Ethiopian Airlines Crash/ B737MAX grounding

john boye

cnocbui wrote: »

Lol!



https://www.cnbc.com/2019/06/17/boeing-records-zero-new-plane-orders-as-paris-air-show-starts-slow.html

Slightly different today!

kmart6

john boye wrote: »

Slightly different today!

20 Dreamliners for Korean if people are wondering.

https://www.google.com/amp/s/www.cnbc.com/amp/2019/06/18/boeing-lands-its-first-new-order-for-airplanes-at-the-paris-air-show.html

Graham

200 737Max for IAG

"I have great confidence in Boeing and great confidence in the Max. It will make a great addition to our fleet," says IAG chief executive Willie Walsh.

"This has been a tough negotiation," he adds. "It's a good deal for us and I hope a good deal for Boeing."

https://www.flightglobal.com/news/articles/paris-iag-signs-for-200-max-jets-459119/

john boye

Graham wrote: »

200 737Max for IAG



https://www.flightglobal.com/news/articles/paris-iag-signs-for-200-max-jets-459119/

Would be amazed if this ever comes to fruition but it's a great boost for the Max programme nonetheless.

Blut2

The FT today had an article on it:

https://www.ft.com/content/e8e017f4-91d5-11e9-aea1-2b1d33ac3271

Paywalled, but the most interesting highlight is:

Although the order is valued at $24bn at list prices, IAG will have received discounts. Analysts suggested the actual value of the deal could be worth around $11bn.

Thats a pretty steep discount - 55% off.

Tenger

That’s “Ryanair c. 2002” levels of discount!

Graham

Meanwhile in a non descript conference room in Swords, a small battalion of HR bods are mulling over the potential consequences of IAG slurping vast quantities of 737 flight crew out of the market.

Tenger

Graham wrote: »

Meanwhile in a non descript conference room in Swords, a small battalion of HR bods are mulling over the potential consequences of IAG slurping vast quantities of 737 flight crew out of the market.

Not just ‘out of the market’, out of their current contracts!

plodder

Graham wrote: »

200 737Max for IAG



https://www.flightglobal.com/news/articles/paris-iag-signs-for-200-max-jets-459119/

That's one up for Willie Walsh. fair play to him. I'd say MOL is fuming - being outdone at his own game. Not just on getting a big discount, but announcing it with nolittle regard to the prevailing sense of gloom about the aircraft.

nsa0bupkd3948x

Two people in work have said they're not going to fly BA anymore since they buy unsafe aircraft.

Obviously wrong on many levels but interesting to hear.

Graham

By the time these aircraft start arriving at IAG the current Max issues will be long forgotten.

That's assuming the LOI ever moves into a firm order.

josip

Layman here so apologies for any loose terminology.


Has it been decided that the 737 MAX will retain the same type certification as the 737?
I thought in the immediate aftermath of the crashes, that one of the problems identified was that the plane fundamentally flies differently to the 737 and that trying to mimic the behaviour with software was not acceptable even if they did manage to correct the sensor bugs?

Graham

I think the suggestion all along has predominantly been this is a software issue with a software fix.

josip

Graham wrote: »

I think the suggestion all along has predominantly been this is a software issue with a software fix.

Wasn't that Boeing's suggestion which the airlines were happy to go along with for cost reasons?
Do the pilots also believe this and the (compromised) FAA and EASA ?

cnocbui

Graham wrote: »

I think the suggestion all along has predominantly been this is a software issue with a software fix.

It seems to me very likely there is a fundamental problem with the design of the AOA sensor, so I doubt this is a software only fault. I think a bird-strike is believed to have damaged the Ethiopian AOA sensor. So two problems that aren't software: The design, and there only being one.

plodder

josip wrote: »

Layman here so apologies for any loose terminology.


