User avatar
Revelation
Posts: 20894
Joined: Wed Feb 09, 2005 9:37 pm

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Wed Aug 07, 2019 1:00 pm

Aviation737 wrote:
seahawk wrote:
XRAYretired wrote:
One or two posters likely would call his words hyperbole, click-bait or BS if they were not pro. And, of course any interpretation you make is not allowed unless its on the pro side. You could say they implies MAX was not previously safe (wash my mouth out).

Anyway, the words are easy and hollow since it will 20 or 30 years before they can be confirmed or challenged and the guy is not likely to be around 20 months from now.

For me it is just another form of the "making a safe planes safer" line.

When did he ever say in that statement that the current iteration of the 737 MAX is a safe plane? Didnt they already admit that the MAX had a flaw? I really cant see how that statement that he made was arrogant? To me that statement means that Boeing is working hard on a solution and that they will ensure that the aircraft is safe.

This is exactly why I said the title of the article was BS: people read the title and it left the impression rather than what Boeing's CEO actually said.

People these days live in a state of partial attention, sucking up information from their phones pretty much everywhere they go.

Click bait titles are designed to raise your level of attention and make an impression.

Media get paid by the click and there's no penalty when they make stuff up, so they sex up the title of the story just to get people to click.

Noshow wrote:
Besides the technical and legal ways to get things going again a lot of trust of the airlines, pilots and flying public needs to be regained or should I say redeserved. Keeping quiet will not gain any new positive image for the MAX or whatever it will be called. I'd suggest it's time to come up with more open communications again. This is something the companies top can be blamed for.

The only way to regain confidence is to fix the problems, work with regulators to the point they are confident the problems are fixed, and get the planes flying again.

No "come to Jesus" moment is going to change things, in fact as this thread shows it'll be viewed as a cynical act to pander to customer's sensibilities.

People just aren't in the mood to accept anything Boeing says, the way forward is through actions not words.
Wake up to find out that you are the eyes of the world
The heart has its beaches, its homeland and thoughts of its own
Wake now, discover that you are the song that the morning brings
The heart has its seasons, its evenings and songs of its own
 
ArgentoSystems
Posts: 294
Joined: Sun Mar 24, 2019 12:05 am

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Wed Aug 07, 2019 1:10 pm

By the way, whatever happened to the "Joint Authorities Technical Review" team? They held one meeting in May and were never heard of again.

And FAA... The were giving weekly (albeit lacking substance) updates in May, then took 3 weeks pause in June, and now six weeks and counting without any update at all.
 
planecane
Posts: 990
Joined: Thu Feb 09, 2017 4:58 pm

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Wed Aug 07, 2019 1:27 pm

rheinwaldner wrote:
foxtrotbravo21 wrote:
When the 737 Max hopefully resume flying again in Nov/Dec and after all its modifications and FAA and EASA approvals, it will be one of the safest plane as it would have gone through very thorough and exhautsive tests and scrutiny by the regulators.

Except cutting all the rudder control cables with a single piece of debris from an uncontained engine failure...

Which may also be the same on the NG. Also, it isn't a fact that it is an issue. I would guess if someone filed a freedom of information act request for the certification package it could be confirmed somewhat. Of course that is too much work for a journalist. Much easier to quote a paragraph from an anonymous source.
 
XRAYretired
Posts: 481
Joined: Fri Mar 15, 2019 11:21 am

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Wed Aug 07, 2019 1:36 pm

ArgentoSystems wrote:
By the way, whatever happened to the "Joint Authorities Technical Review" team? They held one meeting in May and were never heard of again.

And FAA... The were giving weekly (albeit lacking substance) updates in May, then took 3 weeks pause in June, and now six weeks and counting without any update at all.

JATR 90 days is up, unless its been extended? I do remember a report of one other meeting that suggested the output would be a separate letter to the FAA from each of the participants independently. No doubt these will be confidential, if it is correct, and likely the FAA would be happy to keep them so.

Ray
 
rheinwaldner
Posts: 1706
Joined: Wed Jan 02, 2008 4:58 pm

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Wed Aug 07, 2019 1:41 pm

planecane wrote:
rheinwaldner wrote:
foxtrotbravo21 wrote:
When the 737 Max hopefully resume flying again in Nov/Dec and after all its modifications and FAA and EASA approvals, it will be one of the safest plane as it would have gone through very thorough and exhautsive tests and scrutiny by the regulators.

Except cutting all the rudder control cables with a single piece of debris from an uncontained engine failure...

Which may also be the same on the NG. Also, it isn't a fact that it is an issue.

What do you think would happen, if say in 2023 a 737 would crash due to this substandard control solution? A grounding until all MAX and NG would be changed? How forgiving would the world be then? Would the drama be smaller or bigger than now?
Many things are difficult, all things are possible!
 
ArgentoSystems
Posts: 294
Joined: Sun Mar 24, 2019 12:05 am

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Wed Aug 07, 2019 1:55 pm

rheinwaldner wrote:
What do you think would happen, if say in 2023 a 737 would crash due to this substandard control solution? A grounding until all MAX and NG would be changed? How forgiving would the world be then? Would the drama be smaller or bigger than now?

In 2023 - likely smaller.
Should it happen in 2020 - it would be a s**tstorm of biblical proportions.
 
blrsea
Posts: 1909
Joined: Fri May 20, 2005 2:22 am

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Wed Aug 07, 2019 2:05 pm

I don't think Boeing will rush through the fix, or that the fix won't be the right one. They know that if another crash occurs, it will be catastrophic to the 737 program and pose serious threat to the company. I don't think anyone in Boeing is thinking that the first thing is to unground the planes rather than ensuring planes are fit to fly. I am sure they have double and triple checked the MCAS fix, and looked into every issue raised by FAA/EASA/other regulatory bodies with a magnifying glass.

They made a costly mistake once, and I don't think they will repeat it, at least not for a few years at least till people forget about this fiasco.
 
User avatar
par13del
Posts: 8651
Joined: Sun Dec 18, 2005 9:14 pm

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Wed Aug 07, 2019 2:13 pm

oOfredOo wrote:
Wired reports the 737-7 flight yesterday as an "engineering flight" gathering data at the request of the FAA.

https://www.wired.com/story/boeing-737- ... and-downs/

Love the article and its unassuming Title, until I read the article I thought the MAX-7 had problems.
Next it is an engineering flight for the FAA, so they speculate on what Boeing is looking for on an FAA mandated flight.
Hopefully, folks here will be able to speculate more than the journalist.
 
planecane
Posts: 990
Joined: Thu Feb 09, 2017 4:58 pm

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Wed Aug 07, 2019 2:43 pm

blrsea wrote:
I don't think Boeing will rush through the fix, or that the fix won't be the right one. They know that if another crash occurs, it will be catastrophic to the 737 program and pose serious threat to the company. I don't think anyone in Boeing is thinking that the first thing is to unground the planes rather than ensuring planes are fit to fly. I am sure they have double and triple checked the MCAS fix, and looked into every issue raised by FAA/EASA/other regulatory bodies with a magnifying glass.

