Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5] 19

[Sparweb]

This is the continuation from:

thread815-445840
thread815-450258
thread815-452000
thread815-454283

This topic is broken into multiple threads due to the length to be scrolled, and images to load, creating long load times for some users and devices. If you are NEW to this discussion, please read the above threads prior to posting, to avoid rehashing old discussions.

Thank you everyone for your interest! I have learned a lot from the discussion, too.

Some key references:
Ethiopian CAA preliminary report

Indonesian National Transportation Safety Committee preliminary report

A Boeing 737 Technical Site

Washington Post: When Will Boeing 737 Max Fly Again and More Questions

No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
STF

 

[MartinLe]

I've come across this article and thought to share it:

https://newrepublic.com/article/154...-air-ethiopian-airlines-managerial-revolution

It's more about the management side of the disaster, but seems to confirm some speculations in the thread above - there was a real incentive to not retrain pilots for the new system, so it was omitted from some manuals, the MAX design was built into an existing FAA certifiaction and others.

 

[thebard3]

I've come across this article...

I don't think I would just take everything reported here as factual, but nonetheless it's consistent with my experience. No matter the management culture promoted by a company, it's subject to change drastically and rapidly because management personnel change and bring different priorities, skill sets, and experience (or lack thereof) with them. Warren Buffet once said the he would only buy a company that an idiot could run, because eventually an idiot would probably end up running it.

Brad Waybright

It's all okay as long as it's okay.

 

[thebard3]

Some recommendations from the NTSB, none of which are related to modifications necessary to get these ships back in the air.

https://www.ntsb.gov/investigations/AccidentReports/Reports/ASR1901.pdf

Brad Waybright

It's all okay as long as it's okay.

 

[LittleInch]

Maybe not but my reading / understanding of this is that the NTSB found that the testing of the MCAS simulated only the resultant AND action and didn't actually simulate an AOA input error / disagree which resulted in multiple alarms and actions as the incorrect data spread to other systems such as the stick shaker and other alarms. It's not clear ever if the Boeing assessment or testing realized that the AND just kept on happening 5 seconds after trimming back.

Also the assessment assumed or was based on the ability to return to steady flight using the available column ALONE or trim. That's the key one where it's been shown you can't do that and you can't manually trim.

It is now recommending basically that ALL the 737MAX safety assessments which rely on the pilot(s) making "immeadiate and appropriative corrective actions" are reassessed and incorporate design improvements, procedure and appropriate training....)

So now Boeing and others need to not only consider the impact of an event ( uncommanded AND in this instance) but also the impact of the initiating event (bad data, failure of instrument etc) on other systems which result in multiple alarms leading to pilots finding difficulty in identifying the root cause and corrective action.

WOW.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Alistair_Heaton]

It's part of the grandfather stuff. They only have to test the system changed. They don't have to do the big picture.

Over the years they have added multiple additional aural warnings TCAS egpws and the like go through the cockpit speaker, gear warning has its own horn. So does airspeed high. Stick shaker generates its own noise. I haven't yet seen anything formal about which alarm has priority. Your meant to use "airmanship" to decide which one to tackle first.

 

[Alistair_Heaton]

A NG related issue

https://www.reuters.com/article/us-...or-cracks-on-some-737-ng-planes-idUSKBN1WD02E

They more than likely use the same on the MAX but no MAX airframe will have the hours to be anywhere near it being an issue. But they may have to replace the pickle forks on the parked aircraft before they are delivered or agree to pay for it at the first heavy check.

 

[LittleInch]

Link won't work.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Alistair_Heaton]

try this one

https://www.reuters.com/article/us-...or-cracks-on-some-737-ng-planes-idUSKBN1WD02E

 

[Sparweb]

Brad,
Thank you for linking the update. That is a very interesting read. The NTSB is getting out ahead of the FAA here, and I'm glad they are doing this. By sharing its findings as quickly as possible, rather than delivering all results of the investigations at once in the final accident report, they can emphasize the similarities in the accidents and the design errors that led to them. This will have repercussions with all of the world authorities examining the Max certification, not just the FAA. If it also ties the hands of the FAA to offer no easy backdoors to Boeing, then it's also good.

