019 3:07 pm

morrisond wrote:
SomebodyInTLS wrote:
morrisond wrote:
By stopping the melodramatics I was referring to the "All bets are off" - A full stall is recoverable from and it does not require superhuman piloting skills- it does not mean automatic crash, in fact the odds of crashing with a qualified pilot would b quite low.

The MAX will stall slightly quicker than the NG - but we are talking slightly - it's way out of the normal flight envelope.


Yes, sorry. I apologise - I went a bit ranty (it was late and I was tired) and in fact was trying to edit my reply to soften it when I realised your were talking about "all bets are off" and not the meat of what I had written... but the forum wouldn't let me change it.


No worries - there has just been a lot of hyperbole relating to the 737 - the MAX changes (excepting the botched MCAS system which paradoxically was an attempt to make the 737 safer probably as Boeing along with Airbus might have been concerned about declining training standards worldwide) didn't change it that much making the basic airplane unsafe.

Was MCAS introduced as "Boeing (along with Airbus) might have been concerned about declining training standards worldwide"?
Or was it required to meet FAR regulations?
Immigration officer: "What's the purpose of your visit to the USA?" Spotter: "Shooting airliners with my Canon!"
 
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PixelFlight
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sun Mar 31, 2019 3:11 pm

Heinkel wrote:
PixelFlight wrote:
Exactly. What is less debated is the fact that Boeing could have choose to rise the fuselage with telescopic landing gears to keep the nacelle of the bigger engine in the same place as before. This is finally what Boeing was forced to do for the 737 MAX 10 anyway, but because of the extra fuselage length. The B737 have very low fuselage (for historical reason) compared to the A320.


No, that is not the full truth. As mentioned in this thread several times, the 737 MAX 10 "goes on it's tiptoes" just before rotation and extends the working length of the undercarriage rough 10". This is to avoid tailstrike.

During the rest of the time (static, taxiing, begin of the TO-roll) the 737 MAX 10 sits as low to the ground as any other 737. Not sure, if this "rising system" is active on landings, too.

Boeing logic... Make everything more complex without synergy.
:stirthepot: 737-8 MAX: "For all speeds higher than 220 Kts and trim set at a value of 2.5 units, the difficulity level of turning the manual trim wheel was level A (trim wheel not movable)." :stirthepot:
 
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Finn350
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sun Mar 31, 2019 5:11 pm

Here is an interesting Youtube video of Alaska Airlines full stall training in an 737-800 simulator
https://www.youtube.com/watch?v=zCJco59tqoQ
 
m66
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sun Mar 31, 2019 5:30 pm

PixelFlight wrote:
osiris30 wrote:
speedbored wrote:
This is exactly why I call the actual sensors redundancy method an industry width issue. Even the 4 sensors of the A350 will travel trought the same environment. If that environment is so harsh to froze one sensor in perfect condition then the others are certainly close to froze very soon. Adding more sensors is effective to disable erratic sensor that fail because there where damaged. Adding sensors is not effective if there will fail due to a common environmental cause. This risky game at the corner of the probability must be addresses more properly. Fortunately the solution exists: sensors filter with flight dynamic predictor. The individual sensor contribution to the flight dynamic predictor is filtered by the accuracy of the result of the previous prediction against all the others observable variables. The flight computers will gets a probability of the value instead of a discrete value with a unknown precision. This allow to compute the safest action given the reduced flight domain due to lost of precision.


Unfortunately, that might bring you in trouble when the plane suddenly is actually in trouble and these actual sensor readings, although bad, might be correct.
 
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PixelFlight
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sun Mar 31, 2019 5:36 pm

m66 wrote:
PixelFlight wrote:
osiris30 wrote:


Unfortunately, that might bring you in trouble when the plane suddenly is actually in trouble and these actual sensor readings, although bad, might be correct.

Fortunately the predictive filtering is precisely designed to select the sensors that predicted the real situation over the sensors that predicted all others situations.
:stirthepot: 737-8 MAX: "For all speeds higher than 220 Kts and trim set at a value of 2.5 units, the difficulity level of turning the manual trim wheel was level A (trim wheel not movable)." :stirthepot:
 
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PixelFlight
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sun Mar 31, 2019 5:43 pm

Finn350 wrote:
Here is an interesting Youtube video of Alaska Airlines full stall training in an 737-800 simulator
https://www.youtube.com/watch?v=zCJco59tqoQ

This prove that civil aircraft flight dynamic models are able to predict aircraft moves even in full stall situation.
Aside of this, while the stick shaker is obviously effective to raise the pilot attention, I found it annoying once the pilot have to focus his workload on the critical actions.
:stirthepot: 737-8 MAX: "For all speeds higher than 220 Kts and trim set at a value of 2.5 units, the difficulity level of turning the manual trim wheel was level A (trim wheel not movable)." :stirthepot:
 
Backseater
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sun Mar 31, 2019 6:54 pm

I am currently focusing on AoA sensor technology and part traceability.
My concern is that many maintenance teams may have handled AoA sensors a bit too casually, because in the past sensors failed mostly at altitude, for instance by having ingested tiny amounts of water that then froze the bearings.
What MCAS has done for 737s is bring AoA issues from "worrisome" to "potentially catastrophic."

How do maintenance crews handle AoA sensor replacement?
A/C comes in with pilot log showing "unreliable airspeed, ..." pointing to a "possible" faulty sensor.
Do 737 MAX operators have a new sensor on their shelf ready to be installed? or just a used spare? I don't know!

I also do not know the list price of a new UTC 0861FL1 but it is probably in the tens of thousands of dollars. In 2013, when mandating a particular type of AoA sensor (not the one used on the MAX!), the FAA wrote "replace the AOA sensor with a new AOA sensor, the cost of which could be up to $37,622."