They made a costly mistake once, and I don't think they will repeat it, at least not for a few years at least till people forget about this fiasco.


Great post! Boeing knows that if there is another MAX crash in the next 2 years it will be the end of the 737. Unfortunately, even if the pilot is recorded by liveatc saying he is going to crash into a mountain on purpose and then does it, the MAX design will still get blamed because the headlines will be "Boeing 737MAX Crashes into Mountain." They need to be absolutely sure that no design issue still exists that can lead to a crash. This is why, contrary to the opinions of some posters, I fully expect the MAX to have at least as good of a safety record as the NG going forward.
 
XRAYretired
Posts: 481
Joined: Fri Mar 15, 2019 11:21 am

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Wed Aug 07, 2019 2:44 pm

planecane wrote:
rheinwaldner wrote:
foxtrotbravo21 wrote:
When the 737 Max hopefully resume flying again in Nov/Dec and after all its modifications and FAA and EASA approvals, it will be one of the safest plane as it would have gone through very thorough and exhautsive tests and scrutiny by the regulators.

Except cutting all the rudder control cables with a single piece of debris from an uncontained engine failure...

Which may also be the same on the NG. Also, it isn't a fact that it is an issue. I would guess if someone filed a freedom of information act request for the certification package it could be confirmed somewhat. Of course that is too much work for a journalist. Much easier to quote a paragraph from an anonymous source.

Suspect it is protected by IPR rather than journalistic laziness. IPR is otherwise OK but not on this occasion? Journalists are probably responsible for a significant proportion of FOIs and without them we'd know nowt at all.

Ray
 
XRAYretired
Posts: 481
Joined: Fri Mar 15, 2019 11:21 am

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Wed Aug 07, 2019 2:58 pm

blrsea wrote:
I don't think Boeing will rush through the fix, or that the fix won't be the right one. They know that if another crash occurs, it will be catastrophic to the 737 program and pose serious threat to the company. I don't think anyone in Boeing is thinking that the first thing is to unground the planes rather than ensuring planes are fit to fly. I am sure they have double and triple checked the MCAS fix, and looked into every issue raised by FAA/EASA/other regulatory bodies with a magnifying glass.

They made a costly mistake once, and I don't think they will repeat it, at least not for a few years at least till people forget about this fiasco.

Its a shame Boeing it appears were still trying to avoid fixing potentially catastrophic outcome from the bit flip testing right up until June this year. Rather spoils the impression of magnifying glass pursuit of perfection. Fortunately, they are not being allowed to dismiss things anymore.

Ray
 
Spetsnaz55
Posts: 72
Joined: Wed Feb 20, 2019 2:38 am

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Wed Aug 07, 2019 3:02 pm

XRAYretired wrote:
blrsea wrote:
I don't think Boeing will rush through the fix, or that the fix won't be the right one. They know that if another crash occurs, it will be catastrophic to the 737 program and pose serious threat to the company. I don't think anyone in Boeing is thinking that the first thing is to unground the planes rather than ensuring planes are fit to fly. I am sure they have double and triple checked the MCAS fix, and looked into every issue raised by FAA/EASA/other regulatory bodies with a magnifying glass.

They made a costly mistake once, and I don't think they will repeat it, at least not for a few years at least till people forget about this fiasco.

Its a shame Boeing it appears were still trying to avoid fixing potentially catastrophic outcome from the bit flip testing right up until June this year. Rather spoils the impression of magnifying glass pursuit of perfection. Fortunately, they are not being allowed to dismiss things anymore.

Ray


Evidence of Boeing knowing about the bit flip problem before June And them avoiding trying to fix it up until June?
Have never seen anything like that before
 
Noshow
Posts: 936
Joined: Wed Jun 15, 2016 3:20 pm

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Wed Aug 07, 2019 3:15 pm

Mr. Muilenburg said this morning he expects some MAX return to service in early Q4. What software fix can be done until then? Handover of proposal to FAA needed by september for this schedule.
 
ArgentoSystems
Posts: 294
Joined: Sun Mar 24, 2019 12:05 am

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Wed Aug 07, 2019 3:36 pm

Noshow wrote:
Mr. Muilenburg said this morning he expects some MAX return to service in early Q4. What software fix can be done until then? Handover of proposal to FAA needed by september for this schedule.


Why do they keep saying "Early Q4" instead of October? November is already mid Q4 and September is Q3. That is a ridiculous way to specify dates.
Realistically, if they are to submit their certification package in Sep, how do they expect FAA to complete certification in one month? Well ok, two months, if they somehow finish their update Sep 1st.
 
XRAYretired
Posts: 481
Joined: Fri Mar 15, 2019 11:21 am

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Wed Aug 07, 2019 3:55 pm

Spetsnaz55 wrote:
XRAYretired wrote:
blrsea wrote:
I don't think Boeing will rush through the fix, or that the fix won't be the right one. They know that if another crash occurs, it will be catastrophic to the 737 program and pose serious threat to the company. I don't think anyone in Boeing is thinking that the first thing is to unground the planes rather than ensuring planes are fit to fly. I am sure they have double and triple checked the MCAS fix, and looked into every issue raised by FAA/EASA/other regulatory bodies with a magnifying glass.

They made a costly mistake once, and I don't think they will repeat it, at least not for a few years at least till people forget about this fiasco.

Its a shame Boeing it appears were still trying to avoid fixing potentially catastrophic outcome from the bit flip testing right up until June this year. Rather spoils the impression of magnifying glass pursuit of perfection. Fortunately, they are not being allowed to dismiss things anymore.

Ray


Evidence of Boeing knowing about the bit flip problem before June And them avoiding trying to fix it up until June?
Have never seen anything like that before

Found in June according to reports.
https://theaircurrent.com/aviation-safe ... re-glitch/
Discussed in #Q2 thread. You must have missed it.

Ray
 
ArgentoSystems
Posts: 294
Joined: Sun Mar 24, 2019 12:05 am

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Wed Aug 07, 2019 3:58 pm

Actually this is what he said today:
Dennis Muilenburg said Boeing planned to submit its certification package to the US Federal Aviation Administration around September, with expected approval around a month later.


So not in September anymore, but "around September". Surely that does not mean August. Shall we say Oct-ember? And certification "around month later"? Hm... Even FAA is not brave enough to make any promises on the time-frames.
 
