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Boeing 737 Max Software Fixes Due to Lion Air Crash Delayed

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Boeing 737 Max Software Fixes Due to Lion Air Crash Delayed

Old 25th Apr 2019, 21:48
  #781 (permalink)  
 
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One possibility being floated: a compromise that mandates simulator training within a certain timeframe, but not as a precursor to flying the MAX. This would allow airlines to work MCAS scenarios into planned simulator training sessions, minimizing training disruption
.
I can't see any certification body, other than the FAA, regarding such an approach with anything other than complete ridicule.
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Old 25th Apr 2019, 22:34
  #782 (permalink)  
 
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Originally Posted by WHBM View Post
.
I can't see any certification body, other than the FAA, regarding such an approach with anything other than complete ridicule.
It would be surprising if any authority accepted a MCAS fix that required ‘failure training’.
Any system which has access to trim requires robust protection; if this is deemed insufficient in extreme circumstance, such as existing runaway trim scenarios, then training for these should have greater focus, but such training would not be MCAS specific.
MACAS experience might be required to provide awareness of aircraft ‘feel’ (pitch manoeuvring) in the few sections of the flight envelope which require MCAS to improve stability, but would be unavailable due to the AoA lockout logic post mod

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Old 25th Apr 2019, 23:52
  #783 (permalink)  
 
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Salute!

Well, PEI, I am surprised that Boeing does not have to do some aero model work and not use a kludge doofer to meet the cert requirements for back stick force and aircraft pitch moment versus AoA near the stall portion of the envelope.
Worse, one reference we have seen here states that MCAS was directed toward the other end of the envelope than right after takeoff. So any inquisitive pilot might have seen an MCAS reference and didn't relate a problem if the thing went apeshit right after takeoff.
And then not realizing that a bad AoA vane would trigger both the stall shaker and the unreliable speed warning and then the ........ GASP!!
I flew three really neat new planes in their first year of operational use, and we were "test pilots" as a matter of course. Realize that some dweebs have to be the first folks who are not "golden arms" from Edwards are gonna fly the things. . Regardless of all the great engineer work, the planes and the pilots found new things that needed work. But this Boeing implementation takes the cake, and I am still not sure what I would have done other than the flight preceding the fatal Lion one. i.e. if my stick trim worked, I prolly would have eventually turned off the electric trim. But would I have known that the "runaway" trim was due to MCAS plus a bad vane? I don't think so. But in my old, shriveled brain I feel I would have eventually turned off stuff. Then again..... Whole thing sucks, and that's my story and I am sticking to it.

Gums sends...
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Old 26th Apr 2019, 05:01
  #784 (permalink)  
 
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Originally Posted by 737 Driver View Post


I have been searching high and low for any actual cases of this happening on the 737NG, particularly as a result of a bad AOA or airspeed input in much the same way as occurred in the MAX accidents. If anyone has an actual case history of this malfunction, please post it here or send me a PM.
You might look into Egypt Air flight 990 that crashed into the Atlantic. The official ruling was pilot suicide but there are people that disagree. It seems that to loose 33,000 feet in less than 40 seconds is beyond pilot control. ( if i am reading this right)
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Old 26th Apr 2019, 05:11
  #785 (permalink)  
 
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Salute!

Losing altitude?

Look at the final seconds of the Atlas 767. Some links on PPRuNe. Just 350 to 400 knots will get you over 1,000 feet per second.

Gums...
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Old 26th Apr 2019, 05:50
  #786 (permalink)  
 
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Originally Posted by Arydberg View Post
You might look into Egypt Air flight 990 that crashed into the Atlantic. The official ruling was pilot suicide but there are people that disagree. It seems that to loose 33,000 feet in less than 40 seconds is beyond pilot control. ( if i am reading this right)
Aside from that being a 767, and not a 737NG, if you read the actual report you'd almost have to be delusional to believe it wasn't pilot suicide.
Unless you actually believe that a pilot, in the middle of an emergency, would reach down and move both engine fuel levers to CUTOFF in an effort to save the aircraft....
I wasn't directly involved in the investigation, but I know several people who were. We're not talking the engines just quitting (due, perhaps, to the negative G starving them of fuel). Fuel lever position is on the DFDR, and they both changed state to CUTOFF at about the same time.
If anything remotely positive came out of the Germanwings crash, it's that Lubitz proved beyond any reasonable doubt that pilot suicide is a real threat.
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Old 26th Apr 2019, 10:20
  #787 (permalink)  
 
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Originally Posted by WHBM View Post
.
I can't see any certification body, other than the FAA, regarding such an approach with anything other than complete ridicule.
Fixing MCAS is like a fresh set of paint. We need to fix the system that caused MCAS. ...and only once we have fixed the systemic failure - then we need to review all outcomes produced by the failed system, like MCAS.
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Old 26th Apr 2019, 14:14
  #788 (permalink)  
 
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Originally Posted by gums View Post
Just 350 to 400 knots will get you over 1,000 feet per second.
mph to feet per second = x 1.5 (close-ish). Ah yes, 30mph = 44fps, possibly exactly.