Last week, I search for Rosemount 0861FL1 around the world, thanks to several on-line traders and spare part sites. Prices are unfortunately rarely shown, I would have to send RFQs to see the actual price. Anyway, I found about 100 sensors of the type used on the MAX (as well as on the 737NG, 757, 767 and 777):
US:75, CAN:3, UK:16, FR:3, Cyprus:2, NL:1, ...
Spares were typically listed as:
- NE (8) new
- NS (2) surplus
- OH (15) overhauled
- SV (54) serviceable
- AR (22) as removed i.e. salvage (at first, I thought it meant "Authorized Release", but apparently not!)
The highest price was $7,500 from a pure trader (no tech work) in Serbia/Bali. Actually, that unit was probably a good one because it seems to have been overhauled/re-certified(?) by "LuftHansa Technik"
Other prices I found were in the $1,500/$3,000 range but I could not really determine what condition they were in.

So, if Boeing does not mandate AoA replacement with a new part (I do not know whether they do or don't), the provisioner of an airline always has multiple choices.
 
dragon6172
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sun Mar 31, 2019 7:59 pm

Backseater wrote:
So, if Boeing does not mandate AoA replacement with a new part (I do not know whether they do or don't), the provisioner of an airline always has multiple choices.

Boeing can mandate all they want (I doubt they do for anything), the operator will decide what kind of part (new, overhauled, as removed, etc) they want to use.

You can remove a known working part from an aircraft, tag it "removed in serviceable condition", and install it on the aircraft parked next on the flightline. It's called cannibalization and it happens all the time. Obviously whatever maintenance procedures have to be followed after install to verify the system is working as it is supposed to
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Backseater
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sun Mar 31, 2019 8:11 pm

dragon6172 wrote:
Backseater wrote:
So, if Boeing does not mandate AoA replacement with a new part (I do not know whether they do or don't), the provisioner of an airline always has multiple choices.

Boeing can mandate all they want (I doubt they do for anything), the operator will decide what kind of part (new, overhauled, as removed, etc) they want to use.

You can remove a known working part from an aircraft, tag it "removed in serviceable condition", and install it on the aircraft parked next on the flightline. It's called cannibalization and it happens all the time. Obviously whatever maintenance procedures have to be followed after install to verify the system is working as it is supposed to

Is your last sentence complete?
 
ELBOB
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sun Mar 31, 2019 8:25 pm

RickNRoll wrote:

Yes. Their position more forward of the CG.


Position of the engines to the CoG is IRRELEVANT in terms of thrust. Otherwise, tail-engined airliners would pitch themselves into the ground...

Just drop the obsession with the Max and thrust. Thrust is not the reason that MCAS exists.
 
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Finn350
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sun Mar 31, 2019 9:01 pm

Noshow wrote:
Avweek had a 737 sim ride to experience some newly expanded stall enabled sim software.

https://www.youtube.com/watch?v=zCJco59tqoQ


Now I noticed you had already posted this one
 
bob75013
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sun Mar 31, 2019 10:26 pm

Backseater wrote:
dragon6172 wrote:
Backseater wrote:
So, if Boeing does not mandate AoA replacement with a new part (I do not know whether they do or don't), the provisioner of an airline always has multiple choices.

Boeing can mandate all they want (I doubt they do for anything), the operator will decide what kind of part (new, overhauled, as removed, etc) they want to use.

You can remove a known working part from an aircraft, tag it "removed in serviceable condition", and install it on the aircraft parked next on the flightline. It's called cannibalization and it happens all the time. Obviously whatever maintenance procedures have to be followed after install to verify the system is working as it is supposed to

Is your last sentence complete?


Yes it is complete, but in poor english (not criticizing the poster) try this end which says the same thing "is working as expected."
 
Backseater
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Apr 01, 2019 1:17 am

bob75013 wrote:
Backseater wrote:
dragon6172 wrote:
Boeing can mandate all they want (I doubt they do for anything), the operator will decide what kind of part (new, overhauled, as removed, etc) they want to use.

You can remove a known working part from an aircraft, tag it "removed in serviceable condition", and install it on the aircraft parked next on the flightline. It's called cannibalization and it happens all the time. Obviously whatever maintenance procedures have to be followed after install to verify the system is working as it is supposed to

Is your last sentence complete?


Yes it is complete, but in poor english (not criticizing the poster) try this end which says the same thing "is working as expected."

I certainly did not intend to criticize "dragon6172" insightful post. Since his sentence ended without a period, and he had just talked about cannibalization of parts, I dreaded that he might have had in mind to end his sentence with a scary ", may or may not be followed.".
 
wjcandee
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Apr 01, 2019 1:19 am

Well, the WSJ finally acknowledged today what I have been saying for weeks: you can't trust the pronouncements of the Ethiopian AIB about this. It is as likely to be total BS as it is likely to be factual:

"American air-safety officials also ... say the Ethiopians have provided often limited access to relevant crash information..." They also say the Ethiopians have been "slow to provide" (meaning "have not yet provided") the CVR and DVDR raw data.

The Ethopians are engaged in if not a cover-up, a media strategy to get ahead of the story that the raw data will tell by leaking characterizations favorable to their position ("It was the plane's fault") where there are lots of reasons to believe that this wasn't an MCAS incident. That they are being coy about it, instead of pointing to actual DVDR data showing it is or isn't, is highly-revealing.
 
planecane
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Apr 01, 2019 2:39 am

wjcandee wrote:
Well, the WSJ finally acknowledged today what I have been saying for weeks: you can't trust the pronouncements of the Ethiopian AIB about this. It is as likely to be total BS as it is likely to be factual:

"American air-safety officials also ... say the Ethiopians have provided often limited access to relevant crash information..." They also say the Ethiopians have been "slow to provide" (meaning "have not yet provided") the CVR and DVDR raw data.