DenverTed
Posts: 242
Joined: Wed Mar 27, 2019 11:12 pm

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Wed Aug 07, 2019 4:03 pm

jollo wrote:
Sorry if this had been already discussed (out of the loop for a while and the MAX threads are too prolific to really catch up), but I can’t find whether the real (or alleged) reason for Boeing to change the function of the STAB TRIM CUTOUT switches from NG to MAX has been explained or not. A recap on this issue for clarification:

NG has two distinct STAB TRIM CUT OUT switches because it has - unlike previous 737 models - a single horizontal stab actuator (electric motor) with two command inputs: one from the “manual” yoke trim switches and one from the FCC. So one cut out switch, labelled AUTO PILOT, allows pilots to cut out all FCC inputs (including A/P and STS) while still retaining manual control over the electric stab trim actuator, and the other, labelled MAIN ELECT, completely cuts off the actuator and therefore also disables yoke trim switch commands.

Notes:
* The flight crew is directed to use cut out switches only within the “Runaway Stabilizer” NNC, and only by acting on both switches at once;
* The ability to cut out only FCC commands while still retaining manual control over the electric stab trim actuator could possibly have helped pilots to cope with the fatal “AND out-of-trim + high speed” situation late in the ET accident (if they had been driving an NG - of course, in an NG they would not have experienced the severe AND out-of-trim runaway in the first place, so this is speculation).

MAX still has two STAB TRIM CUT OUT switches, re-labeled PRI and B/U (conceivably meant as “PRImary” and “Back/Up”), but their function was altered so that both switches directly disable the actuator; therefore setting either switch to CUT OUT disables both FCC and yoke trim switch commands, leaving only the manual trim wheel for horizontal stab control.

However, certification documentation submitted to FAA omits to mention the function change and only describes a labeling change; the (in)famous iPad 1-hour training also only mentions the change as relabeling and the FCOM doesn’t mention the change at all (it still directs pilots to move both switches at once).

Now, let’s please avoid if possible a discussion about the moral and legal liabilities of hiding changes in the certification process, or about the MCAS 1.0 implementation being or not the result of a series of appalling, but good-faith engineering and process failures.

My question is: has anyone found a credible reason for Boeing to have implemented, and then hidden, a functional change in an area where, arguably, it would have been easier and better to “leave well enough alone”?

Thanks and cheers

What good are two switches on the NG if the procedure is to flip both of them? What was the procedure on the classic? Having two switches doesn't seem logical if there is no procedure that calls for using them individually.
 
DenverTed
Posts: 242
Joined: Wed Mar 27, 2019 11:12 pm

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Wed Aug 07, 2019 4:10 pm

So when I get on an NG, if they're doing their job, the FAA can guarantee me that the trim wheel is not a problem, the rudder cables are up to regulation, and the bit flip is not an issue on the mach trim or speed trim systems, in spite of the fact that the NG is single computer and vulnerable to single computer bit flip failure?
 
planecane
Posts: 990
Joined: Thu Feb 09, 2017 4:58 pm

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Wed Aug 07, 2019 4:39 pm

DenverTed wrote:
What good are two switches on the NG if the procedure is to flip both of them? What was the procedure on the classic? Having two switches doesn't seem logical if there is no procedure that calls for using them individually.


This is from a QRH I found and the person that posted the file said it is the 737-300/400/500. The document itself only says "737" but it is slightly different than the NG QRH I have seen.

Condition: Continuing rotation of the stabilizer trim wheel in a manner not appropriate for flight conditions.

CONTROL COLUMN..............................…HOLD FIRMLY

AUTOPILOT (if engaged)............................DISENGAGE
Do not re-engage the autopilot.
Control airplane pitch attitude manually with control
column and main electric trim as required.

If runaway continues:

STABILIZER TRIM CUTOUT
SWITCHES..............................................CUTOUT

If runaway continues:

STABILIZER TRIM WHEEL.............GRASP & HOLD



So, assuming this is for the classic as the poster stated, the procedure was/is to use both switches. This jibes with Muilenburg's statement that the procedure was always to cut out both switches.
 
planecane
Posts: 990
Joined: Thu Feb 09, 2017 4:58 pm

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Wed Aug 07, 2019 4:42 pm

DenverTed wrote:
So when I get on an NG, if they're doing their job, the FAA can guarantee me that the trim wheel is not a problem, the rudder cables are up to regulation, and the bit flip is not an issue on the mach trim or speed trim systems, in spite of the fact that the NG is single computer and vulnerable to single computer bit flip failure?


No, they can't guarantee that on an NG. And yet, the NG has an equivalent safety record to the far more technically advanced A320.

Regulation and certification are to try and reach a high level of safety. Nothing will guarantee that no plane can ever possibly crash. You'd need so much structural and system redundancy that the aircraft would be uneconomically heavy and too costly to build without airfare being 10 times what it is now.
 
therealsuperuse
Posts: 2
Joined: Wed Aug 07, 2019 3:16 am

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Wed Aug 07, 2019 5:15 pm

bombayduck wrote:
Probably 737-800's as the MAX is still grounded. Also I think that Alaskan do not have any B38M aircraft.


Thanks bombayduck and whiteguy. I noticed a couple minutes later as I was entering one of the pseudo MAXes that turned out to be an NG. From afar, the wingtip design looked deceptively similar.
 
Spetsnaz55
Posts: 72
Joined: Wed Feb 20, 2019 2:38 am

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Wed Aug 07, 2019 5:32 pm

XRAYretired wrote:
Spetsnaz55 wrote:
XRAYretired wrote:
Its a shame Boeing it appears were still trying to avoid fixing potentially catastrophic outcome from the bit flip testing right up until June this year. Rather spoils the impression of magnifying glass pursuit of perfection. Fortunately, they are not being allowed to dismiss things anymore.

Ray


Evidence of Boeing knowing about the bit flip problem before June And them avoiding trying to fix it up until June?
Have never seen anything like that before

Found in June according to reports.
https://theaircurrent.com/aviation-safe ... re-glitch/
Discussed in #Q2 thread. You must have missed it.

Ray


Yes exactly found in june when the FAA was doing testing and found it. So boeing only knew about it in june and the bit flip fix started after they found out.. now re read your original statement? Which part is a shame again?
 
airnorth
Posts: 341
Joined: Thu Jun 09, 2011 7:30 am

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Wed Aug 07, 2019 5:58 pm

XRAYretired wrote:
planecane wrote:
rheinwaldner wrote:
Except cutting all the rudder control cables with a single piece of debris from an uncontained engine failure...

Which may also be the same on the NG. Also, it isn't a fact that it is an issue. I would guess if someone filed a freedom of information act request for the certification package it could be confirmed somewhat. Of course that is too much work for a journalist. Much easier to quote a paragraph from an anonymous source.

Suspect it is protected by IPR rather than journalistic laziness. IPR is otherwise OK but not on this occasion? Journalists are probably responsible for a significant proportion of FOIs and without them we'd know nowt at all.

