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MAX’s Return Delayed by FAA Reevaluation of 737 Safety Procedures

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MAX’s Return Delayed by FAA Reevaluation of 737 Safety Procedures

Old 1st Oct 2019, 04:47
  #2781 (permalink)  
 
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from the above post
Boeing CEO sees ‘endgame’ in effort to lift grounding of 737 MAX
Sep. 30, 2019 at 9:30 am Updated Sep. 30, 2019 at 4:24 pm
By Julie Johnsson
Bloomberg

The company’s accident-investigation team, safety-review boards and engineering and technical experts who represent the Federal Aviation Administration in aircraft certification will all report to Pasztor, who previously oversaw product safety at Boeing’s jetliner division.
Does anyone see the problem with the above ' system' of reporting? What has changed since previous issues re reporting to FAA THRU Management ?

The same ODA versus DER game with new covering.

Will the dissenters at Boeing please pick up the 30 inch diameter wearable target with the red circles which match the same stamp on your personnel file ?

Hang it on your back - a bit lower

Thank you !

Obviously ONLY a software fix is contemplated- just like he said last march or was it jan ?

Last edited by Grebe; 1st Oct 2019 at 04:51. Reason: Added software issue
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Old 1st Oct 2019, 05:24
  #2782 (permalink)  
 
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Originally Posted by OldnGrounded View Post
Hmmm, indeed. It's really inconceivable that friction between the jackscrew and the ball nut could even come close to the axial forces transmitted from aero loads on the stabilizer.
I was thinking that even axial forces could increase the friction between the ball nut and the screw. I know a ball nut has much lower friction compared to a regular nut, but I'm not sure how it would behave under large axial loads. But I could be wrong about that, and friction caused by axial loads might indeed be insignificant.

The problem is, if there is no significant friction increase when there is an axial load, then I would expect to be much easier to trim in the AND direction when you already have an AND mistrim. And the more out of trim you are, the easier it should be to apply more trim in the wrong direction. But Mentour's simulator video has shown otherwise, the more AND mistrim they had, the harder it became to trim AND (and ANU) manually.

Assuming the simulator replicates the behavior correctly, if it's not the friction in the nut that causes this behavior, then maybe the behavior is caused by some strange interaction with the braking mechanism that prevents the screw from being back driven.
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Old 1st Oct 2019, 07:43
  #2783 (permalink)  
 
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A ball nut acts very much like a thrust ball bearing, the difference being that the race is slightly oblique.
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Old 1st Oct 2019, 07:51
  #2784 (permalink)  
 
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Originally Posted by hans brinker View Post
I can think of at least 5 cities with 200K+ people with an elevation over 5000', that will have 35deg C+ temperature over the summer.
To my knowledge, the highest significantly large US airport is Colorado Springs at 6,100 ft.
Addis Ababa is very significantly higher, at almost 7,700 ft; that is not the same thing at all....

By the way, I do not find the details of the trade case cited in this paper https://www.thejakartapost.com/news/...airports-.html, but it would be interesting to read it...

.
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Old 1st Oct 2019, 07:52
  #2785 (permalink)  
 
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This whole saga can probably be boiled down to these two quotes:

This is an engineering company, it needs an engineering culture and engineering management,” aerospace analyst Richard Aboulafia said last week. “It deviated pretty far from this at the time when the Max was being developed
The U.S. National Transportation Safety Board last week called for a renewed focus on how a cacophony of flight-deck alerts can distract and overwhelm pilots. The agency’s report on the Max tragedies also provided clues to one of the mysteries of the disasters: how Boeing safety assessments for a software-system linked to the crashes could still comply with FAA design principles.
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Old 1st Oct 2019, 07:53
  #2786 (permalink)  
 
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Originally Posted by Grebe View Post

" The company’s accident-investigation team, safety-review boards and engineering and technical experts who represent the Federal Aviation Administration in aircraft certification will all report to Pasztor, who previously oversaw product safety at Boeing’s jetliner division."