Has it been decided that the 737 MAX will retain the same type certification as the 737?
I thought in the immediate aftermath of the crashes, that one of the problems identified was that the plane fundamentally flies differently to the 737 and that trying to mimic the behaviour with software was not acceptable even if they did manage to correct the sensor bugs?

Layman here also, but I think the suggestion has been that it flies differently in certain situations, but fundamentally differently? I'm not so sure.

Someone can correct me if I'm wrong but I don't think either of the two crashes were affected in any way by this different flight characteristic. It was ironically and tragically a failure of the system that would correct this behaviour, but the behaviour itself never arose.

The biggest part of the mistake made by Boeing was downplaying (and hiding even) the difference. They now have to live with this perception that the difference is "fundamental" as you are asking. But, that's entirely their fault.

Graham

I thought the issue was only one of the AOA sensors was connected to MCAS so if it got damaged, bad things happened. Single point of failure.

I don't remember if the 2nd one required hardware changes to be bought into use.

In essence, the hardware wasn't faulty. They just weren't using all/enough of it!

Added:

I think the disagree light was a hardware issue. This should have highlighted where 2 AOA sensors showed different readings.

troyzer

The problem is that the system was originally designed to improve handling at high speeds. MCAS was designed to assist this with two sensors inputs: AOA and accelerometer. MCAS would require both of these inputs to hit certain thresholds before activating.

But they also found later that there were issues with the plane stalling at low speeds. So they decided to use MCAS to fix that as well. But accelerometers wouldn't be affected by a low speed stall so they had to remove that as a trigger for MCAS.

So what happened was that without the right people being informed, MCAS could now be triggered by a single point of failure: one AOA sensors.

This was a result of design creep that didn't increment enough to require FAA approval.

The 737 already has two AOA sensors, the fix is both software related to curb MCAS' aggression and add the second sensor for redundancy.

I have no idea why it wasn't always connected to two sensors.

Bob24

Graham wrote: »

I thought the issue was only one of the AOA sensors was connected to MCAS so if it got damaged, bad things happened. Single point of failure.

I don't remember if the 2nd one required hardware changes to be bought into use.

In essence, the hardware wasn't faulty. They just weren't using all/enough of it!

Added:

I think the disagree light was a hardware issue. This should have highlighted where 2 AOA sensors showed different readings.

Isn’t there also an issue whereby the MCAS gets triggered at a stronger angle and for a longer duration than what was originally agreed upon with the FAA?

If yes and while technically it is a software change could make the system more light handed, could there not be an underlying hardware issue for Boeing if they make that change? I.e. if they change the software to lighten the effect of MCAS, won’t the manoeuvring characteristics of the plane drift away from previous 737s, meaning either a hardware change will be required to fix the aerodynamics or 737 pilots transition to the MAX might require recertification.

Graham

I can't see how they're going to significantly change the aerodynamics unless they take off the engines and fit smaller ones further back. De-max the aircraft for want of a better description.

If it's a case of applying less power for shorter durations, that sounds more like changing software/parameters.

I haven't come across any sort of official suggestion that pilots will need recertification. That's not to say it won't happen but I would expect Boeing to push-back against it.

errlloyd

Bob24 wrote: »

Isn’t there also an issue whereby the MCAS gets triggered at a stronger angle and for a longer duration than what was originally agreed upon with the FAA?

Right so I could be wrong on this but I believe this is what happened.

The MCAS design the FAA saw was 0.6 degrees of pitch down if the plane detected a stall. The final design was actually 2.5 degrees of pitch down if the plane detected a stall. But if the stall was corrected by the pilots manually, but the sensor was still off the MCAS could pitch down 2.5 degrees again (for a total of 5 degrees down) and repeat this process.

flexcon

I believe the reason they went with one sensor input to trigger MCAS was it could then be self certified.

If they went with two sensors then they could not self certify and need additional pilot training?

I also recall how the pilots didn’t even know this system existed.

Going on memory of the news reporting in the US mind you.