Ray

I work in a Company full of acronyms, but am not familiar with IPR, and FOI, can anyone shed light on this? I know it will be a face palm moment afterwards but it will help me follow this thread!

TIA
airnorth
 
XRAYretired
Posts: 481
Joined: Fri Mar 15, 2019 11:21 am

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Wed Aug 07, 2019 6:11 pm

airnorth wrote:
XRAYretired wrote:
planecane wrote:
Which may also be the same on the NG. Also, it isn't a fact that it is an issue. I would guess if someone filed a freedom of information act request for the certification package it could be confirmed somewhat. Of course that is too much work for a journalist. Much easier to quote a paragraph from an anonymous source.

Suspect it is protected by IPR rather than journalistic laziness. IPR is otherwise OK but not on this occasion? Journalists are probably responsible for a significant proportion of FOIs and without them we'd know nowt at all.

Ray

I work in a Company full of acronyms, but am not familiar with IPR, and FOI, can anyone shed light on this? I know it will be a face palm moment afterwards but it will help me follow this thread!

TIA
airnorth

Apologies. Intellectual Property Rights and Fredom Of Information (request).
 
planecane
Posts: 990
Joined: Thu Feb 09, 2017 4:58 pm

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Wed Aug 07, 2019 6:12 pm

airnorth wrote:
XRAYretired wrote:
planecane wrote:
Which may also be the same on the NG. Also, it isn't a fact that it is an issue. I would guess if someone filed a freedom of information act request for the certification package it could be confirmed somewhat. Of course that is too much work for a journalist. Much easier to quote a paragraph from an anonymous source.

Suspect it is protected by IPR rather than journalistic laziness. IPR is otherwise OK but not on this occasion? Journalists are probably responsible for a significant proportion of FOIs and without them we'd know nowt at all.

Ray

I work in a Company full of acronyms, but am not familiar with IPR, and FOI, can anyone shed light on this? I know it will be a face palm moment afterwards but it will help me follow this thread!

TIA
airnorth


It just hit me now, IPR=intellectual property rights and FOI=freedom of information
 
Spetsnaz55
Posts: 72
Joined: Wed Feb 20, 2019 2:38 am

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Wed Aug 07, 2019 7:08 pm

XRAYretired wrote:
Spetsnaz55 wrote:
XRAYretired wrote:
Found in June according to reports.
https://theaircurrent.com/aviation-safe ... re-glitch/
Discussed in #Q2 thread. You must have missed it.

Ray


Yes exactly found in june when the FAA was doing testing and found it. So boeing only knew about it in june and the bit flip fix started after they found out.. now re read your original statement? Which part is a shame again?

Read it how you like. Boeing were apparently still trying to avoid fixing a potential catastrophic outcome in June. Miss-interpretation of my words does not change that.

Not clever just sad.

Ray


Dude I dont get it. Show me an article of Boeing finding out about the bit flip and trying to avoid fixing it. Where did you see that? Give me an article or something. All I have ever seen is the FAA finding out about the bit flip and then we hear that Boeing is gonna fix it right away. are you saying Boeing knew about the bit flip before the FAA found it? Or are you just saying random crap to make Boeing look shameful?
 
MrBretz
Posts: 349
Joined: Tue Jun 14, 2016 9:13 pm

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Wed Aug 07, 2019 7:12 pm

XRAYretired wrote:
MrBretz wrote:
DenverTed wrote:
Is the cosmic ray flip flop test in the FAA regulations?


No, but the surprise UFO appearance is.

If it covered specifically in FAR/JAR, I don’t know, but it is a relevant design requirement.

‘Bit Flipping’ or Single/Multiple Event Upset/Latching is an observable phenomenon and is the result of the impact of high energy neutrons released by the collision of cosmic radiation with matter in the atmosphere. It is only ‘esoteric’ in that few people understand it, or rather, take the trouble to research it. The rate at which impacts occur are based on observational science not some guess-work. US cant be isolationist on this one (or cosmic ray deniers!).

Without being privy to the certification teams approach to arrive at 5 bit flips, I would suspect this is the worst case number that can be predicted in a maximum flight leg duration and profile from the science, with a probability of <1E-12. Not just remote but extremely remote and this is number required to be achieved for catastrophic event likelihood. Hazardous outcomes would also need to considered.

So, if it can be demonstrated that the worst case failure is not catastrophic/Hazardous, then all is well. The requirement is met.

In order to test this hypothesis, bearing in mind that the impacts are entirely random in location, you can either spend a few years testing very possible combination of 5 bits (since every combination is as probable as every other one), or you can deduce by analysis what the worst case combinations of 5 bits are, in terms of what the potential combined effects are, and test those. This is what they would seem to have done and a combination was demonstrated to be potentially catastrophic in outcome and therefore the requirement is not met.

Boeing appear to have argued that this should not be categorised catastrophic outcome, rather major, on the basis that the pilot can catch it. They were proved and instructed otherwise. This would seem similar to the Flap System problem, we have little information on, but it seems Boeing had to be instructed it was catastrophic. Strangely enough, also seems a corollary of MCAS where at least some functioning engineers declared outcomes as major and have been proven catastrophically wrong. There might be an unchanging pattern here, but I’d be blowed if I can see it.

Ray


Ray, please send me a link so I can get educated. This would never happen on the military flight computers I worked on since the computers were “hardened”. I have always assumed commercial machines in airplanes had some type of protection, like a simple box around the processor.

I know we had occasional noisy inputs. But we filtered them to get rid of that random spike.

Looking forward to your link.
 
ArgentoSystems
Posts: 294
Joined: Sun Mar 24, 2019 12:05 am

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Wed Aug 07, 2019 7:22 pm

MrBretz wrote:
Ray, please send me a link so I can get educated. This would never happen on the military flight computers I worked on since the computers were “hardened”. I have always assumed commercial machines in airplanes had some type of protection, like a simple box around the processor.

I know we had occasional noisy inputs. But we filtered them to get rid of that random spike.

Looking forward to your link.

This cosmic ray thing is some kind of bogeyman to distract from the real unknown issues.

Let's just accept that we do not have hard data on the nature of the problem from June. There were two rumors on that, both originating from anon sources, and I can't really pick which one of them is more bizarre than the other.
 
XRAYretired
Posts: 481
Joined: Fri Mar 15, 2019 11:21 am

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Wed Aug 07, 2019 7:58 pm

MrBretz wrote:
XRAYretired wrote:
MrBretz wrote:

No, but the surprise UFO appearance is.

If it covered specifically in FAR/JAR, I don’t know, but it is a relevant design requirement.