This particular document, despite its length, is actually a highly distilled set of conclusions and recommendations, which reveals plenty of what the NTSB thinks was going on in those cockpits. There was a lack of sensible information being provided to the crews, no training to deal with the particular situation, and low odds that they would be able to sort it out before the problem evolved beyond the point of recovery. The NTSB is clearly coming down on the side of bad design, and I am pleased to see that they lay NONE of the blame at the feet of the flight crews.

http://www.sparweb.ca

 

[Sparweb]

Hi Alistair,
The Reuters article you linked just makes noise about a very minor and completely unrelated issue.
The affected aircraft are old and heavily used. The tiny cracks were found because there is a commendably thorough and detailed inspection program being used to look for this damage, and find it long before it becomes a threat. This is evidence that the system works.

http://www.sparweb.ca

 

[Alistair_Heaton]

I realise that, to be honest I just thought it might be of interest.

I have had my finger inside a crack in concordes tail and it flew a week later. And I worked for 2 years on nonlinear fea models and validating my models of cracks in nuclear pressure vessels. So I am quiet familiar with the condition monitoring side of things for allowing acceptable cracks.

If the pickle forks are the same though on the MAX and the life of them is reduced then the undelvered aircraft will need contract changes to account for this or the issue rectified before delivery. Changing the pickle forks will required the wing box to come off. All the NG's it is now the operators problem for inspections and rectification. MAX it will significanlty increase the life cost of the aircraft so while they are still on Boeings ownership books its their problem to sort out. With any luck it will be an material issue with a batch of pickle forks. If its a design issue then its another thing on the list.


On the subject of blame... Accident investigation never lay blame as such they anlaysis what happened and then recommend to stop it happening again. Blame is only decided by courts of law. And quite often it doesn't go the way people expect.

The Shoreham accident in the UK in 2015 had quiet a few of us suprised at the outcome of the court case and was at odds with the accident report.

 

[thebard3]

There was a lack of sensible information being provided to the crews, no training to deal with the particular situation, and low odds that they would be able to sort it out before the problem evolved beyond the point of recovery.

Right. Also, they note in some way something I learned many years ago. Given equal amounts of education and training, some folks have a better (or different) understanding of things than others. Also, Some are better troubleshooters than others and some perform better under pressure. That's just the way it is and to expect a pilot to always understand exactly what might be wrong with their airplane, take appropriate action, and absent that, to blame them if the thing crashes isn't a helpful philosophy.

Brad Waybright

It's all okay as long as it's okay.

 

[Alistair_Heaton]

I have flown with the phyco nurse of one of the Cray brothers. I have also flown with the number 2 celloist of the royal philomonic. Both have a completely different time scale and problem solving thought process than I do as a Mech Eng.


Btw signed both of them off into the lhs as captains of commercial jar25 aircraft

 

[Alistair_Heaton]

H'mm 7.5 Bn of trade tarrifs kiss good bye to max flying again in easa land for the next year.

It seems us punters are going to test the fix.

 

[RVAmeche]

Boeing 737 Max Safety System was Vetoed

Boeing has provided a complaint by an engineer to the DOJ as part of a criminal investigation in the design process of the Max

 

[Alistair_Heaton]

https://www.seattletimes.com/busine...x-certification-requirements-for-crew-alerts/

More on grandfather excemptions on the MAX.

 

[davefitz]

I agree with the comments on the assignment of blame by the courts- it can go either way. As a "good citizen" one is expected to presume the assignment of judges is random and the selected judge is not compromised, but with a major corportation facing an existential threat together with the potential " national security " implications of having the banckrupt assets purchased by mandarin-speaking entities, it is possible that "dirty tricks" may be rationalized.

"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick

 

[LittleInch]

I didn't realize what this $7.5Bn was about, but here it is

https://www.bbc.co.uk/news/business-49906815

Now in theory it shouldn't impact the issue with Max, but .... The 10% duty on EU aircraft being a particular issue.

I had heard something about whiskey being taxed at 25% but thought it was just an ongoing tit for tat trade deal thing, not directly related to aircraft.

Note that there is also an ongoing US govt aid to Boeing issue being waged in the WTO to be determined later.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[dgallup]

Price of Scotch is going up, time to start hoarding.

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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

 

[Alistair_Heaton]

well I do feel sorry for the malt drinkers in the USA. Bourbon is rank.

Airbus already have the Mobile production site for A320 and A220 so it doesn't really matter for them.

Airframe orders are done 5-6 years in advance so its the USA consumers who will have to foot the bill. Will make zero difference to sales they already occured 6 years ago.

And the max won't be flying any time soon for quiet legitimate reasons.

Plus USA has a finding against them from the WTO for similar reasons so it just going to hurt everyone.

But thats into politics not engineering or aviation...