Other handy one is mph to meters per second = x 0.5 but that is not so close,however good enough for a bit of hand waving.

I leave the knots to mph to you:-)

Thanks for all your thoughtful posts.

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Old 26th Apr 2019, 14:50
  #789 (permalink)  
 
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You may be totally right. I only know the Egyptians do not agree. He was bringing tires back to a family member.
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Old 26th Apr 2019, 14:52
  #790 (permalink)  
 
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Originally Posted by gums View Post
Salute!

Well, PEI, I am surprised that Boeing does not have to do some aero model work and not use a kludge doofer to meet the cert requirements for back stick force and aircraft pitch moment versus AoA near the stall portion of the envelope.
Worse, one reference we have seen here states that MCAS was directed toward the other end of the envelope than right after takeoff. So any inquisitive pilot might have seen an MCAS reference and didn't relate a problem if the thing went apeshit right after takeoff.
And then not realizing that a bad AoA vane would trigger both the stall shaker and the unreliable speed warning and then the ........ GASP!!
I flew three really neat new planes in their first year of operational use, and we were "test pilots" as a matter of course. Realize that some dweebs have to be the first folks who are not "golden arms" from Edwards are gonna fly the things. . Regardless of all the great engineer work, the planes and the pilots found new things that needed work. But this Boeing implementation takes the cake, and I am still not sure what I would have done other than the flight preceding the fatal Lion one. i.e. if my stick trim worked, I prolly would have eventually turned off the electric trim. But would I have known that the "runaway" trim was due to MCAS plus a bad vane? I don't think so. But in my old, shriveled brain I feel I would have eventually turned off stuff. Then again..... Whole thing sucks, and that's my story and I am sticking to it.

Gums sends...
Do you consider the Speed Trim system to be a "kludge doofer"? If not why not - it has considerably greater authority than MCAS and in the same part of the flight envelope. Why aren't you deriding this too, especially as it seems Boeing regarded MCAS as a fairly minor componnet within the speed trim system?

The MCAS didn't go apesh!t "right after take off". It ran away after flap retraction. That's quite an important distinction, don't you think?

What possible use - let alone imperative as you seem to imply - is it to know what caused the runaway, be it MCAS or Uncle Tom Cobbley's sandwich wrapper in the works? Runaway trim is runaway trim, so just carry out the memory items. Let the engineers worry about the whys and wherefores.
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Old 26th Apr 2019, 15:53
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Salute!

Yes, I do place STS as a bandaid to overcome crappy speed/AoA stability characteristics. The basic airframe should meet the cert without help from HAL.

Secondly, I cannot seem to find a memory item for initial response to stick shaker that requires nose up trim or turning off electric trim. Or pulling off power, or.....

Good and great airmanship has saved many SLF, but there are times the deck is stacked against you, and either the procedure does not apply or work. And in three of my close calls there WAS NO PROCEDURE.

So I shall continue to grant the crews some slack and whine about a crappy design and implementation that got thru all the hoops to be fielded.

Gums opines...
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Old 26th Apr 2019, 17:34
  #792 (permalink)  
 
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Originally Posted by GlobalNav View Post
Zero cost, since there are none for the accident aircraft.
Huh? Are you two being serious? I don’t get the joke otherwise. On the odd chance that you don’t know, lookup “wrongful death lawsuit” on google. For example, dependents have the right to expect a certain amount of income from their spouse/parent which has now been wrongfully denied them. Same general principle as losing expected income because you were supplied a defective product. (Not a lawyer)
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Old 26th Apr 2019, 18:26
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Originally Posted by Water pilot View Post

Huh? Are you two being serious? I don’t get the joke otherwise. On the odd chance that you don’t know, lookup “wrongful death lawsuit” on google. For example, dependents have the right to expect a certain amount of income from their spouse/parent which has now been wrongfully denied them. Same general principle as losing expected income because you were supplied a defective product. (Not a lawyer)
There were no survivors in either crash. Therefore, there are no 'families of survivors' to litigate.
That is the reason for the response.

For those that died there are Warsaw Convention limits on damages that can be claimed.
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Old 26th Apr 2019, 19:22
  #794 (permalink)  
 
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Ah, I see. It seems a bit in poor taste to be playing on words like this when hundreds of our fellow humans who are properly called "surviving family members" who are grieving the loss of their spouse, parents, or children, a pain that never really goes away.
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Old 26th Apr 2019, 20:09
  #795 (permalink)  
 
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STS comment
______________________________
Salute!
my comment re: STS was based upon the FCOM description I have and FCeng84 comments and most inportantly, the log entry if the Lion flight that preceded the fatal one.