‘Bit Flipping’ or Single/Multiple Event Upset/Latching is an observable phenomenon and is the result of the impact of high energy neutrons released by the collision of cosmic radiation with matter in the atmosphere. It is only ‘esoteric’ in that few people understand it, or rather, take the trouble to research it. The rate at which impacts occur are based on observational science not some guess-work. US cant be isolationist on this one (or cosmic ray deniers!).

Without being privy to the certification teams approach to arrive at 5 bit flips, I would suspect this is the worst case number that can be predicted in a maximum flight leg duration and profile from the science, with a probability of <1E-12. Not just remote but extremely remote and this is number required to be achieved for catastrophic event likelihood. Hazardous outcomes would also need to considered.

So, if it can be demonstrated that the worst case failure is not catastrophic/Hazardous, then all is well. The requirement is met.

In order to test this hypothesis, bearing in mind that the impacts are entirely random in location, you can either spend a few years testing very possible combination of 5 bits (since every combination is as probable as every other one), or you can deduce by analysis what the worst case combinations of 5 bits are, in terms of what the potential combined effects are, and test those. This is what they would seem to have done and a combination was demonstrated to be potentially catastrophic in outcome and therefore the requirement is not met.

Boeing appear to have argued that this should not be categorised catastrophic outcome, rather major, on the basis that the pilot can catch it. They were proved and instructed otherwise. This would seem similar to the Flap System problem, we have little information on, but it seems Boeing had to be instructed it was catastrophic. Strangely enough, also seems a corollary of MCAS where at least some functioning engineers declared outcomes as major and have been proven catastrophically wrong. There might be an unchanging pattern here, but I’d be blowed if I can see it.

Ray


Ray, please send me a link so I can get educated. This would never happen on the military flight computers I worked on since the computers were “hardened”. I have always assumed commercial machines in airplanes had some type of protection, like a simple box around the processor.

I know we had occasional noisy inputs. But we filtered them to get rid of that random spike.

Looking forward to your link.


Delighted. I would expect most civil avionics these days are demonstrated compliant by component selection, defensive design and analysis rather than testing.

Publicly available. I like the NASA thing because its bullet points and does not try to confuse too much. The EASA doc is relatively short and readable.

https://spacemath.gsfc.nasa.gov/weekly/3Page6.pdf
https://www.easa.europa.eu/sites/defaul ... e%2001.pdf

Ray
 
RickNRoll
Posts: 1707
Joined: Fri Jan 06, 2012 9:30 am

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Wed Aug 07, 2019 8:01 pm

planecane wrote:
rheinwaldner wrote:
foxtrotbravo21 wrote:
When the 737 Max hopefully resume flying again in Nov/Dec and after all its modifications and FAA and EASA approvals, it will be one of the safest plane as it would have gone through very thorough and exhautsive tests and scrutiny by the regulators.

Except cutting all the rudder control cables with a single piece of debris from an uncontained engine failure...

Which may also be the same on the NG. Also, it isn't a fact that it is an issue. I would guess if someone filed a freedom of information act request for the certification package it could be confirmed somewhat. Of course that is too much work for a journalist. Much easier to quote a paragraph from an anonymous source.


The engine location on the NG means there is more metal in between the engine blades and the control cables (The wing roots, IIRC) which gives them some 'armour' protection.
 
RickNRoll
Posts: 1707
Joined: Fri Jan 06, 2012 9:30 am

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Wed Aug 07, 2019 8:05 pm

DenverTed wrote:
So when I get on an NG, if they're doing their job, the FAA can guarantee me that the trim wheel is not a problem, the rudder cables are up to regulation, and the bit flip is not an issue on the mach trim or speed trim systems, in spite of the fact that the NG is single computer and vulnerable to single computer bit flip failure?

The trim wheels were already compromised by entry of the NG. The Display Screens were larger, which made a pinch point at the place where you place your hand to turn it manually. So they made the wheels smaller, which meant they were harder to turn. They also had to put dampers on the mechanism to stop backlash, which made the wheels even harder to turn.
 
User avatar
flyingturtle
Posts: 5613
Joined: Mon Oct 31, 2011 1:39 pm

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Wed Aug 07, 2019 8:33 pm

I bought the SPIEGEL, mainly because of the article on Boeing and the 737 MAX. For us a.nutters, it doesn't contain really noteworthy things. To laypeople, though, I recommend it because it's a comprehensive re-telling of all the events (competition between Boeing and Airbus, changing corporate culture at Boeing, the story of the 737 and its missing replacement, explanation of MCAS, how it malfunctioned...). It's a solid piece of reporting, they sent teams to Ethipia, the US, to Indonesia...

A spokesperson for Boeing was interviewed, but he left the table after just five minutes. He refused to answer any hard questions...
Reading accident reports is what calms me down
 
RickNRoll
Posts: 1707
Joined: Fri Jan 06, 2012 9:30 am

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Wed Aug 07, 2019 8:35 pm

ArgentoSystems wrote:
By the way, whatever happened to the "Joint Authorities Technical Review" team? They held one meeting in May and were never heard of again.

And FAA... The were giving weekly (albeit lacking substance) updates in May, then took 3 weeks pause in June, and now six weeks and counting without any update at all.


I would suggest they are waiting for something to review. That won't be available for some months.
 
jollo
Posts: 349
Joined: Mon Aug 08, 2011 7:24 pm

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Wed Aug 07, 2019 8:44 pm

DenverTed wrote:
jollo wrote:
Sorry if this had been already discussed (out of the loop for a while and the MAX threads are too prolific to really catch up), but I can’t find whether the real (or alleged) reason for Boeing to change the function of the STAB TRIM CUTOUT switches from NG to MAX has been explained or not.
[...]
My question is: has anyone found a credible reason for Boeing to have implemented, and then hidden, a functional change in an area where, arguably, it would have been easier and better to “leave well enough alone”?

Thanks and cheers

What good are two switches on the NG if the procedure is to flip both of them? What was the procedure on the classic? Having two switches doesn't seem logical if there is no procedure that calls for using them individually.


* AFAIK the Classic (and the 727, and 707) had two cutout switches because it had two separate electric actuators for A/P inputs and “manual” electric trim inputs (through yoke switches)
* the NG has a single stab trim actuator, but retained (probably for grandfathering purposes) separate cutout switches for A/P (FCC, really) and “manual” electric trim inputs; therefore, the function of the cutout switches was unchanged
* NCCs have to be concise; the “runaway stabilizer” NCC was probably considered, since Classinc days, to be long enough as it is and that adding another step for sequential activation of the cutout switches would have no material effect on safety (after all, A/P disengage is one of the first items in the checklist)

However, none of this explains why Boeing felt the need to change the function of the cutout switches on the MAX, especially considering how they carefully maintained function unchanged between the Classic and the NG.
 
smartplane
Posts: 1024
Joined: Fri Aug 03, 2018 9:23 pm

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Wed Aug 07, 2019 8:45 pm

ArgentoSystems wrote:
By the way, whatever happened to the "Joint Authorities Technical Review" team? They held one meeting in May and were never heard of again.

