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MAXís Return Delayed by FAA Reevaluation of 737 Safety Procedures

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MAXís Return Delayed by FAA Reevaluation of 737 Safety Procedures

Old 7th Dec 2019, 22:53
  #4321 (permalink)  
 
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From the linked report, a statement by Dennis Muilenberg:
“If we do not coordinate this [return to service] we may see some disaggregation, and I don’t think that’s a future any of us wants to see.”
An unfortunate choice of words in this context.

disaggregate:to separate into component parts
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Old 7th Dec 2019, 22:57
  #4322 (permalink)  
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Originally Posted by India Four Two View Post
An unfortunate choice of words in this context.
Well, you know, it makes perfect sense to sort out the reusable stuff before the big pieces go to the aluminum shredders.
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Old 8th Dec 2019, 00:18
  #4323 (permalink)  
 
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Originally Posted by OldnGrounded View Post
Thanks.

From the linked report:



But . . . that describes the case for the first revised version of MCAS (rapid movement of stab up to 2.5 units), not the situation the system was initially designed to address (allegedly, stick force gradient in wind-up turns).

Maybe Mr. Bomben forgot.

Uhhh note the date of the report - July

The best description of the ' explanation ' Is " and the farmer hauled another load away .."
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Old 8th Dec 2019, 00:30
  #4324 (permalink)  
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Originally Posted by Grebe View Post
Uhhh note the date of the report - July
Oops. I followed the link thinking it was from the recent meeting . . . and started skimming for interesting stuff.

The best description of the ' explanation ' Is " and the farmer hauled another load away .."
Yup.

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Old 8th Dec 2019, 00:34
  #4325 (permalink)  
 
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Originally Posted by PHDracing View Post
I know there are only a few days until the end of the quarter and maybe that will bring a reckoning.....But I remain impressed (or amazed) at the strength of BA stock.
Close today at $354....Give this company some good news.....like the Max will fly again......and this stock will run!

What do the Pros say? Well, Reuters, Ned Davis, Morningstar, Credit Suisse, etc....all are "neutral" for BA's future.......With people like Market Edge Second Opinion saying to Buy and hold for the long term!

Of the other hand.....Charlie Schwab gives them a rating of F. STRONGLY UNDERPERFORM.....Charlies lowest rating.

I wouldn't touch them with "your money".....but I am impressed at how strong the stock is.... considering all the bad news. IF and that's a might big IF.....you believe they will straighten out and fly right........
This could be a nice play.

Last edited by dozing4dollars; 8th Dec 2019 at 01:08. Reason: Addictive to enhance readability
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Old 8th Dec 2019, 00:55
  #4326 (permalink)  
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the one comment I like from above posts is a MCAS warning light, similar to the STAB OUT OF TRIM light, crude but simple.
And pressing it to stop that piece of software running would be a nice addition.

Craig Bomben,
“We’ve moved from a very simple system to an intelligent system.”
Okay, but Airbus took years to develop their HAL. This seems a limited time to develop a sapient being.

But if it is correctly triggered, the system now “operates only once per AoA event”, according to Bomben, and when it does trigger stabiliser movement, it memorises how much displacement has taken place, so if it were triggered again it would take account of existing stabiliser displacement and will not apply more than a safe cumulative limit.
Now define a single AoA event.
FAA regulations require that one of the cues to the pilot of the approaching stall is that the stick force should increase at a linear rate as the airspeed decreases and the angle of attack increases. FAA regulations require that one of the cues to the pilot of the approaching stall is that the stick force should increase at a linear rate as the airspeed decreases and the angle of attack increases. In the Max, however, at a certain point in this sequence the centre of lift shifts forward a little, providing a slight nose-up pitch force, therefore the stick force does not continue to increase, so MCAS is designed to kick in with some nose-down trim to restore the linear increase.
By comparison, does the NT stick force (needed) actually increase, or just not get lighter so quickly? There has been strong inference that the MAX gets unacceptably and specifically lighter.
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Old 8th Dec 2019, 01:18
  #4327 (permalink)  
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Originally Posted by Loose rivets View Post
Now define a single AoA event.
Excellent point of inquiry.

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Old 8th Dec 2019, 06:57
  #4328 (permalink)  
 
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Originally Posted by Grebe View Post
From the view of this interested SLF re yoke-column cutout switch. Believe you may be missing a point. AFIK ALL NG versions for the last several decades had operable yoke cutout swiches such that if pilot pulled yoke in muscle memory reaction to a sudden or noticeable AND ( dive), pulling the yoke would stop- disconnect the stabilizer, and unless another improbable fault happened, the stabilizer would stop moving and the elevator trim switches would still work. Sort of like if your car due to a flat tire swerves to right or left, your immediate reaction ( unless on smart phone ) would be to twist wheel in opposition.

