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

 

[Alistair_Heaton]

There is no indication what the thumb switch positions are in. Only that the screw jack has recieved a manual (electric) trim input.

 

[IRstuff]

According to

https://www.reuters.com/article/us-...-to-read-an-aircrafts-black-box-idUSKCN1QV2ST

the FDR records 1790 parameters, although most of what I've seen says that it's at least 91 parameters, required by the FAA.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

faq731-376 forum1529 Entire Forum list

http://www.eng-tips.com/forumlist.cfm

 

[Alistair_Heaton]

Its not the FAA is ICAO annex 6 which dictates what's the minimum items recorded.

The document itself is extremely dry.

https://www.bea.aero/uploads/tx_scalaetudessecurite/use.of.fdr_01.pdf

That seems to be a reasonable summary of the whole thing from a french study on the subject.

These days they are downloaded every 2-3 days through the QDR and then the data in theroy used to check the pilots performance. Although it is very variable what individual companys do with that information once they have it.

 

[Alistair_Heaton]

Just as an interest point BEA have recovered the main disk from the 2017 disk failure of a A380 engine during flight.

https://www.flightglobal.com/news/a...engine-parts-found-under-greenland-sn-459399/

And how they did it.

https://www.bea.aero/uploads/tx_elyextendttnews/F-HPJE_TECHNICAL_REPORT.pdf

 

[VEBill]

"...are downloaded every 2-3 days through the QDR..."

AKA: Quick Access Recorder (QAR).

There was one accident where it was reported that the investigators were initially misled by the QAR data.

The QAR data was cut-off about a minute before the impact, so the investigators surmised some sort of electrical power failure that was thus perhaps a contributing factor to the crash

Later they figured out that the QAR, unlike an FDR, will buffer data before writing it to the non-volatile storage. This is done to manage the flash memory hardware (blocks, write cycles, lifespan). After all, there are no maximum latency requirements on the design, as supporting crash investigations is not its purpose.

So the final minute of data was lost in the buffer, and thus not recorded on the QAR's non-volatile memory. Thus causing temporary confusion.

They'd be well aware of this going forward.

 

[Alistair_Heaton]

The qdr is only for qa purposes of flight standards it will have nothing to do with the max investigation.

 

[VEBill]

"...only..."

In general, if a QAR memory unit survives and is found, then it certainly would be included in any air accident investigation. Just like any other available evidence. No reason not to do so.

Specifically for the Max:

I presume that any QAR module would have been destroyed in the ET302 crash.

But the Lion Air Preliminary Report (ref. KNKT.18.10.35.04) states, "The investigation has received the QAR data for flight for analysis" and "The KNKT has received the Quick Access Recorder (QAR) data for the accident aircraft since its delivery to Lion Air for analysis."

It's not clear if they're referring to QAR data for the incident flight, or previous flights, or both.

In any case, QAR data (if available) is certainly in scope.

 

[Alistair_Heaton]

It's only sampled every three seconds FDR is normally every second or more.

And the channels are not calibrated.

Yes if they find the data card which normally lives in a cockpit rack somewhere they will have a look at it the same as any phones they can find and the egpws memory and GPS logs. They will use anything and everything they can get their hands on. The advantage of qdr is it's relatively easy to read and load up in the company qa software. FDR has to be processed and not many places can do it.

 

[Alistair_Heaton]

What I suspect they are using it for is to see if there were any other mcas triggers which occured but the crew didn't report

 

[3DDave]

The United Kingdom are suggesting maybe all pilots need some training.

http://publicapps.caa.co.uk/docs/33/SafetyNotice2019005.pdf

Note that the graphs are misleading as it is unlikely a digital FDR can record a spike; it's sampling and the samples should be graphed as individual data points. For very short durations, one cannot extrapolate the integral of the area of a spike to determine the expected output.

Looks like data is fed to the FDR via a DFDAU

http://www.redimec.com.ar/contenido/productos/pdf/1425474436_1.pdf

 

[Alistair_Heaton]

Its a EU wide push in this area via EASA. The CAA is just the messenger to the UK AOC holders.

There have been several new topics come up over the last few years.

Flight upset and unusual atitudes came in 3 years ago with class room content and sim exercises. They monitor the global accidents and incidents and if they see a trend forming they start including the situation in the syllabus.

There is a move to reduce the separation in the terminal enviroment to basically try and fit more aircraft in the same airspace. The closer you get them together the more likely they are to encounter wake vortex.