And FAA... The were giving weekly (albeit lacking substance) updates in May, then took 3 weeks pause in June, and now six weeks and counting without any update at all.

The 'outsiders' (EASA, TCCA and CAAC) have been meeting in the UK virtually every month, with no FAA reps in attendance.

Debate is focused on what must be rectified before the aircraft grounding ceases (and definition of 'rectified'), versus what will be subject to AD's.

Absence of FAA (and others) updates is because Boeing has waived the big stick in respect to material notifications, listing requirements, and consequences, which shuts down information, the basis for continued discussions and analysis, a key goal of the PR crisis team. Only need to look at this thread to see how successful it's been, and how boredom leads to lower levels of participation.
 
DenverTed
Posts: 242
Joined: Wed Mar 27, 2019 11:12 pm

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Wed Aug 07, 2019 8:52 pm

jollo wrote:
DenverTed wrote:
jollo wrote:
Sorry if this had been already discussed (out of the loop for a while and the MAX threads are too prolific to really catch up), but I can’t find whether the real (or alleged) reason for Boeing to change the function of the STAB TRIM CUTOUT switches from NG to MAX has been explained or not.
[...]
My question is: has anyone found a credible reason for Boeing to have implemented, and then hidden, a functional change in an area where, arguably, it would have been easier and better to “leave well enough alone”?

Thanks and cheers

What good are two switches on the NG if the procedure is to flip both of them? What was the procedure on the classic? Having two switches doesn't seem logical if there is no procedure that calls for using them individually.


* AFAIK the Classic (and the 727, and 707) had two cutout switches because it had two separate electric actuators for A/P inputs and “manual” electric trim inputs (through yoke switches)
* the NG has a single stab trim actuator, but retained (probably for grandfathering purposes) separate cutout switches for A/P (FCC, really) and “manual” electric trim inputs; therefore, the function of the cutout switches was unchanged
* NCCs have to be concise; the “runaway stabilizer” NCC was probably considered, since Classinc days, to be long enough as it is and that adding another step for sequential activation of the cutout switches would have no material effect on safety (after all, A/P disengage is one of the first items in the checklist)

However, none of this explains why Boeing felt the need to change the function of the cutout switches on the MAX, especially considering how they carefully maintained function unchanged between the Classic and the NG.

I wonder if the old ones had two separate linear actuators(screws), or two electric motors on the same linear actuator?
 
ArgentoSystems
Posts: 294
Joined: Sun Mar 24, 2019 12:05 am

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Wed Aug 07, 2019 8:57 pm

smartplane wrote:
The 'outsiders' (EASA, TCCA and CAAC) have been meeting in the UK virtually every month, with no FAA reps in attendance.

Debate is focused on what must be rectified before the aircraft grounding ceases (and definition of 'rectified'), versus what will be subject to AD's.

Thank you. Where do you get this information? Any more details about what must be rectified etc? I would appreciate any links.
 
planecane
Posts: 990
Joined: Thu Feb 09, 2017 4:58 pm

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Wed Aug 07, 2019 9:04 pm

RickNRoll wrote:
planecane wrote:
rheinwaldner wrote:
Except cutting all the rudder control cables with a single piece of debris from an uncontained engine failure...

Which may also be the same on the NG. Also, it isn't a fact that it is an issue. I would guess if someone filed a freedom of information act request for the certification package it could be confirmed somewhat. Of course that is too much work for a journalist. Much easier to quote a paragraph from an anonymous source.


The engine location on the NG means there is more metal in between the engine blades and the control cables (The wing roots, IIRC) which gives them some 'armour' protection.


With no exact measurement, as best I can tell from side-on photos, the MAX engines are 1 frame farther forward. I'd guess this is under 2' based on some seats having 2 windows if the pitch is great enough.

Is that enough distance for the turbine disks to align with more "armor?" I don't know, I'm putting the question out there.
 
planecane
Posts: 990
Joined: Thu Feb 09, 2017 4:58 pm

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Thu Aug 08, 2019 12:43 am

DenverTed wrote:
jollo wrote:
DenverTed wrote:
What good are two switches on the NG if the procedure is to flip both of them? What was the procedure on the classic? Having two switches doesn't seem logical if there is no procedure that calls for using them individually.


* AFAIK the Classic (and the 727, and 707) had two cutout switches because it had two separate electric actuators for A/P inputs and “manual” electric trim inputs (through yoke switches)
* the NG has a single stab trim actuator, but retained (probably for grandfathering purposes) separate cutout switches for A/P (FCC, really) and “manual” electric trim inputs; therefore, the function of the cutout switches was unchanged
* NCCs have to be concise; the “runaway stabilizer” NCC was probably considered, since Classinc days, to be long enough as it is and that adding another step for sequential activation of the cutout switches would have no material effect on safety (after all, A/P disengage is one of the first items in the checklist)

However, none of this explains why Boeing felt the need to change the function of the cutout switches on the MAX, especially considering how they carefully maintained function unchanged between the Classic and the NG.

I wonder if the old ones had two separate linear actuators(screws), or two electric motors on the same linear actuator?


That's a good question. The other question is why, if they had 2 motors, would they make one for autopilot and the other for manual instead of making them redundant for both in case of a failure.

Also interesting is that, apparently on the classic, there were at least 4 runaway stabilizer events. This is from an FCOM dated 1995:


Background Information

Four operators have reported instances of excessive stabilizer trim system coasting (stabilizer trim wheel continues to rotate) after the control wheel stabilizer trim switches have been activated and released. The reports indicate that when the pilot released the trim switches. the stabilizer trim wheel coasted up to 40 turns (four units of trim). In sonic instances the trim wheel stopped moving in the commanded direction and then rotated lip to 40 turns in the opposite direction.

The stabilizer trim main electric motor turns in only one direction. It drives the stabilizer trim actuator through two electro-magnetic clutches. One clutch is engaged for nose-up trim and the other is engaged for nose-down trim. Boeing examination of a suspect clutch showed that the reported coasting and/or reverse coasting of the stabilizer manual trim wheel was due to intermittent jamming of a clutch disc in one of the clutch assemblies. As a result, the electric motor will remain mechanically connected to the stabilizer trim mechanical actuator gear system after the control wheel stabilizer trim switches have been released.
With flaps down. the electric motor can continue to rotate up to 40 additional rums of the manual trim wheel after electrical power has been removed. With flaps up. manual trim wheel coasting is not significant because of the reduced trim motor speed. The autopilot trim system. which uses a motor that turns in either direction and drives the stabilizer trim through a single clutch, does not exhibit this problem.
Boeing Service Bulletin 737-27A1 191. dated October 13, 1994, and revision dated November 3. 1994. provide instructions to replace the stabilizer trim electric actuator on the stabilizer trim control system.

