Boeing 737 Max8 Aircraft Crashes and Investigations [Part 4] 28

[Sparweb]

This is the continuation from:

thread815-445840
thread815-450258
thread815-452000

This topic is broken into multiple threads due to the long length to be scrolled, and many 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.

My personal point of view, since this falls close to (but not exactly within) my discipline, is the same as that expressed by many other aviation authorities: that there were flaws in an on-board system that should have been caught. We can describe the process that "should have happened" in great detail, but the reason the flaws were allowed to persist is unknown. They are probably too complex to reveal by pure reasoning from our position outside of the agencies involved. Rather, an investigation of the process that led to the error inside these agencies will bring new facts to light, and that process is under way, which will make its results public in due time. It may even reveal flaws in the design process that "should have" produced a reliable system. Every failure is an opportunity to learn - which is the mandate of the agencies that examine these accidents.

Some key references:

Ethiopian CAA preliminary report

Indonesian National Transportation Safety Committee preliminary report

The Boeing 737 Technical Site


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

 

[VEBill]

This is the "Engineering Failures & Disasters" forum. So the focus of this thread is supposed to be on the engineering failures (hardware and software design flaws, questionable decision making) associated with the Boeing 737 Max disasters.

 

[Alistair_Heaton]

I would hope that the lack of realistic human interaction with an engineering system which then leads to disaster would also come under the remit.

If things are being designed for some mystical super human that has the same response at all times and the response doesn't vary individually. Then they are really not fit for use.

 

[Sparweb]

The comment wasn't pointed at any particular member. Just a friendly reminder to try to stay focused on the main topic. Auto ABS (braking control when wheels are in contact with the ground) is a subject pretty far removed from flight control system integration problems (adjustments when the aircraft is aloft).

Although... if you do want to discuss patterns you see in other kinds of software/hardware interfaces and the unintended kinds of failures that can occur, there's a meaty topic there. You're welcome to start a new topic yourself, any time you want.


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

 

[davefitz]

One would like to think that the final resolution of the 737 max failures would rigorously meet all defined safety standards , but the extreme financial pressure being placed on both the airlines and Boeing will ultimately imply political pressures will be applied to all of the international safety agencies to quicken the official resolution while wordlessly accepting ( ie winking at) some compromises .

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

 

[Lou Scannon]

Today I happened to be checking flights for prospective trip overseas in November. I was a little surprised to see some of the equipment listed as 737Max8. This was an EU airline.

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

 

[Alistair_Heaton]

The Canadians have kicked it out of the winter season timetable.

The winter timetable in the EU won't be finalised until end of next month.

And even then it's subject to change on the events occurring on the 31st of Oct in the UK.

There could be a huge drop in flights which will sort the hardware supply issues out. UK accounts for 25% of intra EU sector pairs.

There has been a remarkable lack of any information on recertification in Europe.

I haven't heard any date likely this year. And next summer season is not seen as definite by a huge margin.

There is a very interesting artical in the WSJ behind a paywall on the whole pilot reaction time subject.

 

[3DDave]

I think 5 months should have been long enough.

 

[Alistair_Heaton]

It might have been if Boeing had bit the bullet from the very beginning instead of putting max effort into blaming the pilots. But now they are into double figures number of issues which are outside certification and its basically immaterial what the pilots did. Even if the reports come out and say that the pilots did every single thing wrong, which is highly unlikely. The testing that has been done since has proved that the type should never have been released in the first place.

Now they are going for dual processing and cross check and this side of the pond anyway they are going to have to certify the whole of the flight control system to fly by wire certification standards.


And the big elephant in the room is the manual trim system. Which nobody wants to talk about because it also effects the NG.


25 months is not outside the realms of possibility now.

And even when they do get it flying again, then the next crash with any hint of control issues and that will be the type dead as a dodo.

 

[3DDave]

It was long enough for the pilots and their airlines to decide on whether to risk it.

But neither wanted to give up their paychecks did they?

 

[Lou Scannon]

Slight tangent to the thread; there must be considerable insider knowledge brewing within Boeing with regard to the future stock price. I take no direct part in the stock market, but I wonder if those "in the know" are taking any advantage, illegally, of course. I suppose any trading of Boeing or key supplier stocks by those with potential insider information will be receiving appropriate scrutiny.

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

 

[Alistair_Heaton]

From the grounding the pilots flying them and airlines have zero input about when the plane flies again.

That's not completely true on the part of the pilots because in Europe anyway there are various pilot groups who do have an input into various aspects of the situation and what is a reasonable compromise in relation to the human interaction with the machine and sensible response times to comprehend and solve issues. But they certainly don't have the final say in the matter.


Even if they want to risk it as you put it, thankfully they can't.

And you are correct that some accountant would risk it for a gain in their bonus. If it was up to them they would continue flying it, pilot training would be reduced, we wouldn't carry alternate fuel, if the engines start you would go flying and pilots would work 14 days in a row straight with 8 hours rest a day and 200 hours in the air a month. Mind you on that last point I can think of several people on their 3 or 4th divorce who would be more than happy doing that.