Graham

flexcon wrote: »

I believe the reason they went with one sensor input to trigger MCAS was it could then be self certified.

My understanding is they only 'got away' with one sensor because they were allowed to self certify.

MCAS was given a 'hazardous' failure condition, it should have had 2 levels of redundancy.

As it turns out, a catastrophic failure condition would have been more appropriate (can endanger the aircraft and its passengers).

Bob24

errlloyd wrote: »

Right so I could be wrong on this but I believe this is what happened.

The MCAS design the FAA saw was 0.6 degrees of pitch down if the plane detected a stall. The final design was actually 2.5 degrees of pitch down if the plane detected a stall. But if the stall was corrected by the pilots manually, but the sensor was still off the MCAS could pitch down 2.5 degrees again (for a total of 5 degrees down) and repeat this process.

Thanks. If this is correct I guess the next question is to know why Boeing decided to go for twice 2.5 degrees correction rather than the 0.6 degrees which were submitted to the FAA.

If there reason is that 0.6 degrees is not sufficient to correct the trajectory and make the plane behave in the same way as an “old” 737, don’t they have a potential serious issue which can’t be fixed with a simple software change? (Unless the FAA agrees to the twice 2.5 degrees thing, but I assume they will proceed with extreme care)

Bob24

Graham wrote: »

I can't see how they're going to significantly change the aerodynamics unless they take off the engines and fit smaller ones further back. De-max the aircraft for want of a better description.

If it's a case of applying less power for shorter durations, that sounds more like changing software/parameters.

I haven't come across any sort of official suggestion that pilots will need recertification. That's not to say it won't happen but I would expect Boeing to push-back against it.

Yes agreed. I guess big questions now are: why did they go for stronger trajectory correction than the design they had submitted to the FAA, and would the FAA agree to that stronger level?

Graham

Bob24 wrote: »

the next question is to know why Boeing decided to go for twice 2.5 degrees correction rather than the 0.6 degrees which were submitted to the FAA.

According to an article in the Seattle Times:

That limit was later increased after flight tests showed that a more powerful movement of the tail was required to avert a high-speed stall, when the plane is in danger of losing lift and spiraling down.

Source: Flawed analysis, failed oversight. Seattle Times

Bob24

Graham wrote: »

According to an article in the Seattle Times:



Source: Flawed analysis, failed oversight. Seattle Times

Thanks. So basically it seems like Boeing needs the FAA to agree to increase the angle compared to what they had originally approved, or the plane won’t behave as it should.

I assume the FAA will want to facilitate this, but I wouldn’t like to be the person(s) accountable for such decision.

Graham

I don't think the changes/solution have been made public yet.

I am fairly certain the solution stretches beyond the FAA approving what was previously in place.

Irish Steve

Graham wrote: »

I think the suggestion all along has predominantly been this is a software issue with a software fix.

That's a massive over simplification of what's happened.

The MAX has larger engines mounted higher and further forward, which has had significant effects on the way the airframe handles, with specific issues having been found at high angles of attack, the new engine nacelles produce additional lift, and as this is a long way ahead of the C of G position, it is more significant.

The MCAS system is supposed to intervene at high angles of attack to put additional down trim in to overcome the additional lift, but for all sorts of reasons, it's not worked the way that it was expected to, and to make things worse, the initial training information about the MAX was significantly lacking in information about MCAS, both in terms of what it does, how it does it, and any possible failures.

To make it worse, the overall software has been "tweaked" in order to try and make the MAX handle as closely as possible to the earlier 737 generations, to reduce the training load and requirement, and avoid the need for a different type rating for the Max.

The Final nail in the coffin is that the MCAS system was only operating on the data from one signal source, so if that source failed or was damaged, there is no way for the aircraft to know that the input into the MCAS determination could be significantly flawed, with the result that inappropriate trim changes could be made at unexpected times.