Recommended Operating Procedures

The current Runaway Stabilizer procedure will effectively inhibit and limit an out of trim condition. Normal pilot reaction to a runaway stabilizer of opposing the runaway with main electric trim in addition to control column force will initially resolve a runaway. The Runaway Stabilizer Checklist recall action, "STABILIZER TRIM CUTOUT SWITCHES....CUTOUT” will isolate the malfunction if the runaway was caused by the main electric trim or autopilot trim systems. The stabilizer trim cutout switches only remove electrical power to the electric motors.

If the trim wheel continues to rotate after this action has been taken. the recall action "STBILIZER TRIM WHEEL.... GRASP AND HOLD” will prevent further runaway or coasting. If the electric motor remains mechanically connected to the stabilizer trim mechanical actuator gear system because of a clutch malfunction, actuating the stabilizer trim cutout switches to cutout will not immediately stop the trim wheel rotation. Grasping the trim wheel will stop the rotation more quickly than allowing the trim wheel to coast to a stop, keeping the airplane more in trim.
In accordance with the procedure, trim the stabilizer manually for the remainder of the flight.


I hate to mention this because I really don't want to start the circular argument again but I did notice the line which says:

Normal pilot reaction to a runaway stabilizer of opposing the runaway with main electric trim in addition to control column force will initially resolve a runaway.


This would seem to indicate that the assumption of how a pilot of a MAX would respond to an MCAS was not some crazy incompetent fantasy. This statement goes back to 1995. It also references the " Runaway Stabilizer Checklist recall action, "STABILIZER TRIM CUTOUT SWITCHES....CUTOUT”"
 
jetmatt777
Posts: 3845
Joined: Sun Jun 26, 2005 2:16 am

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Thu Aug 08, 2019 1:08 am

Runaway implies the wheel is constantly turning, “running away”. MCAS is incremental therefore understandable to not immediately conclude that the trim is the problem, especially when (before now) MCAS wasn’t really even explained to the pilots. Why was the plane pitching over? Their first thought may have been the autopilot, so their eyes may have been on the MCP. I think it’s easy on the ground to say they should have just went to the cutout switches first and foremost. I think with a little more air time and training (on MCAS) they would have gotten to that point. But if the trim isn’t running away from you, why would you make that your first remedy?
Lighten up while you still can, don't even try to understand, just find a place to make your stand and take it easy
 
planecane
Posts: 990
Joined: Thu Feb 09, 2017 4:58 pm

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Thu Aug 08, 2019 1:44 am

jetmatt777 wrote:
Runaway implies the wheel is constantly turning, “running away”. MCAS is incremental therefore understandable to not immediately conclude that the trim is the problem, especially when (before now) MCAS wasn’t really even explained to the pilots. Why was the plane pitching over? Their first thought may have been the autopilot, so their eyes may have been on the MCP. I think it’s easy on the ground to say they should have just went to the cutout switches first and foremost. I think with a little more air time and training (on MCAS) they would have gotten to that point. But if the trim isn’t running away from you, why would you make that your first remedy?


First, I said I didn't want to start this circular argument again. My point was that the ASSUMPTION that was made about how pilots would react was not crazy.

However, since you went there, THE MCAS FAILURES WERE NOT INCREMENTAL. If you look at the plots in both crash reports, the initial event was a complete MCAS cycle.

For a failure mode that is supposed to be critical and reacted to quickly, how is 10 seconds of continuous uncommanded nose down trim not considered a runaway?

Of all the arguments, this one makes absolutely no sense to me.

For the 1000th time, I am not "blaming the pilots." It was either lack of training or the fact that there were a bunch of other issues happening concurrently with the runaway stabilizer that caused the crews not to respond properly.
 
MrBretz
Posts: 349
Joined: Tue Jun 14, 2016 9:13 pm

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Thu Aug 08, 2019 6:51 am

XRAYretired wrote:
MrBretz wrote:
XRAYretired wrote:
If it covered specifically in FAR/JAR, I don’t know, but it is a relevant design requirement.

‘Bit Flipping’ or Single/Multiple Event Upset/Latching is an observable phenomenon and is the result of the impact of high energy neutrons released by the collision of cosmic radiation with matter in the atmosphere. It is only ‘esoteric’ in that few people understand it, or rather, take the trouble to research it. The rate at which impacts occur are based on observational science not some guess-work. US cant be isolationist on this one (or cosmic ray deniers!).

Without being privy to the certification teams approach to arrive at 5 bit flips, I would suspect this is the worst case number that can be predicted in a maximum flight leg duration and profile from the science, with a probability of <1E-12. Not just remote but extremely remote and this is number required to be achieved for catastrophic event likelihood. Hazardous outcomes would also need to considered.

So, if it can be demonstrated that the worst case failure is not catastrophic/Hazardous, then all is well. The requirement is met.

In order to test this hypothesis, bearing in mind that the impacts are entirely random in location, you can either spend a few years testing very possible combination of 5 bits (since every combination is as probable as every other one), or you can deduce by analysis what the worst case combinations of 5 bits are, in terms of what the potential combined effects are, and test those. This is what they would seem to have done and a combination was demonstrated to be potentially catastrophic in outcome and therefore the requirement is not met.

Boeing appear to have argued that this should not be categorised catastrophic outcome, rather major, on the basis that the pilot can catch it. They were proved and instructed otherwise. This would seem similar to the Flap System problem, we have little information on, but it seems Boeing had to be instructed it was catastrophic. Strangely enough, also seems a corollary of MCAS where at least some functioning engineers declared outcomes as major and have been proven catastrophically wrong. There might be an unchanging pattern here, but I’d be blowed if I can see it.

Ray


Ray, please send me a link so I can get educated. This would never happen on the military flight computers I worked on since the computers were “hardened”. I have always assumed commercial machines in airplanes had some type of protection, like a simple box around the processor.

I know we had occasional noisy inputs. But we filtered them to get rid of that random spike.

Looking forward to your link.


Delighted. I would expect most civil avionics these days are demonstrated compliant by component selection, defensive design and analysis rather than testing.

Publicly available. I like the NASA thing because its bullet points and does not try to confuse too much. The EASA doc is relatively short and readable.

https://spacemath.gsfc.nasa.gov/weekly/3Page6.pdf
https://www.easa.europa.eu/sites/defaul ... e%2001.pdf

Ray


Ray, thanks for the articles. I did note the issue was more significant at 100,000’ as opposed to 30,000. And I did notice they recommended a hardened computer. I understand that. Here is my mental problem with the a bit flipping correction in software. Let’s say the CPU fetches an instruction from memory but the opcode has a bit flipped. In case you don’t know, instructions are complex but they generally have a portion called the opcode that tells the CPU what to do, e.g., branch, add, or, etc. If one of those bits flipped, the CPU will probably halt. Or rather could halt. You don’t recover from that unless the hardware reboots and restarts. And we are talking possibly a fair amount of time. I get a hardened machine. I just have no clue how you recover in the case I mentioned. Maybe having 2 machines running makes the probability so low that that solves the problem? I dunno....but thanks anyway.
 