Does anyone see the problem with the above ' system' of reporting? What has changed since previous issues re reporting to FAA THRU Management ?

The same ODA versus DER game with new covering.

[...]

Obviously ONLY a software fix is contemplated- just like he said last march or was it jan ?
Interesting.
Viewed from outside, indeed nothing has changed at Boeing.
Persuading the public to board the aircraft might prove difficult...

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Old 1st Oct 2019, 09:11
  #2787 (permalink)  
 
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Tomaski, #2746
‘… a conflict between theory and reality.‘
Humans tend to categorise solutions as either-or, true-false, which in the digital age reinforced with binary thinking.
The reality which we seek is a compromise; the world is uncertain and thus solutions involve managing uncertainty. An alternative definition of risk is the degree of uncertainty which an operator has to manage; forward-looking thinking, opposed to statistical hindsight.

“Man and machine” together, viewed as a system where each element is used proportionately and playing to their strengths.
From this viewpoint the 737 Max could be, and has in this forum, been criticised for misjudged technical uncertainty, and an an unbalanced solution with respect to human intervention (also see NTSB report).

‘… QRC procedures I referenced above, at least five of them have not been presented to me in the sim since my initial checkout some years ago.’

This is a concern; however having encountered the same situation from a serious incident investigation and the regulator, the opinion for ‘Red’ level action was such practice was not to be assumed, nor required (mandated). From this there was a mismatch between what the manufacturer - certification regulator assumed, and the operational - training regulator expected.
‘Egg-box management (ivory towers); is this too an aspect of recent FAA activity.

‘… the key to avoiding the manual trim problem in the 737 is prompt recognition and response.’
I disagree. There could be a suitable balance, providing that with consideration of a range of human contribution - delay / distraction, results in a situation which could still be recovered albeit with great difficulty.
However, it appears that with the Max the trim system can runaway (not MCAS) to a position which in some situations cannot be recovered. This inability is not allowed in certification, particularly when considerating likely human performance. I suspect that this is an aspect of current international discussions - a compromise, a judgement, and uncertainty.

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Old 1st Oct 2019, 09:17
  #2788 (permalink)  
 
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https://www.abc.net.au/news/2019-10-...rings/11560082


The first of six Boeing 737 MAX 8 planes — the model grounded after two crashes which killed 346 people — has touched down in Alice Springs for storage.

The Civil Aviation Safety Authority (CASA) has given clearance for six Silk Air 737 MAX aircraft to be moved to the plane graveyard at Alice Springs Airport, so they can be stored safely during Singapore's tropical wet season.



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Old 1st Oct 2019, 09:39
  #2789 (permalink)  
 
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MemberBerry;

So much said, can't believe. If the stab trim is not doing what it is supposed to do then shut it down, there are 2 switches for that reasons they did in LionAir the day before the fatal accident. End of story. Any thoughts of what can happen on a stab trim runaway on a FBW aircraft should you need to apply OEB 48 (if still applicable, not flying the small bus for couple of years) if in the mean time your THS endedd up in AND or ANU position?
Now the whole industry is at stake..
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Old 1st Oct 2019, 10:29
  #2790 (permalink)  
 
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The company is fine-tuning a software upgrade for the Max’s flight-control computers in its simulation lab, girding for the evaluation of a final version by line pilots —
I can’t locate the original press statement but this is almost word for word what Boeing said in July.

So what has been happening during the past two months?
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Old 1st Oct 2019, 11:04
  #2791 (permalink)  
SRM
 
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Originally Posted by DHC4 View Post
https://www.abc.net.au/news/2019-10-...rings/11560082


The first of six Boeing 737 MAX 8 planes — the model grounded after two crashes which killed 346 people — has touched down in Alice Springs for storage.