It would seem that the FAA were blind sided by Boeing, and changes to MCAS that made it more powerful in effect over a wider aspect of the flight envelope went through "on the nod", without anyone really questioning the actual overall implications of those changes.

Given what's happened, and subsequently come out of the woodwork, I suspect that FAA will be ultra paranoid now to make very sure that Boeing have truly resolved the issues, and I'd like to hope that EASA and other regulators will not let the MAX be brought back into service without carrying out their own in depth evaluations of the changes that have been made in order to ensure that there are no shortcomings in the fix that is eventually approved.

Graham

Irish Steve wrote: »

That's a massive over simplification of what's happened.

Absolutely it is, quite intentionally.

Additional detail added in subsequent posts.

Turbulent Bill

Irish Steve wrote: »

Given what's happened, and subsequently come out of the woodwork, I suspect that FAA will be ultra paranoid now to make very sure that Boeing have truly resolved the issues, and I'd like to hope that EASA and other regulators will not let the MAX be brought back into service without carrying out their own in depth evaluations of the changes that have been made in order to ensure that there are no shortcomings in the fix that is eventually approved.

I'd imagine that they'll be looking at a lot more than just MCAS. The media reports demonstrate that, as well as the FAA being asleep at the wheel, Boeing gamed their own risk analysis to avoid having to add sensor redundancy to MCAS. Any diligent regulator would look for evidence that other systems were appropriately risk managed.

Jeff2

Was it not that the second sencor was optional and both plains that crashed didn't have it.

Popeleo

Jeff2 wrote: »

Was it not that the second sencor was optional and both plains that crashed didn't have it.

I think you are confusing a couple of related issues. IIRC all
MAX planes had two sensors and used the same version of MCAS which used the data from one sensor only.

There were two optional safety systems related to this. The first showed when there was a conflict between the sensors. I think the second showed the angle of ascent/descent given by the same sensors. The second could be argued as being optional but the first was essential.

In my view, that design decision was criminally negligent. It smells of downplaying the risk to avoid regulatory scrutiny - an undergraduate engineering or computing student could design a better system. How hard can it be to use both inputs and disable MCAS in the case of a conflict?

Jeff2

I think the tail wings went from normal to 12.5 degrees up the rear and nose down in about 25 seconds.

They lasted 45 seconds to respond to something they didn't know about.

Tenger

cnocbui wrote: »

It seems to me very likely there is a fundamental problem with the design of the AOA sensor, so I doubt this is a software only fault. I think a bird-strike is believed to have damaged the Ethiopian AOA sensor. So two problems that aren't software: The design, and there only being one.

Nope. The bird strike theory was postulated by a Boeing exec. Investigators in response have ruled out any evidence of foreign object damage.

Your logic is a bit askew. The AoA design could be perfectly fine. But systems can fail. The use of only one is a systems flaw.

murphaph

Turbulent Bill wrote: »

I'd imagine that they'll be looking at a lot more than just MCAS. The media reports demonstrate that, as well as the FAA being asleep at the wheel, Boeing gamed their own risk analysis to avoid having to add sensor redundancy to MCAS. Any diligent regulator would look for evidence that other systems were appropriately risk managed.

Exactly. This was a corporate culture problem, not an isolated mistake. Boeing took advantage of the system to allow more and more self certification with tragic consequences. A thorough review of the entire certification of the MAX is really required. I just hope EASA is forthright enough with their FAA colleagues on this. I will not be setting foot on one in any case for a couple of years.

Hotblack Desiato

josip wrote: »

I thought in the immediate aftermath of the crashes, that one of the problems identified was that the plane fundamentally flies differently to the 737

Irrespective of it flying like a 737NG or not, the MAX was not certifiable without MCAS. Stick force decreasing with increasing pitch is not permitted.

cml387

I'm reminded of the Hawker Siddeley Trident, where a vice in the aircraft (an unrecoverable deep stall) was overcome by a mechanical stick push which would force the control column forward if no action was taken by the pilot in an incipient stall condition.