The Ethopians are engaged in if not a cover-up, a media strategy to get ahead of the story that the raw data will tell by leaking characterizations favorable to their position ("It was the plane's fault") where there are lots of reasons to believe that this wasn't an MCAS incident. That they are being coy about it, instead of pointing to actual DVDR data showing it is or isn't, is highly-revealing.


I hope they share the information. It is important to understand what all the contributing factors to this crash were. I struggle to comprehend how a 737 MAX pilot wouldn't recognize an MCAS failure and hit the cutoff switches so soon after lion air.

MCAS needed to be fixed either way but if something else was the primary cause of this crash, it needs to be known so that it can be addressed as well.
 
Backseater
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Apr 01, 2019 3:09 am

In order to elicit any comments and corrections, here is my current understanding of the AoA data path on the 737 MAX:

Image
 
fadecfault
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Apr 01, 2019 3:48 am

Backseater wrote:
In order to elicit any comments and corrections, here is my current understanding of the AoA data path on the 737 MAX:

Image

Incorrect. There are 2 channels on the aoa. One feeds the symd and the other feeds the onside adiru which provides data to the onside fcc.
Stick shaker is only activated by the symd. Mcas is only activated by the active fcc.
The views and opinions written here are my own and do not reflect those of my employer.
 
Backseater
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Apr 01, 2019 4:53 am

fadecfault wrote:
Incorrect. There are 2 channels on the aoa. One feeds the symd and the other feeds the onside adiru which provides data to the onside fcc.
Stick shaker is only activated by the symd. Mcas is only activated by the active fcc.

Thank you for your corrections.
So, the 861FL1 has another analog channel to send sin & cos to the onside ADIRU? or is it sent digitally?
Where is the final AoA value elaborated?
Who puts the final AoA on the ARINC bus (so that the FDR can record it)?
When maintenance plugs an ARINC 429 bus reader to check one of the AoA sensors (I only assume they do because I do not have access to the AMM procedure), do they use a TEST ONLY connector on the onside ADIRU? Do they have another choice?
 
Planetalk
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Apr 01, 2019 5:17 am

wjcandee wrote:
Well, the WSJ finally acknowledged today what I have been saying for weeks: you can't trust the pronouncements of the Ethiopian AIB about this. It is as likely to be total BS as it is likely to be factual:

"American air-safety officials also ... say the Ethiopians have provided often limited access to relevant crash information..." They also say the Ethiopians have been "slow to provide" (meaning "have not yet provided") the CVR and DVDR raw data.

The Ethopians are engaged in if not a cover-up, a media strategy to get ahead of the story that the raw data will tell by leaking characterizations favorable to their position ("It was the plane's fault") where there are lots of reasons to believe that this wasn't an MCAS incident. That they are being coy about it, instead of pointing to actual DVDR data showing it is or isn't, is highly-revealing.


I have no idea how you got from what the article says to your claim in your first paragraph. The WSJ has acknowledged nothing you've said. Clearly you're reading into it what you want to.

Your position has been clear from the start and as such is not based on facts so noone is going to take it seriously. Anyone making grand claims without any evidence loses any credibility unfortunately.

I'd love to know your reasons to believe this wasn't an MCAS incident. Though didn't you earlier say the flaps wouldn't have been up so perhaps you're still way behind the rest of us?

Global regulators have grounded the plane, and have stated there are similarities in the crashed, Boeing is working on a fix for the system it acknowledges the is flawed, and some people are still in complete denial. Humans are such a funny bunch, and the way their emotions completly overrule reasoning when their pride is hurt.

It's also touching that some people seem to think defending a transport manufacturer on an Internet forum is going to have any effect in the real world.
 
WIederling
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Apr 01, 2019 6:54 am

wjcandee wrote:
The Ethopians are engaged in if not a cover-up, a media strategy to get ahead of the story that the raw data will tell by leaking characterizations favorable to their position ("It was the plane's fault") where there are lots of reasons to believe that this wasn't an MCAS incident. That they are being coy about it, instead of pointing to actual DVDR data showing it is or isn't, is highly-revealing.


You could turn this around. There are some accidents and incidents around that were deemed Crew Error by the US side of things that are still seen as contentious by the non US side. ( worthless, I know. Just unprofessional and corrupt Third Worlders )
Murphy is an optimist
 
XRAYretired
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Apr 01, 2019 7:58 am

wjcandee wrote:
Well, the WSJ finally acknowledged today what I have been saying for weeks: you can't trust the pronouncements of the Ethiopian AIB about this. It is as likely to be total BS as it is likely to be factual:

"American air-safety officials also ... say the Ethiopians have provided often limited access to relevant crash information..." They also say the Ethiopians have been "slow to provide" (meaning "have not yet provided") the CVR and DVDR raw data.

The Ethopians are engaged in if not a cover-up, a media strategy to get ahead of the story that the raw data will tell by leaking characterizations favorable to their position ("It was the plane's fault") where there are lots of reasons to believe that this wasn't an MCAS incident. That they are being coy about it, instead of pointing to actual DVDR data showing it is or isn't, is highly-revealing.


I think I would be right in saying that, with the exception of a couple of statements by the EA CEO in the two or three days following the crash, the only leaks have come from un-named US officials to the WSJ (reprehensible?). Perhaps contrary to what you may think, these leaks tend to support MCAS being a signifcant contributor.