But now people who are in charge of when it flies again have zero financial interest in it flying again this side of the pond. And they are also outside the political arena and pressure of the home country of manufacture.

They also now have control over the certification of the 777 program faa mutual recognition is out the window.

777x which is already late and has issues. And similar to the 737 MAX and NEO its competitor the A350 is already certified and flying.

I might add the 777 is a 1980's grandfather design up against a clean sheet 2006 design which by all accounts was pre designed for future options for ultra long haul and several other variants.

And we haven't even touched on the changes to the regulations and certification standards that will occur because of the MAX.


The fall out from the MD merger is in its end game. We shall just have to wait and see what comes out the other side. Its in nobodys interest world wide for Boeing to collapse. But it really doesn't seem as if their is anyone in the organisation who can bite the bullet and move on from the true Boeing days and design. Lets face it nothing new has come out of Boeing since the merger. Even the 787 was the product of pre merger decisions in the early 90's. All thats occured is reacting to Airbus products and hitting the market years after they have been flying after having mucked about shoe horning together something from a 1960's to 1980's tech and design.

Then they released a killer aircraft which is going to end up costing them more and taking more time than if they had clean sheeted it in the first place. But the managment and accountants will keep thier bonuses that they recived during its developement.

Lets face it modern aircraft require composites, the 777x will be boeings first composite wing spar. Its 20 odd years behind the other OEM's. The MAX is just a symptom of the cancer in Boeing and in the FAA.

 

[Alistair_Heaton]

Oh and to note two pilots didn't do the OEM's procedures or company procedures.

Didn't put the gear down and everyone is alive again.

https://youtu.be/XRb8bTM6RFY

On an a engineering note. This is the second time those engines have had bird strikes with small species and its ended up with dual engine failure at low level and the pilots have done completely the right thing and sacrificed the hardware to protect the contents both times not doing it as per the SOP'S.

Although to note it looks like they had one strike after V1 on the runway and then another strike shortly after rotate which took the other engine out.


I would like to hope there will be some work done on those GE engines to see if there is soomething funny going on which wasn't picked up with the bird strike testing during certification. Which from memory is a single standard bag of gelotine with some bones in it fired through a large bore air gun with the engine running at max power. Multiple small species is not tested to my knowledge.

 

[LittleInch]

Is it really procedure to try and land not on a hard surface with gear down??

I remember watching a program a few years ago where they deliberately crash landed a plane in Mexico by remote control with the wheels down and one thing that they found was that whilst the main gear promptly broke off as it was designed to, the nose wheel didn't and dug into the ground causing the front part of the fuselage to break off.

The main wheels though became a loose very large object and could easily puncture wings or fuselage after impact.

The profile of the 321 implies the jet actually skidded along on the engines... The right hand engine does appear to have come away at the last minute.

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

 

[Alistair_Heaton]

yes the theory being that even if they break off it absorbs energy with its destruction.

oh to add its is recommended to try and land with the gear down preferably on a runway. These guys like sully didn't have that option. The idea that you can hang a turn just after takeoff and do a 180 and land again has been rubbished for a good 30 odd years now. Statistics show the most likely outcome is the plane stalling and crashing halfway through the turn or spinning in from low level. Picking a clear spot straight ahead usually has a more successful out come be it in a Cessna 150 or a Seneca through to an A320. There are people that do it and get away with it don't get me wrong, They are usually in extremely STOL types with amazing glide ratio, such as super cubs and the like with stupidly low stall speeds. One of my favorite tricks in a super cub was to takeoff in 15knts of wind climb and at about 750-1000ft come back to just above stall speed then we would be seen to reverse down the runway. There is zero chance I would even attempt it in say a PA38 tomahawk unless above 1000ft. The super cub 500ft wouldn't be a problem. But at the speed they fly at if your on a 2000 meter runway you don't need to turn round anyway from 500ft you just stick the flap out and land straight ahead and still have 1000 meters of runway in front of you.

It does work the 777 that crashed in Heathrow it reduced the touch down G to survivable limits. BTW that was also an initial pilot screw up flying to high when it was cold. BUt the Captain did save the day in the end by taking in drag flap which allowed the aircraft to impact in relatively clear ground before the runway instead of going into the houses outside the airport boundary.

That said the gear was up on the 777 in DXB when the pilots screwed up a go around and sank back on and everyone one survived that one as well. I suspect it more to do with angle you touch down at, than if the gear is down or not.

We don't use it on water because it will dig in and cartwheel as you describe.


To be honest in this crash I doudt very much if the gear would have been down and locked anyway with no hydralics apart from the RAT at V2 speeds even if they had selected it immediately the second engine started rolling back.

Sully went outside procedure and started the APU out of sequence to the QRH as a memory action, which gave him electrics and hydralics before the computers went off line and then would have been rebooted when the APU came back on line which would have taken vital seconds. the alpha protect mode stopped the aircraft from stalling so it touched down with minimum speed. It will be interesting to see what this Captain did and what mode the flight logic was in.

