Ethiopian Airlines Crash/ B737MAX grounding

wonski

john boye wrote: »

Part of me wonders if Ryanair's announcement today is with a view to cancelling their max order (or long-term postponing it) or if they know something that we don't about the future of the max programme.

He clearly stated non delivery from Boeing and resignation rates close to zero play big part.

Other airlines are affected, too, hence staff movement is probably much lower than ever.

Sounds legit. They have to take precautions in case of complete failure of Max being delivered. That does not mean they know something, but obviously they know more than us.

Shedite27

Watched the Panorama last night, a few questions.

A bit of it mentioned that the single AOA sensor was a design fault, but even with two sensors, how would a computerised system have known which one was correct. Even with two, if one acted up, it would have required the pilots to intervene, which evidently they weren't trained to do.

When this first came out, there was a mention of additional safety features (that were sold as an extra). Where did they fit in the puzzle?

And finally the software update, do we know what that's going to fix?

L1011

There's two schools of thought over whether 3 AoA sensors and a voting system is better or not as it creates a potential dual failure overruling the last working one... but it'd actually need both to fail almost identically to "win" the voting.

Bob24

Shedite27 wrote: »

Watched the Panorama last night, a few questions.

A bit of it mentioned that the single AOA sensor was a design fault, but even with two sensors, how would a computerised system have known which one was correct. Even with two, if one acted up, it would have required the pilots to intervene, which evidently they weren't trained to do.

When this first came out, there was a mention of additional safety features (that were sold as an extra). Where did they fit in the puzzle?

And finally the software update, do we know what that's going to fix?

Two sensors are indeed not sufficient to implement a majority voting system (you need at least 3), but they are sufficient to detect that something is wrong with one of the sensors (ie if the 2 sensors disagree, one of them must be faulty and the system can display a flashing red warning for the pilot which should lead to immediate maintenance).

This warning mechanism is what Boeing had as an optional paying feature.

I don’t remember the exact details of the 2 crashes, but I believe for at least for one of them it was proven that sensors disagreement had been happening previously to the flight, but the airline didn’t have the optional warning package so no alarm was displayed in the cockpit. Had the alarm been present the pilot would quite possibly have decided not to fly the plane and it could have prevented the crash.

And just to clarify: the Max does have 2 sensors (hence the sensors disagree feature), but the MCAS only relies on one sensor at a time to make decisions.

Van.Bosch

Bob24 wrote: »

Two sensors are indeed not sufficient to implement a majority voting system (you need at least 3), but they are sufficient to detect that something is wrong with one of the sensors (ie if the 2 sensors disagree, one of them must be faulty and the system can display a flashing red warning for the pilot which should lead to immediate maintenance).

This warning mechanism is what Boeing had as an optional paying feature.

I don’t remember the exact details of the 2 crashes, but I believe for at least for one of them it was proven that sensors disagreement had been happening previously to the flight, but the airline didn’t have the optional warning package so no alarm was displayed in the cockpit. Had the alarm been present the pilot would quite possibly have decided not to fly the plane and it could have prevented the crash.

And just to clarify: the Max does have 2 sensors (hence the sensors disagree feature), but the MCAS only relies on one sensor at a time to make decisions.

Imagine designing a somewhat robust safety feature to alert pilots to an issue and not activating it unless the customer chooses to pay for it. How that was ever allowed by regulators is baffling.

Bob24

Van.Bosch wrote: »

Imagine designing a somewhat robust safety feature to alert pilots to an issue and not activating it unless the customer chooses to pay for it. How that was ever allowed by regulators is baffling.

Sounds crazy indeed. To be honest, I think both Boeing and the FAA completely failed to understand how critical the AoA sensors and the MCAS had became with the Max design changes compared to the NG, and didn’t treat these things with sufficient precautions (they originally didn’t even bother telling pilots about the MCAS and how it works, assuming the people flying the plane didn’t even need to know about the system).

Bob24

Was just reading an interview of the CEO of Air France KLM.