They don't actually have a very predictable model of wake vortex how it moves or how it disapates. There are a few rules of thumb but basically you can't predict when your going to encounter it. It does kill, a calibrator recently in Dubai encountered it and went in 4 dead. Pilot was self seperating and screwed it up and paid the price.

So the system does react to changes in the operating enviroment and new risks that appear. No pilot will argue that training couldn't be improved. But your up against accountants, training is very expensive and disruptive to the airline cash flow. I know my Chief pilot would love to have 3 days of sim every 6 months currently he has 2 days which is 1 day more than legally required 3 days every 12 months. But there is no way he could sell that to the financial director. Currently there is that many hot topics that with the mandatory stuff of engine failures etc they are running out of time in the 3 sessions.

Pax will always take the cheapest seat, if your airline goes above the min required then its at a commercial disadvantage to the competitor that only does the bare minimum as dictated by the system.

Or are you expecting me and other pilots to stump up 2000 euro an hour to pay for additional sim training?

On the runway excursion topic there have been 7 go off road in the last 7 days.....

http://avherald.com/h?article=4c9d4a5a&opt=0

As I said if your going to go off road the 737 is the aircraft to do it in. How the hell that nose gear stayed on going through a drainage ditch I have no idea.

Hey I have an idea why not have every certifiying engineer have an exam every 6 months which will last 4 hours. Multi disapline including law will get fired at them every 15-30mins mins, they have 3 seconds to make a snap desision on which path they have to go down and then they have to play it out to the end. If its the wrong desision they fail and have to undergo retraining and loss of salary. The exam will done starting 4 hours into current sleep period. It won't be done at the place of work they will have to travel 4-5 hours the day before and then have 10 hours in a hotel, then 12 hours later do a second exam same setup. The previous 6 days they need to do 8-12 hour shifts and have at least 3 changes of start time.

On top of that every person involved with design and aircraft production will have to do 3 days of ground school, human performance, current legislation, best practise, and a day of case studys detailing screw ups and also the environment they are actually expecting people to operate the equipment in.

I suspect training/checking the Engineers and giving training to production first line crew will give more return than increasing pilot training.


I believe currently there is the sum total of zero training required or given at OEM level.


Our mainteners and operations staff have to go through 2 days a year of the CRM and case studys stuff. And it does make a difference.

 

[Alistair_Heaton]

And if anyone wants to see what the pilots get here is an example

I choose it because the subject is relevant to this topic.

https://youtu.be/WfNBmZy1Yuc

Unfortunately this video is now banned for training because it teaches the American way of dealing with flight upset using rudder to deal with roll. Apart from that its pretty good I think.

 

[VEBill]

"Pax will always take the cheapest seat..."

For long overseas flights, like wine in a restaurant, the 2nd cheapest offering is often a better choice.

[sub]Excuse the topic drift.[/sub]

 

[Alistair_Heaton]

I know that and you know that. But that's not the routes these planes will be flying. And not with the type of pax that appreciate the difference between any wine apart from the alcohol content.

If you ever get to speak to a revenue management team member and they open up on how they play the game its eye opening. Especially on contested routes.

Even a 5 euro/ 5$ price difference in seats can create 10k worth of losses or of profit on a route in days. Which is why having leap equipped hardware is so important. If you can save 14% of the fuel burn you have a huge margin to play with against none geared fans operators. You just need to drop your price to 5 below the others operating the route and you will still be in the green due fuel efficiency. They have higher running costs anyway and loosing the low yield traffic means their costs are not covered. Very quickly they have to pull out of the route. This then allows the other company to increase prices back above what they were before and generate even more revenue.

The longer the max is grounded with the neo getting pumped out at 55 a month the more likely that Boeing operators will just go bust. Just now they will have planned on MAX fuel burns with the ticket pricing so running it with other hardware will just add insult to injury. Hence early bird flight cancelations even if they have other hardware to operate the route.

Everything with high volume economy pax is about seat price. If a neo operator can charge 180 $ and a 737-800 operator has to charge 200$ the neo will be full and vastly profitable and the 737-800 will be struggling to break even more likely loosing money. Ancillary revenue will come into it but thats when it gets really crazy when you start talking about that side of things with a revenue managment type. Thats another thing that alot of pax don't look at. They just take the basic ticket price as there main decider and they are completely oblivious that once you add in all the extras that are included in the other carriers price its actually more expensive. Which is why most airlines now are dumping full service tickets. The pax want to pay for stuff individually and you will be hit hard if you don't allow it. So now its pretty much standard.