The pilot stated that the STS was working backwards. Yep. Sucker should have been trimming nose up as speed increased, right?. Of course,he was dealing with the shaking yoke and a slew of warning lights. Still did a great job for longer than most of us.

I can understand a good design that has a bit less speed/AoA stability than older planes like the DC-3, Constellation, 707, and on. We even have "help" for coping with dutch roll and such via our yaw dampers and even pitch dampers on some planes. But seems to me that the 737 either needs a waiver and not a kludge system that is implicated in two fatal accidents, or the FAR requirements need to be improved.

Someplace on PPRuNe there's a story of the initial Airbus FBW certification and how the speed stability issue was handled. Unless you flew the thing in "direct law", the control laws were doing all kinds of things to "help" you. Most important is that the 'bus was certified with no feedback of any kind to the control stick. You can pull back at any speed and have zero "feel" for the aero forces on your elevator or having to use more deflection at high AoA. Need a 'bus driver here, as actual stick displacement might have a different slope depending on AoA. i.e. at high AoA it might take more degrees of displacement for the same AoA change as at low AoA, even though the system is basically a gee command with attitude components.

Gums.....
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Old 26th Apr 2019, 20:39
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That's correct Gums, just a simple spring, no feedback or any tension adjustment for anything.

It's not an issue at all.

​​​​​​Direct law 320 sim flies far nicer than actual 738.
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Old 27th Apr 2019, 00:44
  #797 (permalink)  
 
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Originally Posted by Water pilot View Post

Huh? Are you two being serious? I don’t get the joke otherwise. On the odd chance that you don’t know, lookup “wrongful death lawsuit” on google. For example, dependents have the right to expect a certain amount of income from their spouse/parent which has now been wrongfully denied them. Same general principle as losing expected income because you were supplied a defective product. (Not a lawyer)
Sorry for the misunderstanding. No survivors to sue, just related family members. And you're right, humor is not necessary, my bad.
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Old 27th Apr 2019, 01:36
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Salute!

Thanks, Cland......

What a lotta folks do not understand about FBW is that it can be implemented with zero computer help. It can be a simple pair of wires to a control actuator that replaces levers, pulleys, cables, pushrods, etc. Most FBW systems have a hydraulic source that the wires activate or control. But some are now being flown that use the electricity in the wires to move the control surfaces, and the new F-35 is one of those.

What the FBW system architecture allows is sorta like a cosmic autopilot with all kinds of "help" to reduce workload and make for a smooth flight. For example, flying thru bumpy air is smoother because the rate and gee sensors act very quickly to command the surfaces before a human could react. The Viper felt like a much bigger and heavier plane when down low on hot days with thermals all over.

Gums sends...



.
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Old 28th Apr 2019, 13:26
  #799 (permalink)  
 
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Max Software fixes delayed, Infinitely!?

I find this latest development from Boeing and FAA fascinating.
They push the MCAS software patch without sim training as if they have fixed the problem.
Only to possibly admit a short sim addition and off we go!

There is just a few problems with this and I will list the biggest.
1 The aircraft is not stable and MCAS does not make it more stable or more stall proof, ie not certifiable!
2 The AOA indicator is flawed and if not corrected will in the future potentially cause a fatal accident on its own.
3 From a CRM stand point I can make a case of particularly edgy, but average crew ,getting into a full stall after a "normal " MCAS activation!
( ie Pulling and trimming ANU close to stall if not properly trained in a sim)
4 If Boeing has not developed an aerodynamic fix on the tail to counter the engine cowling induced pitch up at higher AOA in parallel with the MCAS patch to replace it , we risk the commercial pressure to overrule the basic certification criteria.

If Boeing get away with the MCAS Light without any sim training as is most likely, law and order is abandoned.
In particular the respect and fear of Newton and Bernoulli, in which we keep in balance every day.
History will judge harshly on Our choice.
Sincerely
CptB
Future MAX pilot!?
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Old 28th Apr 2019, 15:45
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Originally Posted by Arydberg View Post
You might look into Egypt Air flight 990 that crashed into the Atlantic. The official ruling was pilot suicide but there are people that disagree. It seems that to loose 33,000 feet in less than 40 seconds is beyond pilot control. ( if i am reading this right)
Not necessarily. TWA841 comes to mind. Lost 34,000 feet. I had two co-workers on that flight - both thought they were toast.

Last edited by b1lanc; 28th Apr 2019 at 15:59.
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