I suspect the strained relationship reflects the lack of trust on both sides - no good for anyone. Rest assured, I think it unlikely that the NTSB will sign up to any investigation report it does not support in its entirity.

The rest of it is flim-flam in my view.
 
flybucky
Posts: 376
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Apr 01, 2019 8:08 am

The Preliminary Report is set to be released on Monday (April 1).

A preliminary report into the fatal crash of an Ethiopian Airlines jet last month will be released Monday.

The timing of a media briefing will be announced Monday, said Nebiat Getachew, a spokesman for Ethiopia’s foreign ministry. Boeing has said it is reviewing the report.

https://www.bloomberg.com/news/articles ... sed-monday
 
wjcandee
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Apr 01, 2019 8:23 am

Let's just see how much actual raw data is provided to the BEA, AAIB and/or NTSB in connection with or subsequent to the release of the "preliminary report".

I'm not defending a manufacturer. I'm not saying that I am confident that the Ethiopians are going to lie this time. I am saying that there are really-strong reasons here to demand the release of the raw data to NTSB and others so that an independent agency (like AAIB or BEA if you really think that NTSB is corrupt, which is beyond-stupid) can evaluate it. And that I am disinclined to take anything the Ethiopians say at face value. And again, nothing to do with who or where these folks are located, everything to do with their past actions.

As to whether folks in other countries still have doubts about prior conclusions of the NTSB, I'm not sure which ones our member was referring to (Egypt? That's just risible.). But regardless of whether the NTSB is always right, I choose to believe that they are honest and operate with the highest level of integrity in a transparent process that puts everything on the table for all the "parties" (i.e. entities with a vested interest in the outcome) to see and analyse and dispute if they wish. The overall process is fair and open, which what Ethiopia is doing is plainly not.
 
flybucky
Posts: 376
Joined: Tue Apr 17, 2018 7:44 pm

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Apr 01, 2019 8:52 am

wjcandee wrote:
Let's just see how much actual raw data is provided to the BEA, AAIB and/or NTSB in connection with or subsequent to the release of the "preliminary report".

I thought the BEA and NTSB already had the FDR data. BEA were the ones who downloaded the FDR data, and they did not say that they did not look at the FDR data (as opposed to when the BEA said they did not listen to the CVR audio). NTSB assisted with downloading the FDR, so I assume they have a copy too.

Data from the FDR has been successfully downloaded by @BEA_Aero and transfered to the Ethiopian investigation team
https://twitter.com/bea_aero/status/1107292544868777984


Data from the CVR has been successfully downloaded by @BEA_Aero and transfered to the Ethiopian investigation team / communication on their behalf / @BEA_Aero did not listen to the audio files.
https://twitter.com/BEA_Aero/status/1107002307542159361


The U.S. National Transportation Safety Board is dispatching three investigators to France Thursday to assist with the downloading and analysis of flight recorders from the Boeing 737 MAX 8 that crashed Sunday near Addis Ababa, Ethiopia. - https://www.ntsb.gov/news/press-release ... 90314.aspx
 
WIederling
Posts: 9291
Joined: Sun Sep 13, 2015 2:15 pm

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Apr 01, 2019 9:02 am

XRAYretired wrote:
... the only leaks have come from un-named US officials to the WSJ (reprehensible?). Perhaps contrary to what you may think, these leaks tend to support MCAS being a significant contributor.


Aren't all involved parties bound by confidentiality?
i.e. they may only release information in accordance with the primary investigator?
( We've seen premature information release by US institutions in conjunction with the BA 777 fuel oil thingy. rules are for the lower ranks. )
Murphy is an optimist
 
XRAYretired
Posts: 870
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Apr 01, 2019 9:39 am

WIederling wrote:
XRAYretired wrote:
... the only leaks have come from un-named US officials to the WSJ (reprehensible?). Perhaps contrary to what you may think, these leaks tend to support MCAS being a significant contributor.


Aren't all involved parties bound by confidentiality?
i.e. they may only release information "released" by the primary investigator?
( We've seen premature information release by US institutions in conjunction with the BA 777 fuel oil thingy.)



Nods, nudges, winks, inflection of 'no comment' answers to direct questions and etc, all would be difficult to tie down and all used as tools in an otherwise open society.

I remember an older lad of mine got into a scrape with the police. I called the station to enqire as to his whereabouts and was told "I could not possibly tell you if he was in the police cell or not". The conclusion was inescapable! (no pun intended).

Ray
 
wjcandee
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Apr 01, 2019 9:57 am

flybucky wrote:
I thought the BEA and NTSB already had the FDR data. BEA were the ones who downloaded the FDR data, and they did not say that they did not look at the FDR data (as opposed to when the BEA said they did not listen to the CVR audio). NTSB assisted with downloading the FDR, so I assume they have a copy too.


I wouldn't assume that given that the US investigators are complaining that they don't have it.
 
jollo
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Apr 01, 2019 10:24 am

Etheereal wrote:
Excuse me, but AF447 lost ALL protections because all the pitot tubes froze. So you forgot that as well. (this message is directed to jollo btw).


Etheereal wrote:
Someone on the last 5 pages said something that there was ONLY one documented case of the A3XX series where the "sensors" all became unreliable, which im trying to say its false as there are at least 2 more examples, including AF447.


Excuse me, but that's not what we were discussing: we were listing documented occurrences of 2 bad but agreeing sensors outvoting the remaining good one and, therefore, the automation not disabling itself as it was designed to do. The point of the discussion is that competently-designed automations should disable automatically as soon as inputs are recognized as not reliable.