The pilots in both Lion and Ethopia were never told that the addition of MCAS ( aka HAL ) essentially bypassed that switch. And if they did NOT regain near neutral ( level ) trim before using console cutout switches which cut all power to switches and autopilot and ??, the manual trim wheel was essentially unuseable. And as I recall, one of the recordings showed that a few seconds before flight termination, both pilots were pulling back maximum forc on the yoke which IF in the NG would have stopped the stabilizer AND still left the electric trim switches operable.

Just my armchair opinion
Grebe, respectfully, but is that correct? From my FCOM

Control column actuated stabilizer trim cutout switches stop operation of the main
electric and autopilot trim when the control column movement opposes trim
direction. When the STAB TRIM override switch is positioned to OVERRIDE,
electric trim can be used regardless of control column position

It would appear to me that moving the CC in a direction opposite the trim(actuating the control column cut out switches) would stop ALL electric trim! Also the control column trim switches!

Often arriving in an airplane with electrice HYD pumps off with the control column slightly aft, trying to reset the trim to approx 5 units during preflight(as my collegeís didnít do so during taxi in), this is not possible with the control column trim switches until I push the control column slightly forward.

that is also the reason we have the STAB TRIM override switch I thought.

greetings.
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Old 8th Dec 2019, 07:55
  #4329 (permalink)  
 
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Is it correct that Max airframes will need new engines fitted before a return to flight? I thought they had been kept running during the down-time.
Provisional bookings for Hangar space under discussion.
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Old 8th Dec 2019, 10:40
  #4330 (permalink)  
 
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[QUOTE=Loose rivets;10634623]And pressing it to stop that piece of software running would be a nice addition.

A bit like Norman Tebbits' Jesus Christ Switch=left[Lord Tebbit points to a large handle on the ceiling of the cockpit in a Bristol Britannia] = Lord Tebbit : It was the first really very, very electrical aeroplane. But that had a downside, of course, in that if you lost the electrics you were in real big trouble. That's when this switch came in. And basically it would disconnect all the generators and then reconnect them again. And you should get at least *some* of your electrical services back again. It was known, inevitably, as the Jesus Christ switch, because that was the only occasion when you'd use it, at that moment when everybody on the flight desk was saying "Jesus Christ!". And you'd grab it and hopefully all power would be restored. Very useful!

I think I posted this some time ago, but perhaps Boeing need reminding.
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Old 8th Dec 2019, 13:40
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Originally Posted by blue up View Post
Is it correct that Max airframes will need new engines fitted before a return to flight? I thought they had been kept running during the down-time.
Provisional bookings for Hangar space under discussion.

I don't think that is very likely or indeed necessary
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Old 8th Dec 2019, 14:53
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Originally Posted by flyburg View Post


Grebe, respectfully, but is that correct? From my FCOM

Control column actuated stabilizer trim cutout switches stop operation of the main
electric and autopilot trim when the control column movement opposes trim
direction. When the STAB TRIM override switch is positioned to OVERRIDE,
electric trim can be used regardless of control column position

It would appear to me that moving the CC in a direction opposite the trim(actuating the control column cut out switches) would stop ALL electric trim! Also the control column trim switches!

Often arriving in an airplane with electrice HYD pumps off with the control column slightly aft, trying to reset the trim to approx 5 units during preflight(as my college’s didn’t do so during taxi in), this is not possible with the control column trim switches until I push the control column slightly forward.

that is also the reason we have the STAB TRIM override switch I thought.

greetings.

This SLF will of course defer to a pilot.. But from my reading and understanding, you have described how an NG works and has worked for a few decades. Suggest you take a look at
https://www.satcom.guru/2019/10/flaw...-disaster.html
plus a half dozen other detailed of his detailed posts on the issue of MAX.

Also
https://leehamnews.com/2019/11/01/bj...-crash-part-1/ and now up to 6

https://leehamnews.com/2019/11/29/bj...-crash-part-5/


https://leehamnews.com/2019/12/06/bj...-crash-part-6/


And in simple terms ( as I undeerstand ) the MAX-MCAS system version 1.0 used on Lion and Ethopia had changed the description and function of the lower Console cutout switches such that both were in series, and either one cut all electric trim power and all autopilot power- thus were/are labeled PRI and B/U- and the ONLY method of moving stab was the (in)famous manual trim wheel.

And also sat guru wiring diagram on MAX shows MAX bypassed column/yoke ' mounted' cutout switch such that when yoke moved opposite to stab movement, nothing happened- eg stab movement was NOT stopped. Thus we have MCAS system acting like HAL .. .