The Civil Aviation Safety Authority (CASA) has given clearance for six Silk Air 737 MAX aircraft to be moved to the plane graveyard at Alice Springs Airport, so they can be stored safely during Singapore's tropical wet season.



I would not call Alice Springs an aircraft graveyard, more like an Aircraft Storage and Maintenance facility with CASA, EASA and FAA Part 145 approvals.
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Old 1st Oct 2019, 13:09
  #2792 (permalink)  
 
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AvWeek

https://aviationweek.com/commercial-...service-return
U.S. Carriers Test New MAX Software; Prep For Service Return
Sep 30, 2019Sean Broderick | Aviation Daily

PLANO, Texas—U.S. pilots who have tested the new Boeing 737 MAX flight-control software have given it positive reviews and some carriers are beginning to finalize step-by-step MAX return-to-service plans, suggesting that Boeing’s notional time line of getting FAA approval by year-end may come to fruition.

American Airlines and Southwest Airlines were among about a dozen carriers that participated in a MAX full-flight simulator session in Miami recently. “For the first time, we were able to get into a full-motion, full-flight MAX simulator,” said Greg Bowen, a Southwest captain and the Southwest Pilots Association (SWAPA) training and standards chair.

Speaking at SWAPA’s International Conference of Pilots Unions, Bowen said the pilots reviewed both the original and modified versions of the MAX’s maneuvering characteristics augmentation system (MCAS) flight-control law software, as well as procedures involving manual trim and other flight-control computer changes.

Bowen said the updated MCAS performs its intended role—automatic horizontal stabilizer nose-down inputs to augment stability in certain high angle-of-attack (AOA) situations—“even better” than the original system. This after Boeing significantly modified the MCAS logic in response to preliminary findings from two fatal MAX accident investigations in which the system, triggered by faulty AOA data inputs, activated when it wasn’t needed and led to fatal dives. “The hazard is being designed out of it,” he said.

The Boeing sessions matched 737 pilots from different airlines as crew pairs. Participants included at least American one pilot with no previous MAX experience, said John DeLeeuw, an American captain and the airline’s senior manager of flight safety. “I think he was pretty happy with the training.”

Bowen emphasized that pilots did not review all of the new training material Boeing is preparing as part of the changes. The FAA and Boeing are still working on some aspects, including at least six non-normal checklists that may require changes either because of the MAX updates or re-thinking of how pilots should tackle certain scenarios, Bowen said.

The FAA will set baseline training, but many airlines are expected to customize it. DeLeeuw said he expects American’s final training package to include two hours of “technical” training plus some instruction on the “social aspect,” such as helping pilots respond to passenger inquiries on the MAX’s safety.

Southwest pilots are reviewing MAX transition training now, Bowen said. The package is Southwest’s “best guess” on what the final package will contain and will be updated once the training is finalized. “It’s a good refresher for our pilots to get back in the MAX mindset,” he said.

The carrier’s return-to-service plan will focus on taking delivery of some 40 aircraft Boeing has built but not delivered, Bowen said. Then, it will work on getting the 34 MAXs it had when the fleet was grounded out of storage. Boeing halted deliveries just after the 385-aircraft fleet was grounded in mid-March, days after the Mar. 10 crash of Ethiopian Airlines Flight 302. It was the second fatal MAX accident in less than five months, following the Oct. 29, 2018, crash of Lion Air Flight 610.

American is preparing to ferry two of its stored MAXs from Roswell, New Mexico to its Tulsa, Oklahoma maintenance base to evaluate their conditions, DeLeeuw said.

“This will give us a chance to have an idea of what we are looking at,” he explained, adding that eliminating service disruptions on the MAX—no matter how minor the reason—will be key to a smooth re-introduction of the fleet. “We want to make sure we get it right.”

Boeing is finalizing the MAX changes and training updates. Its next step is to present a final package to the FAA; the agency is expected to take at least a month to review it. Once the U.S. regulator signs off—FAA officials insist they have no time line—it will issue an airworthiness directive (AD) mandating the changes each MAX needs.