Alpha-prot on AF447 did exactly thas: disabled itself on invalid AoA data, as designed. Unfortunately, the crew then mishandled the aircraft, apparently disregarding the fact that they had lost stall protection (but who knows for sure what they were thinking?)

It might help the quality of the discussion to actually read posts before replying.

BTW, if anyone knows of other (than GXL888T and LH-1829) documented occurrences of fail-safe, triple-redundant designs where flight envelope protections did not disable automatically in case of a double sensor failure, please share. Thanks.
 
jollo
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Apr 01, 2019 12:05 pm

wjcandee wrote:
Well, the WSJ finally acknowledged today what I have been saying for weeks: you can't trust the pronouncements of the Ethiopian AIB about this. It is as likely to be total BS as it is likely to be factual:

"American air-safety officials also ... say the Ethiopians have provided often limited access to relevant crash information..." .


wjcandee wrote:
And that I am disinclined to take anything the Ethiopians say at face value. And again, nothing to do with who or where these folks are located, everything to do with their past actions.


I have already asked this question up-thread, but haven't seen any answer: what past attempts at obstruction of investigations is ET accused of? Not talking about ET-302, I suppose: I read about "past" and "often"-repeated foul-play episodes, but no references. Care to fill the gap? Sorry if already posted and I missed it.
Last edited by jollo on Mon Apr 01, 2019 12:21 pm, edited 1 time in total.
 
jollo
Posts: 395
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Apr 01, 2019 12:20 pm

jollo wrote:
Alpha-prot on AF447 did exactly thas: disabled itself on invalid AoA data, as designed.


Sorry, errata corrige: I should have written "disabled itself on invalid airspeed data, as designed.". Doesn't matter: the point here is that as soon as an essential input was detected as unreliable, the automation took itself off the control loop (as should be).
 
NOVAIAD
Posts: 51
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Apr 01, 2019 12:21 pm

PlanesNTrains wrote:
GalebG4 wrote:
Boeing you made a huge mistake. Accept it and get on with it, I don’t care about your airliners.net forum protectionists who will protect you no matter what. You made mistake, pay the families of the victims. Anybody could be in that plane(even you Boeing airliners.net forum protectionist- keyboard employee warrior) with uniformed pilots about system. This is your fault Boeing so stop being sneaky and trying to say we haven’t done anything wrong. You have, people died second time for the same reason.

Please don’t answer any Boeing airlines.net forum protectionists-keyboard warriors, because that’s spiting on people that have innocently died.


You’re great at casting stones. How about we wait for the investigation?



He can't hear you from inside his glass house.
 
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Finn350
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Apr 01, 2019 12:32 pm

wjcandee wrote:
flybucky wrote:
I thought the BEA and NTSB already had the FDR data. BEA were the ones who downloaded the FDR data, and they did not say that they did not look at the FDR data (as opposed to when the BEA said they did not listen to the CVR audio). NTSB assisted with downloading the FDR, so I assume they have a copy too.


I wouldn't assume that given that the US investigators are complaining that they don't have it.


From the WSJ article behind a paywall

Publicly, U.S. officials have expressed satisfaction with the sharing of information. Last Wednesday, Robert Sumwalt, chairman of the National Transportation Safety Board, which is leading U.S. participation in the probe, told a Senate subcommittee his experts have gotten the data they need.


https://www.wsj.com/articles/u-s-ethiop ... 1554073749

(The article can be accessed if searched though Google and clicking from there a link)
 
WIederling
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Apr 01, 2019 12:43 pm

Finn350 wrote:
Publicly, U.S. officials have expressed satisfaction with the sharing of information. Last Wednesday, Robert Sumwalt, chairman of the National Transportation Safety Board, which is leading U.S. participation in the probe, told a Senate subcommittee his experts have gotten the data they need.


https://www.wsj.com/articles/u-s-ethiop ... 1554073749

(The article can be accessed if searched though Google and clicking from there a link)


So what we saw elsewhere ( " investigation lead not sharing information because $corrupt!" ) is nothing else
but the regular run of character assassination so very popular in a certain domain.
Murphy is an optimist
 
WIederling
Posts: 9291
Joined: Sun Sep 13, 2015 2:15 pm

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Apr 01, 2019 12:51 pm

Finn350 wrote:
Publicly, U.S. officials have expressed satisfaction with the sharing of information. Last Wednesday, Robert Sumwalt, chairman of the National Transportation Safety Board, which is leading U.S. participation in the probe, told a Senate subcommittee his experts have gotten the data they need.


https://www.wsj.com/articles/u-s-ethiop ... 1554073749

(The article can be accessed if searched though Google and clicking from there a link)


So what we saw elsewhere ( " investigation lead not sharing information because $corrupt!" ) is nothing else
but the regular run of character assassination so very popular in a certain domain.
Murphy is an optimist
 
jollo
Posts: 395
Joined: Mon Aug 08, 2011 7:24 pm

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Apr 01, 2019 3:00 pm

Cross-posting member rheinwaldner from the B737MAX Grounded Worldwide thread (@Admins: sorry for bending the rules, but this is relevant).

++++++++

Here we have some credible statements, which are not hearsay because the name of the source is known (Rick Ludtke, a former Boeing designer, who worked on the MAXs cockpit interfaces):

Source is the following full copy of the original WSJ article, which is behind a paywall:
https://www.marketwatch.com/press-relea ... quote_news

More from Ludtke here:
https://www.seattletimes.com/business/b ... _inset_1.1

More statements from the following two links:
https://www.satcom.guru/2019/03/regulat ... stems.html
https://www.satcom.guru/2019/03/aoa-van ... g-fix.html


Statement 1: Penalty charges based on training requirements

Mr. Ludtke recalled midlevel managers telling subordinates that Boeing had committed to pay the airline $1 million per plane if its design ended up requiring pilots to spend additional simulator time. "We had never, ever seen commitments like that before," he said.