MCAS is really no different and the MAX will be certified eventually.

It's rather sad though that Boeing had to be so reticent about how the system worked. It's rather as if Boeing's corporate culture forbade them from mentioning that this rather crude fix was required.
I read once about Boeing's engineers being upset about incorporating a yaw damper,it being their belief that a mechanical device should not be required to fix a flaw in an aircraft design.

xtradel

https://www.youtube.com/watch?v=46InmJexzYg

Spot the Ryanair...

L1011

The operation to return to normal, deliveries wise, is going to be immense when it can finally start.

The limited number of NGs rolling out and actually being deliverable is tailing off now too - only a handful left in the system at all. So everything coming off the line will need storage somewhere.

Bob24

xtradel wrote: »

https://www.youtube.com/watch?v=46InmJexzYg

Spot the Ryanair...

Not sure airlines whose name/logo can be seen on this video will be too pleased :-D Some people might look at the video as a directory of airlines which have ordered that new Boeing airplane which is crashing.

Shedite27

xtradel wrote: »

https://www.youtube.com/watch?v=46InmJexzYg

Spot the Ryanair...

Have they made changes to the production yet? I think I read there were optional extras that they were going to provide as standard. Would that all have been included on these planes, or are they waiting for signoff on that before the fix it.

What I'm trying to say, are these planes ready to fly once certified or are they the in the same boat as a Max that was flying 6 months ago?

Blut2

That aerials video doesn't even show the build-up as obviously as it shows in photos. Some of them look almost like modern art:





If the delay runs into 2020 I've no idea where they'll store them. Even with the monthly production rate cut to 42 (as I believe it is now) there'll be hundreds by that stage.

Cookiemunster

I believe the second pic is Southwests already delivered grounded fleet. I've seen an aerial version of the same pic

trellheim

Are they being maintained in fully flyable condition ?

GM228

Cookiemunster wrote: »

I believe the second pic is Southwests already delivered grounded fleet. I've seen an aerial version of the same pic

Correct, that's their grounded fleet at Victorville Airport.

GM228

trellheim wrote: »

Are they being maintained in fully flyable condition ?

No, the engines are sealed and regularly the fuel is tested for any contamination.

Weekly and daily care schedules sees spooling of the turbofans, booting up flight computers, extending and retracting flight-control surfaces such as wing flaps etc.

But, each plane would require an estimated 30 day exam programme before being fit to fly.

banie01

This problem would be far simpler for Boeing to rectify if the Max was a true FBW airframe.

I do feel that given the handling and aerodynamic changes with the Max airframe that separate type certification should be called for.

That will come with huge cost implications for both Boeing and purchasing Airlines, but the software fix is not at all appropriate to the revised airframe.

murphaph

banie01 wrote: »

This problem would be far simpler for Boeing to rectify if the Max was a true FBW airframe.

I do feel that given the handling and aerodynamic changes with the Max airframe that separate type certification should be called for.

That will come with huge cost implications for both Boeing and purchasing Airlines, but the software fix is not at all appropriate to the revised airframe.

Surely Boeing can't persist with this iPad training is enough line after all that's happened?

banie01

murphaph wrote: »

Surely Boeing can't persist with this iPad training is enough line after all that's happened?

IMO thats exactly what Boeing will aim for.
Its the only way they can ensure that sales and adoption of the Max will continue at the pace envisaged pre-crashes.

I don't think its the correct approach, and while the FAA may be bent to Boeing's will I really do think that Europe and other regulatory bodies will call for a new type certification and kill off the single cockpit rating for 737ng and MAX.

The MAX is a fundamentally different airframe and bolting on an electronic fix to a non-FBW airframe is a flawed and cheap assed approach to try and save money on conversion training and adoption costs.

The airframe may well develop into a safe and trusted plane, it won't do that without re-certification though IMO.