There was a question on the Max and he’s saying that for now he wouldn’t consider ordering any Max, and that for the parts of the business which are using the 737, the strategy if new planes are needed would be to buy second hand NGs as there are plenty available on the market (it might actually get harder to find and more expensive if other airlines are thinking the same thing).

cnocbui

Van.Bosch wrote: »

Imagine designing a somewhat robust safety feature to alert pilots to an issue and not activating it unless the customer chooses to pay for it. How that was ever allowed by regulators is baffling.

Easy to allow under self regulation. :rolleyes:

josip

Layman here so please correct me if I've made incorrect assumptions.

The FAA is coming in for a lot of criticism but has there been any criticism of the EASA?
Before the MAX ever flew, shouldn't the EASA have considered that a regulator outsourcing oversight to a supplier is in principle never going to end well and they should have ramped up their own verification and inspection rather than just accepting the FAA rubber stamping?

cnocbui

Not really. This is the first major breakdown in the FAAs oversight in decades with negligible fatalities in the US due to faulty planes. Also, with Trump, there would have been a risk of the tiny tot shrilly screaming that it was just another protectionist measure by those scheming communist EU people; so here, have a sanction.

Having two bodies requiring independent certification of every major plane is actually incredibly wasteful, expensive and 'should' be unnecessary if both bodies were performing their roles properly.

This has come about due to the steady evolution of the US into a commerceocrasy, where everything has been made subservient to the financial interests of commerce.

josip

When the A320 Neo received joint certification from EASA and FAA, did they share the regulatory and verification work or was it all done by one and accepted by the other?

funkey_monkey

https://www.seattletimes.com/business/boeing-aerospace/newly-stringent-faa-tests-spur-a-fundamental-software-redesign-of-737-max-flight-controls/

The fault occurs when bits inside the microprocessor are randomly flipped from 0 to 1 or vice versa. This is a known phenomenon that can happen due to cosmic rays striking the circuitry. Electronics inside aircraft are particularly vulnerable to such radiation because they fly at high altitudes and high geographic latitudes where the rays are more intense.

A neutron hitting a cell on a microprocessor can change the cell’s electrical charge, flipping its binary state from 0 to 1 or from 1 to 0. The result is that although the software code is right and the inputs to the computer are correct, the output is corrupted by this one wrong bit.

You'd like to think they have some type of parity checks and accommodation for this. It would seem that they did not.

One standard way to fix such a problem is to have the second independent microprocessor inside the same flight-control computer check the output of the first. If the second processor output disagrees with that of the first processor for some specific automated flight control, then no automated action is initiated and the pilot must fly manually.

“Now it takes two processors to fail to get the bad result,” the person familiar with the tests said. “You are no longer in the realm of a single point failure.”

So they had a single processor fed by a single input??? Where was the redundancy in this system.
Most aircraft systems would run dual channels with independent inputs which are cross checked between the channels. I really can't understand how they got this certified - but I guess that is why they didn't certify it at the correct DO178 level.

Shedite27

funkey_monkey wrote: »

I really can't understand how they got this certified - but I guess that is why they didn't certify it at the correct DO178 level.

Watch the panorama, they cself-certified. FAA were cutting costs so don't want expensive inspectors on their payroll, hence Boeing are allowed do their own verifictions. Clear conflict of interest.

Turbulent Bill

I'm getting suspicious about the FAA's recertification activities here. The probability of 5 specific bits being flipped simultaneously by radiation is infinitesimal. Even low earth orbit satellites (bombarded with radiation) don't need to cover multiple failure scenarios such as this.

So why test for such a low probability event, when surely there are more likely failures up the food chain? My guess here is that the FAA want to force Boeing into using redundant control (no bad thing), and this is a means to an end. Doesn't inspire confidence though if they're focusing on just one issue, rather than looking at a wider risk analysis.