Statement 2: Pressure to implement no-additional-training solution
"Rick Ludtke, a former Boeing engineer who worked on designing the interfaces on the MAX’s flight deck, said managers mandated that any differences from the previous 737 had to be small enough that they wouldn’t trigger the need for pilots to undergo new simulator training."

"He said that if the group had built the MCAS in a way that would depend on two sensors, and would shut the system off if one fails, he thinks the company would have needed to install an alert in the cockpit to make the pilots aware that the safety system was off. And if that happens, Ludtke said, the pilots would potentially need training on the new alert and the underlying system. That could mean simulator time, which was off the table."


Statement 3: MCAS runaway hard to detect
For the first time, Boeing admits MCAS is an extension of Speed Trim, which I have long suspected, and why it was designed with a single input. Speed Trim is constantly applying stabilizer trim commands in manual flight. This masks MCAS trim commands. Further, MCAS trim commands are effectively a slowover and in the case of the Lion Air flights, intermittent. These factors, combined with the flight deck effects from the high AoA value causing high workload, interfere with the expected human response. There has yet to be any acknowledgement of this, rather the opposite by ignoring it. The FAA repeatedly made the same assertion, the MCAS malfunction is easy to detect.


And

As discussed in earlier posts, in fact MCAS failure is hard to detect as it is a slowover, and Speed Trim System (STS) applies automatic trim routinely, masking MCAS motion. JT043 only related the situation to a stab trim runaway after an observing pilot suggested it. JT610 crew never figured it out. It is possible ET302 flight crew did not detect the failure in spite of specifically be briefed to look for it. The situation was compounded by the AoA trigger of Stall Warning. Boeing should not assume so readily how pilots will perform when MCAS fails, while the evidence is in stark contrast.


Statement 4: After trim cutout, using the trim wheel may be inadequate to deal with the situation
The response to a stabilizer runaway is to cutout the electric trim. Nowhere does anyone caution the consequences of using manual (turn the wheel manually) trim. The manual trim wheel can be very hard to turn if subject to high aero loads, and particularly if the elevator is commanded significantly (loading the stabilizer).


Statement 5: Trim cut out checklist is flawed
The standard response to just hit the stabilizer cutout switches and manually trim is actually flawed. If the nose has been pushed down by significant mistrim (nose down stabilizer, nose up elevator), and as airspeed increases, it may not be possible to trim the stabilizer manually nose up without letting the elevator go to a neutral position. The reality, under the MCAS runaway scenario, trimming nose up immediately stops MCAS as well as trims the stabilizer back towards an in-trim position. At that point, you would be best off to cutout the stabilizer.
 
flybucky
Posts: 376
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Apr 01, 2019 3:39 pm

Preliminary Report release date changed again.

Ethiopia will not release a preliminary report into the causes of last month’s Ethiopian Airlines crash on Monday, as previously expected, but may publish it this week.

Ethiopia’s foreign ministry spokesman had earlier said the preliminary crash report would be released by the ministry of transport on Monday. It was not immediately clear why the plans had changed.

https://www.reuters.com/article/us-ethi ... SKCN1RD1PB
 
morrisond
Posts: 2662
Joined: Thu Jan 07, 2010 12:22 am

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Apr 01, 2019 3:42 pm

jollo wrote:
Cross-posting member rheinwaldner from the B737MAX Grounded Worldwide thread (@Admins: sorry for bending the rules, but this is relevant).

++++++++

Here we have some credible statements, which are not hearsay because the name of the source is known (Rick Ludtke, a former Boeing designer, who worked on the MAXs cockpit interfaces):

Source is the following full copy of the original WSJ article, which is behind a paywall:
https://www.marketwatch.com/press-relea ... quote_news

More from Ludtke here:
https://www.seattletimes.com/business/b ... _inset_1.1

More statements from the following two links:
https://www.satcom.guru/2019/03/regulat ... stems.html
https://www.satcom.guru/2019/03/aoa-van ... g-fix.html


Statement 1: Penalty charges based on training requirements

Mr. Ludtke recalled midlevel managers telling subordinates that Boeing had committed to pay the airline $1 million per plane if its design ended up requiring pilots to spend additional simulator time. "We had never, ever seen commitments like that before," he said.



Statement 2: Pressure to implement no-additional-training solution
"Rick Ludtke, a former Boeing engineer who worked on designing the interfaces on the MAX’s flight deck, said managers mandated that any differences from the previous 737 had to be small enough that they wouldn’t trigger the need for pilots to undergo new simulator training."

"He said that if the group had built the MCAS in a way that would depend on two sensors, and would shut the system off if one fails, he thinks the company would have needed to install an alert in the cockpit to make the pilots aware that the safety system was off. And if that happens, Ludtke said, the pilots would potentially need training on the new alert and the underlying system. That could mean simulator time, which was off the table."


Statement 3: MCAS runaway hard to detect
For the first time, Boeing admits MCAS is an extension of Speed Trim, which I have long suspected, and why it was designed with a single input. Speed Trim is constantly applying stabilizer trim commands in manual flight. This masks MCAS trim commands. Further, MCAS trim commands are effectively a slowover and in the case of the Lion Air flights, intermittent. These factors, combined with the flight deck effects from the high AoA value causing high workload, interfere with the expected human response. There has yet to be any acknowledgement of this, rather the opposite by ignoring it. The FAA repeatedly made the same assertion, the MCAS malfunction is easy to detect.