Bowen said he expects Southwest to need at least 30 days from the AD until the first aircraft is ready to return. Southwest calculates each MAX will need an average of 200 man-hours to go from storage to the flight line—only about 2 hrs. of which is installing the new software.
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Old 1st Oct 2019, 14:30
  #2793 (permalink)  
 
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yanrair, #2750,
‘i don't think runaway stab is avoidable on any type?’
Any solution would involve compromise, uncertainty, degree of acceptability, the relative contributions of the man-machine system (in context), and the outcome; as discussed above with Tomaski, #2791.
Training alone is not a solution, a component maybe, providing the consequences of the range of likely human behaviour (judgement) and worst case system malfunction enable recovery.

‘… the aircraft basic trim state. Its the trim moving in such a way as to cause the plane to deviate from its desired path -uncommanded -which tells you its misbehaving.‘
You appear to misjudge the mechanism of stick force feel and flight path perhaps biased by a unique event.
It is normal when maintaining level flight with change in airspeed (maintaining stick position ~) which will change stick force, requiring trim adjustment, a first-order deduction, check speed / trim the aircraft.
Aircraft flight path deviation implies stick movement, but not necessarily a change in trim if power is adjusted and speed maintained; we should not deduce a trim malfunction if speed or power are incorrect for stable fight.
For severe trim malfunctions the crew must be alerted to the condition and action as necessary, then your view of intervention can be applied - minor training task; an if-then drill.
The Max accidents identify the hazards of assuming that crew’s will recognise situations in time to take action, but misjudged against the backdrop of unforeseen / unforeseeable influences on human capability.

Re #2762, ‘I hope we all learned from the AF 447 how not to fly with unreliable IAS. And Turkish Airlines at AMS that an auto-thrust failure should be a non event.‘
Certification authorities have readjusted expectations pitot equipment in rare icing conditions - equipment changed and all aircraft modified.
Re AMS, see full accident report - appendices, which identified a mismatch between what Boeing assumed (sim testing) and more realistic pilot intervention time and height loss as established by the investigation. A familiar theme ?
We cannot expect human intervention to mitigate an inadequate design. Pilot training can mitigate weak designs in certain situations; thus training should focus on understanding the situation and subsequent risk management - awareness, aided by a suitable alerting system (audio, visual, tactile).

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Old 1st Oct 2019, 14:55
  #2794 (permalink)  
 
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We cannot expect human intervention to mitigate an inadequate design.
Which could be read as the aircraft and its automation must be able to cope without assistance from pilots. The beancounters really really like this support for autonomous aircraft.
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Old 1st Oct 2019, 15:10
  #2795 (permalink)  
 
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Ian, it could be read as …
An emerging problem of bias in how the industry, individuals, interpret words; adverse effect of internet - simple, instant answers - acceptance without thought.
‘Inadequate design’ depends on context and certification judgement.
Similarly calls for automation; not more but better, improved thinking, training, and more effective use of what we have.

Bean counters tend to interpret most things to their way of thinking; binary, plus-minus, without context or compromise. A classic human factors problem.
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Old 1st Oct 2019, 15:13
  #2796 (permalink)  
 
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Am I the only one who thinks that ultimately it would have been safer to leave the MCAS off the planes entirely, and just remind the pilots that stalling the aircraft was possible and to monitor their AOA?
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Old 1st Oct 2019, 15:22
  #2797 (permalink)  
 
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Originally Posted by jdawg View Post
You couldn't be more wrong. Or more proud. You blame pilot error and then end by stating we need to identify the cause. Which is it you sound so confused. Let me help. This was not simply pilot error.
have a good night
I did identify the cause: Pilot Error. They failed to control their aircraft when it was possible to do so by using the runaway trim procedures as published. Contributing to that was maybe the fact that they had not been trained to do so (speculation).
You disagree but do not provide facts or opinions as to why. I suspect Political Correctness drives what you write.