BUt they never get the reason why a A-B-C ticketed route is more than a A-B and B-C ticketed route. So they always go for the A-B, B-C then they are all over social media when they get dumped in some airport after missing thier connection because they have to recover baggage and deposit it again. They expect the airline is going to put them in a hotel and get the next avialble flight sorted to the destination. Well its the same airline as was selling the A-B-C ticket isn't it and they were late I missed the 30 min connection and they didn't hold the plane..... So they have to look after me.... well they would if you had paid a bit more for a A-B-C ticket but you thought you were being smart getting a cheaper ticket doing the same route. More than likely they had done the route multiple times before with no issues. Then they get caught once and it burns all the savings they have obtained from doing it 10 times previously. BUt if its 10 euro/$ cheaper to split the ticketing they will do it.

 

[Sparweb]

Woah,
RE: video posted earlier. Rudder hard-over and "cross-over angle of attack" in the training video - the instructor makes this disturbing statement:

"in the 757/767... if you are at flaps setting 5 and plus 40 on speed, you'd be there; you are at cross-over angle of attack. At that angle of attack or any higher your rudder is a more powerful roll control than your ailerons and spoilers. What I'm saying is that if the rudder is fully displaced by you or a malfunction, fully displaced roll controls in the opposite direction will not stop the roll [emphasis mine]

That's quite disturbing.

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

 

[Alistair_Heaton]

You deal with it by reducing power on one of the engines or increasing the other one. But you have a huge airbrake effect as well. But its not easy and you have an extremely small window to stay in controlled flight.

The dynamics of yaw and its effects are another area of pilot knowledge which is quite lacking.

When you get a yaw induced rollover you have very little time to reconfigure the power to retain controlled flight.

Here is a video of someone letting the speed go below Vmca on one fully functional engine. He had both engines running when he should have feathered the malfunctioning engine. An unfeathered prop at low power produces more drag than shutting it down and feathering it. So by keeping the engine going you actually raise the Vmca by a significant amount. Speed gets down to below Vmca and the rudder runs out of authority to balance the power on one side and the drag on the other and over you go. Pilots want to keep an engine running even if its producing minimal power. When realistically if it is producing anything less than about 10% torque its doing more harm than good. Now this only applies to prop aircraft. Jets don't produce as much adverse yaw at min power settings so keeping one of them ticking over may be advantageous to keep electric and hydraulic services.

https://youtu.be/YqmomTUVsAw

 

[moon161]

"Woah,
RE: video posted earlier. Rudder hard-over and "cross-over angle of attack" in the training video - the instructor makes this disturbing statement:
Quote (Captain Warren VanderBurgh)
"in the 757/767... if you are at flaps setting 5 and plus 40 on speed, you'd be there; you are at cross-over angle of attack. At that angle of attack or any higher your rudder is a more powerful roll control than your ailerons and spoilers. What I'm saying is that if the rudder is fully displaced by you or a malfunction, fully displaced roll controls in the opposite direction will not stop the roll [emphasis mine]

That's quite disturbing."

That's another chapter of the 737 story, there were two 737's lost to a rudder control issue.[edit: several more suspected] They rolled in when the rudder jammed hard over.

https://en.wikipedia.org/wiki/Boeing_737_rudder_issues

 

[VEBill]

Bloomberg: Boeing 737 Max's Autopilot Has Problem, European Regulators Find

...EASA’s checklist includes a number of issues that have been disclosed: the potential difficulty pilots have in turning the jet’s manual trim wheel, the unreliability of the Max’s angle of attack sensors, inadequate training procedures, and a software issue flagged just last week by the FAA pertaining to a lagging microprocessor. But the agency also listed a previously unreported concern: the autopilot failing to disengage in certain emergencies. ...

 

[Alistair_Heaton]

The power of discussion groups like this...…

As I said I am sure someone else would have spotted it but when I sent the email to one of the EASA tech pilots it seemed they hadn't spotted it yet.

I really can't see how Boeing can get it flying again without redesigning the trim system.

There is another aviation news site which is behind a pay wall that's reporting there is a list with over 200 items on it that need fixing with the FAA. But the manual trim issue is not on it.

I really can't see how it will be allowed to fly in Europe again without them fixing the trim system. And if EASA require it the rest of the other Global authorities will want it fixed as well.

I can't see it flying next summer season now to be honest. September is just an executives dream world. And the more testing they do the more problems they will find.

 

[Alistair_Heaton]

I didn't realise that the FAA was leaderless at the moment.

https://www.ft.com/content/b98ccbfa-9f27-11e9-b8ce-8b459ed04726