And

As discussed in earlier posts, in fact MCAS failure is hard to detect as it is a slowover, and Speed Trim System (STS) applies automatic trim routinely, masking MCAS motion. JT043 only related the situation to a stab trim runaway after an observing pilot suggested it. JT610 crew never figured it out. It is possible ET302 flight crew did not detect the failure in spite of specifically be briefed to look for it. The situation was compounded by the AoA trigger of Stall Warning. Boeing should not assume so readily how pilots will perform when MCAS fails, while the evidence is in stark contrast.


Statement 4: After trim cutout, using the trim wheel may be inadequate to deal with the situation
The response to a stabilizer runaway is to cutout the electric trim. Nowhere does anyone caution the consequences of using manual (turn the wheel manually) trim. The manual trim wheel can be very hard to turn if subject to high aero loads, and particularly if the elevator is commanded significantly (loading the stabilizer).


Statement 5: Trim cut out checklist is flawed
The standard response to just hit the stabilizer cutout switches and manually trim is actually flawed. If the nose has been pushed down by significant mistrim (nose down stabilizer, nose up elevator), and as airspeed increases, it may not be possible to trim the stabilizer manually nose up without letting the elevator go to a neutral position. The reality, under the MCAS runaway scenario, trimming nose up immediately stops MCAS as well as trims the stabilizer back towards an in-trim position. At that point, you would be best off to cutout the stabilizer.


The Boeing procedure in there bulletin released on Nov 6, 2018 was to use Electric Trim if necessary to return the plane to neutral or nose-up before hitting the cut-off switches if you did not want to use the manual system.
 
jollo
Posts: 395
Joined: Mon Aug 08, 2011 7:24 pm

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Apr 01, 2019 4:43 pm

morrisond wrote:
jollo wrote:
Cross-posting member rheinwaldner from the B737MAX Grounded Worldwide thread (@Admins: sorry for bending the rules, but this is relevant).

++++++++

Here we have some credible statements, which are not hearsay because the name of the source is known (Rick Ludtke, a former Boeing designer, who worked on the MAXs cockpit interfaces):

Source is the following full copy of the original WSJ article, which is behind a paywall:
https://www.marketwatch.com/press-relea ... quote_news

More from Ludtke here:
https://www.seattletimes.com/business/b ... _inset_1.1

More statements from the following two links:
https://www.satcom.guru/2019/03/regulat ... stems.html
https://www.satcom.guru/2019/03/aoa-van ... g-fix.html


Statement 1: Penalty charges based on training requirements

Mr. Ludtke recalled midlevel managers telling subordinates that Boeing had committed to pay the airline $1 million per plane if its design ended up requiring pilots to spend additional simulator time. "We had never, ever seen commitments like that before," he said.



Statement 2: Pressure to implement no-additional-training solution
"Rick Ludtke, a former Boeing engineer who worked on designing the interfaces on the MAX’s flight deck, said managers mandated that any differences from the previous 737 had to be small enough that they wouldn’t trigger the need for pilots to undergo new simulator training."

"He said that if the group had built the MCAS in a way that would depend on two sensors, and would shut the system off if one fails, he thinks the company would have needed to install an alert in the cockpit to make the pilots aware that the safety system was off. And if that happens, Ludtke said, the pilots would potentially need training on the new alert and the underlying system. That could mean simulator time, which was off the table."


Statement 3: MCAS runaway hard to detect
For the first time, Boeing admits MCAS is an extension of Speed Trim, which I have long suspected, and why it was designed with a single input. Speed Trim is constantly applying stabilizer trim commands in manual flight. This masks MCAS trim commands. Further, MCAS trim commands are effectively a slowover and in the case of the Lion Air flights, intermittent. These factors, combined with the flight deck effects from the high AoA value causing high workload, interfere with the expected human response. There has yet to be any acknowledgement of this, rather the opposite by ignoring it. The FAA repeatedly made the same assertion, the MCAS malfunction is easy to detect.


And

As discussed in earlier posts, in fact MCAS failure is hard to detect as it is a slowover, and Speed Trim System (STS) applies automatic trim routinely, masking MCAS motion. JT043 only related the situation to a stab trim runaway after an observing pilot suggested it. JT610 crew never figured it out. It is possible ET302 flight crew did not detect the failure in spite of specifically be briefed to look for it. The situation was compounded by the AoA trigger of Stall Warning. Boeing should not assume so readily how pilots will perform when MCAS fails, while the evidence is in stark contrast.


Statement 4: After trim cutout, using the trim wheel may be inadequate to deal with the situation
The response to a stabilizer runaway is to cutout the electric trim. Nowhere does anyone caution the consequences of using manual (turn the wheel manually) trim. The manual trim wheel can be very hard to turn if subject to high aero loads, and particularly if the elevator is commanded significantly (loading the stabilizer).


Statement 5: Trim cut out checklist is flawed
The standard response to just hit the stabilizer cutout switches and manually trim is actually flawed. If the nose has been pushed down by significant mistrim (nose down stabilizer, nose up elevator), and as airspeed increases, it may not be possible to trim the stabilizer manually nose up without letting the elevator go to a neutral position. The reality, under the MCAS runaway scenario, trimming nose up immediately stops MCAS as well as trims the stabilizer back towards an in-trim position. At that point, you would be best off to cutout the stabilizer.


The Boeing procedure in there bulletin released on Nov 6, 2018 was to use Electric Trim if necessary to return the plane to neutral or nose-up before hitting the cut-off switches if you did not want to use the manual system.