The difficulties the crews had in flying the aircraft after the event (one caused by a failed A/A sensor that had not been correctly repaired and the other for a failure not identified) were all made worse because they failed to follow the correct procedures and allowed their aircraft to be uncontrollable and subsequently lost. Those failures included flying above the maximum permitted speed at low altitude, not isolating the trim systems in accordance with the QRH, using the wrong configuration, and mainly not flying the airplane. All pretty basic stuff and if they were newbies with no training I could see it but they were the product of their system and supposedly qualified and capable. Sadly, they were neither.

If we do not acknowledge this (and so many of you refuse to) it matters not what is done to improve the MCAS system because if a pilot does not know how to fly his aircraft it is only a matter of time before another major accident and passenger deaths.

I flew for several airlines that had a reputation (well deserved) for a high accident rate while flying perfectly serviceable airplanes and it was only after the problem was recognized as pilot error and action was taken to rectify that cause that the accident rates dropped. The point is that it is necessary to identify the root cause no matter how unpalatable it might be and to address it with actions that will reduce the risk. Going after Boeing as if their aircraft was the sole cause of the accidents is not going to help. I mentioned the previous accidents in 1996 that were caused by a loss of static information to the flight instruments for example. Neither of these were failures in the aircraft and both could still be safely flown but hundreds of people died.

80 percent of all accidents are pilot error. These accidents are no different. Burying your head in the sand does not help.
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Old 1st Oct 2019, 15:36
  #2798 (permalink)  
 
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Originally Posted by jugofpropwash View Post

Am I the only one who thinks that ultimately it would have been safer to leave the MCAS off the planes entirely, and just remind the pilots that stalling the aircraft was possible and to monitor their AOA?
With hindsight and looking at how light the regulatory hand of the FAA was on this whole process, they may have been able to slide this through the certification process without raising it as much of an issue.

I bet they thought about it!
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Old 1st Oct 2019, 15:49
  #2799 (permalink)  
 
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Pilot Error

boofhead - The myth of human error

https://static1.squarespace.com/stat...ech-Report.pdf

http://www.iploca.com/platform/conte...afetyMyths.pdf

http://www.dcabr.org.br/download/eve...-%20Dedale.pdf

jugofpropwash, #2796
Without MCAS the aircraft could not be certificated.

Like in slide 38 it might be possible to operate, although some parts of the operational flight envelope should be avoided - no Mrs, no stabilising MCAS.




Last edited by safetypee; 1st Oct 2019 at 16:07. Reason: All the wheels came off for Boeing
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Old 1st Oct 2019, 16:29
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IMHO, framing some of the crew’s actions as “pilot error” is not particularly helpful. “Error” implies that the pilots’s actions were inconsistent with the training culture and operational expectations to which they were exposed. We have a sense for what Boeing expected the pilots to do in this situation, but there was obviously a gap between their assumptions and reality. Before we get anywhere near suggesting pilot error, I think the following questions should be asked and answered:
  • How often and when was the last time these pilots practiced a Runaway Stabilizer event in the sim? Was this accomplished at low altitude? How much exposure did they have using the manual trim wheel?
  • How often and when was the last time these pilots practiced an Airspeed Unreliable event in the sim? Was this done during the takeoff phase and did it include an erroneous stick shaker?
  • Were the pilots ever taught to associate a bad AOA input with unreliable airspeed and altitude?
  • Did any of the pilots’ training involve multiple malfunctions, startle, or distraction?
  • What was the automation policy at the pilots’ airline, and did their training and operational culture encourage or discourage hand-flying?
  • Did any of their training or experience prepare them for situations in which there was no obvious written procedure available?
To the degree that the pilots reacted in a manner consistent with how they were trained, I think it is inaccurate to file those actions under the label “pilot error.”
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