Jeff2

The thing to look at is the second sencor was available on all planes but only activated if it was paid for as an optional extra

Both planes that went down didn't have it. .

plodder

This hardware bit flipping stuff isn't new. I don't know why it's coming up now. The talk of new "software architecture" is more concerning though. You'd hope it is something that has been in development for some time as it's not something that could be rushed out the door in response to a problem like this. Either that or it's a misuse of the term 'architecture' in a software context. It makes it sound like a fundamental redesign, which is certainly not something you would be releasing any time soon.

Shedite27

plodder wrote: »

This hardware bit flipping stuff isn't new. I don't know why it's coming up now. The talk of new "software architecture" is more concerning though. You'd hope it is something that has been in development for some time as it's not something that could be rushed out the door in response to a problem like this. Either that or it's a misuse of the term 'architecture' in a software context. It makes it sound like a fundamental redesign, which is certainly not something you would be releasing any time soon.

Sounds like a spokesman trying to sound all techie without really knowing what's going on. Happens a lot in my company. CTO in the background with his head in his hands

The One Doctor

Somehow I believe that whatever software fix Boeing comes up with, EASA will refuse to accept it. The 737 just wasn't built for those engines.

Bob24

The One Doctor wrote: »

Somehow I believe that whatever software fix Boeing comes up with, EASA will refuse to accept it. The 737 just wasn't built for those engines.

The EASA will have to be very careful there. On the one hand they will need to show they are acting in the interest of safety of European air travel and aren’t taking for granted what a foreign regulator says; but on the other hand they could quickly be accused of being a tool for protectionism (especially in the current political climate). So if there are serious safety concerns which are legitimate reasons to refuse the fix, they will have to publicly and clearly demonstrate those and thus they would quite clearly be calling the FAA incompetent for accepting these things.

All this will be very political ...

Nijmegen

Bob24 wrote: »

The EASA will have to be very careful there. On the one hand they will need to show they are acting in the interest of safety of European air travel and aren’t taking for granted what a foreign regulator says; but on the other hand they could quickly be accused of being a tool for protectionism (especially in the current political climate). So if there are serious safety concerns which are legitimate reasons to refuse the fix, they will have to publicly and clearly demonstrate those and thus they would quite clearly be calling the FAA incompetent for accepting these things.

All this will be very political ...

In fairness the FAA approach to regulation could attract the same accusation. Anything to do with aircraft production, purchase, etc, is political - actually less so since EU state aid rules and deregulation / privatisation of the national airlines came through. Back in the day a lot of frames were purchased solely because govt financed their development to keep the industry alive and then pressured their airlines into buying them.

The US is actually probably the biggest source of indirect state aid, for all they moan about ME3 carriers and what have you, to the aviation industry. From FAA regulation framework to military contracts that go back to square one when Boeing or Lockheed don't win them...

Bob24

Nijmegen wrote: »

In fairness the FAA approach to regulation could attract the same accusation. Anything to do with aircraft production, purchase, etc, is political - actually less so since EU state aid rules and deregulation / privatisation of the national airlines came through. Back in the day a lot of frames were purchased solely because govt financed their development to keep the industry alive and then pressured their airlines into buying them.

The US is actually probably the biggest source of indirect state aid, for all they moan about ME3 carriers and what have you, to the aviation industry. From FAA regulation framework to military contracts that go back to square one when Boeing or Lockheed don't win them...

Yes agree with all of that, I certainly didn’t mean to imply the EASA is more politicised that the FAA (I also think it is the opposite).

But still they’ll have to be careful with how they handle this.

cnocbui

Bob24 wrote: »

The EASA will have to be very careful there. On the one hand they will need to show they are acting in the interest of safety of European air travel and aren’t taking for granted what a foreign regulator says; but on the other hand they could quickly be accused of being a tool for protectionism (especially in the current political climate). So if there are serious safety concerns which are legitimate reasons to refuse the fix, they will have to publicly and clearly demonstrate those and thus they would quite clearly be calling the FAA incompetent for accepting these things.

All this will be very political ...