I believe you are intentionally focusing on a secondary detail to avoid addressing the gist of the statements above, which I find extremely troubling.

However, if you want to nitpick:
1) the stated Reason for the Nov 6th, 2018 bulletin (published after the Lion Air crash) is: "To Emphasize the Procedures Provided in the Runaway Stabilizer Non-Normal Checklist (NNC)", which is prefaced by this Condition: "Uncommanded stabilizer trim movement occurs continuously". Therefore the runaway stab NCC, and by extension the bulletin, should not apply to intermittent stab trim uncommanded movements (and mention of "repetitive cycles of uncommanded nose down stabilizer" in the "Background Information" section of the bulletin is confusing at best).
2) so basically Boeing was trying to tell pilots they have to use a procedure that calls for cutting off a malfunctioning servo but not too fast! - you first need to use that very servo to recover from an otherwise unrecoverable upset, and then you need to cut it off before it tries to kill you again. As a passenger, I would not want to fly on an airliner that relies on such procedures.
 
Backseater
Posts: 478
Joined: Fri Aug 19, 2005 3:20 pm

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Apr 01, 2019 6:01 pm

flybucky wrote:
Preliminary Report release date changed again.

Ethiopia will not release a preliminary report into the causes of last month’s Ethiopian Airlines crash on Monday, as previously expected, but may publish it this week.

Ethiopia’s foreign ministry spokesman had earlier said the preliminary crash report would be released by the ministry of transport on Monday. It was not immediately clear why the plans had changed.

https://www.reuters.com/article/us-ethi ... SKCN1RD1PB

I can understand why Ethiopia may need a bit more time to decide what to put in their Preliminary Report.

IMHO FDR & CVR are not the issues. They will clearly show that MCAS was active.
But rightfully so, and that may point to Ethiopian Airlines responsibility.

Are the maintenance records for that aircraft good enough to be released:
- serial numbers of the AoA sensors installed? (by the way, did they find them in the debris? They should have!)
- history records of the AoA sensors (source, repairs, ...)
- detailed records of the installation and test procedure of both sensors on that particular a/c
And if their maintenance records are not good enough, what will they do?

Notice that the Lion Air prelim was also vague in that area:
- no AoA serial numbers
- soon after they found the FDR and CVR, I think they basically stopped recovering more pieces, even though they are only 30m deep.
- "Installation test and heater system test result good." That is short! In another AMM, Being specifically says "Make a record of the left AOA sensor values" read with the ARINC 429 bus reader with the vane at 0, +90 and -90 degrees.
- "The investigation will perform several tests including the test of the AoA sensor and the aircraft simulator exercises in the Boeing engineering simulator." Which AoA sensor are they going to test? One that was recovered? Which one? Or one straight out of the factory?

It is easy to put all the blame on MCAS. But IMHO, the bigger problem may be in maintenance as I do not yet see a solution on the horizon.
 
fadecfault
Posts: 164
Joined: Mon Nov 05, 2007 8:44 pm

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Apr 01, 2019 6:09 pm

Backseater wrote:
fadecfault wrote:
Incorrect. There are 2 channels on the aoa. One feeds the symd and the other feeds the onside adiru which provides data to the onside fcc.
Stick shaker is only activated by the symd. Mcas is only activated by the active fcc.

Thank you for your corrections.
So, the 861FL1 has another analog channel to send sin & cos to the onside ADIRU? or is it sent digitally?
Where is the final AoA value elaborated?
Who puts the final AoA on the ARINC bus (so that the FDR can record it)?
When maintenance plugs an ARINC 429 bus reader to check one of the AoA sensors (I only assume they do because I do not have access to the AMM procedure), do they use a TEST ONLY connector on the onside ADIRU? Do they have another choice?


The AOA output/input is an analog dual channel configuration. No wires are shared but they seem to be bundled together in the forward equipment compartment.
AOA is calculated independently by the onside symd and onside adiru for their functions. I'm not sure which sends the aoa data to the FDR, no information is given and FDR data is not really line accessible. My guess is they both do.
The alternate ops test for the aoa directs you to use the symd to display the aoa angle.
The views and opinions written here are my own and do not reflect those of my employer.
 
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PixelFlight
Posts: 1018
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Mon Apr 01, 2019 6:16 pm

Backseater wrote:
fadecfault wrote:
Incorrect. There are 2 channels on the aoa. One feeds the symd and the other feeds the onside adiru which provides data to the onside fcc.
Stick shaker is only activated by the symd. Mcas is only activated by the active fcc.

Thank you for your corrections.
So, the 861FL1 has another analog channel to send sin & cos to the onside ADIRU? or is it sent digitally?
Where is the final AoA value elaborated?
Who puts the final AoA on the ARINC bus (so that the FDR can record it)?
When maintenance plugs an ARINC 429 bus reader to check one of the AoA sensors (I only assume they do because I do not have access to the AMM procedure), do they use a TEST ONLY connector on the onside ADIRU? Do they have another choice?

You can find a lot of details on the Satcom Guru blogs, for example:
https://www.satcom.guru/2019/03/aoa-van ... g-fix.html
https://www.satcom.guru/2018/11/737-fcc ... mmand.html

* While there are many documents showing AoA analog link to the SYMD, there aren't so much telling about the AoA link to the ADIRU, but it look like it's analog too.
* Depend on what you call "final AoA value". From the FCC point of view, this is the ADIRU.
* The ADIRU send the AoA value on the ARINC bus for the FCC.
:stirthepot: 737-8 MAX: "For all speeds higher than 220 Kts and trim set at a value of 2.5 units, the difficulity level of turning the manual trim wheel was level A (trim wheel not movable)." :stirthepot:

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