Here is a pic of the 777 at Heathrow where you can see what happend to the gear. And my mate was working in the tower when it happened as an ATCO. We still give him stick about it.

 

[davefitz]

A month ago there was a rumor that Boeing would be restructured into 2 entities, military aircraft and civilian aircraft, so that the military section would survive a bancruptcy of the civilian section. As with similar bancruptcies of large corporations, the assets ( including personnel, patents and infrastructure, could then be sold to another entity, which might be a conglomerate of other investors. I do not think the civilian part would actually dissapear into the ether.

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

 

[LittleInch]

Without going too far off track the heathrow 777 was just about to touch down and very nearly made the runway. Rather different to a corn field.

that pic is my point - gear down damage could easily rupture fuel tanks or end up in the cabin. The right hand gear set detached.

It looks like there were recommendations out of that crash about what happens to the main landing gear to try and prevent fuel tank rupture, but leaving the landing gear up would be one way....

If you look at the skid marks I think the engines did most of the slow down.

Anyway on the 737 story, it does seem to have gone into a hole at the moment - Mid sept being the consensus for sending the details of the "fixes" to the FAA. Reading between the lines, It looks like it will be difficult to get re-certification / approval to fly without mandatory training in a SIM.

This is the WSJ link if you can get it for free- very illuminating, but not much on what the proposed changes are going to be.

https://www.wsj.com/articles/the-four-second-catastrophe-how-boeing-doomed-the-737-max-11565966629

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

 

[Alistair_Heaton]

the 777 at Heathrow didn't have any options it failed when they were in final landing configuration with the gear down. The captain managed to get the flap up to lift flap only and then seconds later they impacted.

The RAT has limited power and I doubt very much if they could have retracted the gear even if they wanted to. Retracting and extending gear vastly increases drag while the doors are open. So if they had tried they would have gone into the houses.

Anyway someone did the calcs and reckoned with out the main gear going up through the main spar it would have been over 8g touch down or some such magic number which would have meant the floor seat mounts collapsed with a 85kg adult in them. The plane did its job and everyone survived which is the main thing. They were also lucky it had been raining a lot.

I suspect details of whats required have been deemed market sensitive now and we will only find out whats happening via compnay releases to the stock market or however it works in the USA.

The FAA are only the first point of contact. Even if they say its ok doesn't mean the rest of the worlds regulators will ok it.

The interesting bit is going to be how the certification regulations are changed afterwards.

 

[LittleInch]

For sure, two different scenarios so different ways of dealing with it. One had wheels down and couldn't retract, the other probably had wheels up and couldn't be sure about getting them down in time.

That 777 pretty much fell out of the sky alright but with that damage it was lucky not to catch fire. I read that it landed with 3+G so maybe it avoided the complete pancake and no time to do anything else. They got it over the A30 which wouldn't have been good to land on, but didn't quite make the runway. Anyway I get the points made.

I think you're right in terms of details of what is happening on the 737 being much more locked down than before for the planned modifications.

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

 

[Alistair_Heaton]

I think they are still arguing the toss about what has to be dealt with. And the list keeps increasing as they are discussing it.

The primary flight control system they have bitten the bullet on and basically gone flybywire.

The trim system is still and will be a bone of contention.

I have no doubt they will find other issues while certifying the new primary control system.

Then the arguments about training will start. Then there will be flip of many faces who have said it was all the pilots fault for not performing properly, they will then revert to no need for them to go to the sim they can do it all through self study at home and no need to go to the sim. Then when the next crash happens it will be back to useless incompetent pilots again.

Eastern Airways managed to smack a Jetstream 32 off the runway in Wick with 5.6g..... they had prop strikes but taxied it off the runway..... they only found out that they had split the main spar when they tried to put fuel in it and it started pissing out the wheel well.

There was a recent one in Canada with a Q400 which was over 4g and it flew for 3 days before the FDR was download and they discover it was a write off.

BTW a landing isn't deemed worthy of additional inspections until over 2.2G on the Q400. My record is 1.6G and that felt like it was a crash and we were shot down.

The 777 would have virtually no fuel in it and it was cold soaked for 9 hours and was below its wax point which was what they think might have been the issue. Jet A is a complete and utter swine to light if its cold soaked. I have spent many an hour freezing my nuts off with "trumpton" trying to get a tray of it alight so we can pull a pin out of a fire extinguisher check it works then put the tray out. Below 15 degrees you can throw flaming rags in it and it won't light. They used to have to resort to a butane torch on a rag in it in Aberdeen training centre for 10 mins before it would light up. Working in the middle east with air temps above 35 degrees whole different ball game. Its normally heated by a oil cooler to heat it before it goes into the engine to be burnt and any excess returned to the tank to try and keep the temp up of the rest of it.

 

[waross]

Is this the article you linked, Alistair?
Same authors.
Same first paragraph.
No Pay wall.

https://www.msn.com/en-us/money/com...ophe-how-boeing-doomed-the-737-max/ar-AAFTIuc

Bill
--------------------
"Why not the best?"
Jimmy Carter