Last edited by Grebe; 8th Dec 2019 at 15:02. Reason: added links
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Old 8th Dec 2019, 15:25
  #4333 (permalink)  
 
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@ Grebe,

ok, thanks for the clarification!

greetings
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Old 8th Dec 2019, 16:30
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Originally Posted by PHDracing View Post
What do the Pros say? Well, Reuters, Ned Davis, Morningstar, Credit Suisse, etc....all are "neutral" for BA's future.......With people like Market Edge Second Opinion saying to Buy and hold for the long term.
Well you are entitled to your opinion about the "pros". I have found their statements through this situation anything but accurate, going back to the earlier days. Time was when the, extraordinarily highly paid, pros would have good insight, whereas progressively over time they have been infiltrated by lobbyists etc and now just seem a conduit for press releases. Still highly paid but it makes the job easier. Boeing has produced financial forecasts but nothing I've seen comments in detail on their free cash flow, and presumably their share buy-backs are a dead duck for now.

I expect it may start to change after January. We may notice forward orders for Boeing have dried up.

I still don't understand how Boeing, who must have strings of BRILLIANT aeronautical engineers, could not get this one tied up within weeks of the grounding, yet here we are the best part of a year afterwards. Is there some internal turf war going on over whose solution or whose budget is going to manage this.

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Old 8th Dec 2019, 17:02
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Originally Posted by WHBM View Post

I still don't understand how Boeing, who must have strings of BRILLIANT aeronautical engineers, could not get this one tied up within weeks of the grounding, yet here we are the best part of a year afterwards. Is there some internal turf war going on over whose solution or whose budget is going to manage this.
Because for the first time ever 20 + yrs worth of klufges and work arounds dating back to the first 737NG, got a good looking at.......and the results were not pretty. The 737 is certified under the regulations that existed in 1967, those regulations ignored/allowed stuff that is now considered completely unacceptable. Getting the existing mish mash of technology to be compliant is, I would suggest, a lot harder than starting from scratch.

Tome the ultimate irony is a complete upgrade of the cockpit and flight control technology was going to add 1 year to the Max development schedule and cost up to 10 Billion extra dollars. It was rejected out of hand at the project kick off yet here we are, grounded for at lest a year and the bill to Boeing is 8.3 Billion and rising.......
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Old 8th Dec 2019, 17:40
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Originally Posted by Grebe View Post
Uhhh note the date of the report - July
Nope, although the confusion is understandable. British numeral dates are day-month-year.

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Old 8th Dec 2019, 18:09
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Originally Posted by LowObservable View Post
Nope, although the confusion is understandable. British numeral dates are day-month-year.
mea culpa - but for Bomb... to give that explanation at this late date is even worse. Virtually all the previous explanations starting in march referred to the high speed high altitude windup turn with aft CG being the driving issue and the initial Airspeed and g load restrictions such that only .6 or so degrees of stab motion needed. It was the low spped, low altitude issue which resulted in the 4 times stab motion to push nose down . .

Back to the ' lies, damm lies, and statistics mantra


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Old 8th Dec 2019, 18:25
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Originally Posted by Grebe View Post
mea culpa - but for Bomb... to give that explanation at this late date is even worse. Virtually all the previous explanations starting in march referred to the high speed high altitude windup turn with aft CG being the driving issue and the initial Airspeed and g load restrictions such that only .6 or so degrees of stab motion needed. It was the low spped, low altitude issue which resulted in the 4 times stab motion to push nose down . .

Back to the ' lies, damm lies, and statistics mantra
Confused me, too, when I went back and looked at the date. I forgot that Learmount is a Brit. (Reminder to self: Use month names when international readers might be confused. "7 December" or "December 7th" are equally clear to all.)

Regardless, whatever the timing of Craig Bomben's fundamentally-inaccurate explanation, it indicates either than he doesn't know how MCAS developed or he was deliberately speaking something less than the truth. I'm not quite certain which possibility is more alarming.
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Old 8th Dec 2019, 18:25
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Originally Posted by Big Pistons Forever View Post
To me the ultimate irony is a complete upgrade of the cockpit and flight control technology was going to add 1 year to the Max development schedule and cost up to 10 Billion extra dollars. It was rejected out of hand at the project kick off yet here we are, grounded for at lest a year and the bill to Boeing is 8.3 Billion and rising.......
Yes, but until the bill for the grounding and its consequences actually gets above $10 bn, Boeing stockholders are still laughing ...
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Old 8th Dec 2019, 18:28
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Originally Posted by DaveReidUK View Post
Yes, but until the bill for the grounding and its consequences actually gets above $10 bn, Boeing stockholders are still laughing ...
You mean, ". . . until Boeing stockholders realize the bill is above $10 billion," Dave. 'Cuz the chances that it's not already there are, as they say, slim and none.
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