WIederling
Posts: 8472
Joined: Sun Sep 13, 2015 2:15 pm

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Thu Aug 08, 2019 7:06 am

MrBretz wrote:
.... I get a hardened machine. I just have no clue how you recover in the case I mentioned. Maybe having 2 machines running makes the probability so low that that solves the problem? I dunno....but thanks anyway.


You get bit flips from radiation in volatile memory cells ( RAM ).
Bit flip probability is a function of memory cell charge vs the particles charge potential.
i.e. the smaller the semiconductor structures are the higher the susceptibility.
( This makes RAM based programmable hardware "FPGA" a rather unattractive solution.
You use "hard burned" Fuse / AntiFuse architectures for this.)

Material shielding can actually be counterproductive.
High energy particles can kick off an avalanche of secondary particles in the shielding volume
that have exponentiated bit flip potential.
Murphy is an optimist
 
MrBretz
Posts: 349
Joined: Tue Jun 14, 2016 9:13 pm

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Thu Aug 08, 2019 7:20 am

Wledering, so you are saying the problem can be fixed in hardware. Are these types of computers used on a 737 or any other commercial airplane?
 
Some1Somewhere
Posts: 25
Joined: Thu Jun 25, 2015 2:22 pm

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Thu Aug 08, 2019 8:17 am

I think he's saying the opposite. Putting shielding around the computer can make things worse.

A hardware solution is only possible in the sense of a complete redesign.
 
User avatar
InsideMan
Posts: 331
Joined: Thu Aug 04, 2011 9:49 am

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Thu Aug 08, 2019 9:08 am

planecane wrote:
blrsea wrote:
I don't think Boeing will rush through the fix, or that the fix won't be the right one. They know that if another crash occurs, it will be catastrophic to the 737 program and pose serious threat to the company. I don't think anyone in Boeing is thinking that the first thing is to unground the planes rather than ensuring planes are fit to fly. I am sure they have double and triple checked the MCAS fix, and looked into every issue raised by FAA/EASA/other regulatory bodies with a magnifying glass.

They made a costly mistake once, and I don't think they will repeat it, at least not for a few years at least till people forget about this fiasco.


Great post! Boeing knows that if there is another MAX crash in the next 2 years it will be the end of the 737. Unfortunately, even if the pilot is recorded by liveatc saying he is going to crash into a mountain on purpose and then does it, the MAX design will still get blamed because the headlines will be "Boeing 737MAX Crashes into Mountain." They need to be absolutely sure that no design issue still exists that can lead to a crash. This is why, contrary to the opinions of some posters, I fully expect the MAX to have at least as good of a safety record as the NG going forward.


I'm sure that's the objective. Is it obtainable? That is the question.....
 
asdf
Posts: 304
Joined: Tue Mar 18, 2014 12:03 am

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Thu Aug 08, 2019 9:22 am

planecane wrote:
....Boeing knows that if there is another MAX crash in the next 2 years it will be the end of the 737. .....


it will be the end of the 737 programm if the next MAX crashes within the first six months after ungrounding

if the MAX crashes again after about two years its about 1500 MAX`s already flying
then the MAX programm is to big to fail anyway ...

maybe they simply try to reach that line ...
 
ArgentoSystems
Posts: 294
Joined: Sun Mar 24, 2019 12:05 am

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Thu Aug 08, 2019 11:57 am

Some1Somewhere wrote:
I think he's saying the opposite. Putting shielding around the computer can make things worse.

Please explain how it could make things worse
 
ArgentoSystems
Posts: 294
Joined: Sun Mar 24, 2019 12:05 am

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Thu Aug 08, 2019 12:09 pm

MrBretz wrote:
If one of those bits flipped, the CPU will probably halt. Or rather could halt. You don’t recover from that unless the hardware reboots and restarts.

It depends on which bit. if the resulting opcode becomes invalid, it will trigger an invalid opcode exception. Then it will be upto the software guy to recover,say, by restarting from the last known state.

But more likely it will turn one command into another. So best case it corrupt calculations. Worst, is program takes an unpredictable path. Which will likely result in either invalid opcode at some point or invalid memory access, etc. It will make recovery time somewhat unpredictable.

But this whole bit flipping thing is severely overblown. All you need to do is write your program in a way that minimizes reliance on long term data storage, which for FCC is only natural. You receive your input data, process it and calculate output. If data corruption happens, it will trigger only a momentarily upset (which should be filtered out in the next stages), next iteration you start from a new, freshly received set of data, so data corruption in previous will be immediately corrected.

And when you do rely on long term data storage, keep shadow copy and CRC protect both.
 
boerje
Posts: 34
Joined: Tue Jan 09, 2018 9:16 am

Re: Boeing 737MAX Grounded Worldwide Q3 2019

Thu Aug 08, 2019 12:52 pm

ArgentoSystems wrote:
Some1Somewhere wrote:
I think he's saying the opposite. Putting shielding around the computer can make things worse.

Please explain how it could make things worse


WIederling tried to explain this. High energy particles will penetrate the shielding and when this happens there will be not one (original particle) but many (secondary) particles causing havoc. "High energy particles can kick off an avalanche of secondary particles in the shielding volume that have exponentiated bit flip potential."
Last edited by boerje on Thu Aug 08, 2019 12:55 pm, edited 1 time in total.

Popular Searches On Airliners.net

Top Photos of Last:   24 Hours  •  48 Hours  •  7 Days  •  30 Days  •  180 Days  •  365 Days  •  All Time

Military Aircraft Every type from fighters to helicopters from air forces around the globe

Classic Airliners Props and jets from the good old days

Flight Decks Views from inside the cockpit

Aircraft Cabins Passenger cabin shots showing seat arrangements as well as cargo aircraft interior

Cargo Aircraft Pictures of great freighter aircraft

Government Aircraft Aircraft flying government officials

Helicopters Our large helicopter section. Both military and civil versions

Blimps / Airships Everything from the Goodyear blimp to the Zeppelin

Night Photos Beautiful shots taken while the sun is below the horizon

Accidents Accident, incident and crash related photos

Air to Air Photos taken by airborne photographers of airborne aircraft

Special Paint Schemes Aircraft painted in beautiful and original liveries

Airport Overviews Airport overviews from the air or ground

Tails and Winglets Tail and Winglet closeups with beautiful airline logos