An EU US trade war is probably inevitable given the current crazies running that asylum, so I don't think EASA should hold their punches out of fear. Unfortunately, I think Europe needs a trade war with the US just to correct some of the weird-think that is going on in bombastic isolationist US heads, despite the damage that would ensue.

Bob24

cnocbui wrote: »

An EU US trade war is probably inevitable given the current crazies running that asylum, so I don't think EASA should hold their punches out of fear. Unfortunately, I think Europe needs a trade war with the US just to correct some of the weird-think that is going on in bombastic isolationist US heads, despite the damage that would ensue.

Not holding their punches ... but making sure they have a full and indisputable technical explanation ready as well as political backup before any announcement; and being prepared for a damaged work relationship with the FAA which could affect other things (again, if they are calling unacceptable something the FAA says is fine, they’ll be publicity calling the FAA incompetent - which even if it was true would damage the relationship).

banie01

That the proposed fixes for the growing list of issues with the Max all seem to involve adding further electronic control and command systems, to what is in essence a mechanical linkage flight control system is quite worrying.

The addition of sticking plaster fixes is one of the primary drivers in the issues with this airframe.
It is an airframe, that if it wasn't grandfathered in would not be certified.

Adding further electronic control overlay to what are essentially mechanical systems is not at all an appropriate manner in which to address the issues.

The longer it goes on, the more I really do feel Boeing would be better served in their long term by pulling the plug.

ZX7R

Could they replace the existing engines ,with a new design or replace with an older version

Jeff2

ZX7R wrote: »

Could they replace the existing engines ,with a new design or replace with an older version

Don't think so, they couldn't go with the older ones anyway because of the changes to the plane to use the engines they now have.

It is very different to other 737s but was past as one when it shouldn't.

Jeff2

It's a longer plane so more seats.

An engine that pulls from the front rather than pushing from the back like the other 737s.

Different wing with engine forward and higher.

How is this not a different plane and need certification.

Car99

Jeff2 wrote: »

It's a longer plane so more seats.

An engine that pulls from the front rather than pushing from the back like the other 737s.

Different wing with engine forward and higher.

How is this not a different plane and need certification.

1. Nearly all type have longer and shorter versions with more seats.

2. A MAX leap 1B is a high bypass gas turbine same as CFM56 .

3. Same wing different pylon design.

All 3 are not an issue for type certification it is the change in flight characteristics of the MAX v the NG that is the issue.

Jeff2

Car99 wrote: »

1. Nearly all type have longer and shorter versions with more seats.

2. A MAX leap 1B is a high bypass gas turbine same as CFM56 .

3. Same wing different pylon design.

All 3 are not an issue for type certification it is the change in flight characteristics of the MAX v the NG that is the issue.

Well that is what I was saying, but you said better.

Order wise it would not need the aoa sencors to trim the back to make sure it didn't stall while in flight and hit the ground.

Which is what happened.

L1011

ZX7R wrote: »

Could they replace the existing engines ,with a new design or replace with an older version

Any higher efficiency engine is going to be of a similar size. The CFM56 already had to be squashed to fit on the older pylon, hence the "hamster pouch" look to it

Rawr

L1011 wrote: »

Any higher efficiency engine is going to be of a similar size. The CFM56 already had to be squashed to fit on the older pylon, hence the "hamster pouch" look to it

How about the other way around? Could the 737's clearance from the ground be increased with modifiactions to it's design? Could this be feasible at all?

My highly un-educated guess is that if the clearance could be brought up to A320-ish hights, then that Leap engine will fit under the wing in a position that may not require MCAS correction.

I remember seeing something ages ago about 737 Classic being designed to be close to the ground due to a customer demand. I can't remember the details of that, but perhaps it is time to ditch that requirement for the sake of better engines?

L1011

That would probably require a new type cert. And the plane is uncertifiable as a new type for countless reasons

The closeness to the ground was to allow easy ground ops - integral airstairs and baggage without a loader. Earlier small jets had fuselage mounted engines so were low anyway

troyzer

Rawr wrote: »

L1011 wrote: »

Any higher efficiency engine is going to be of a similar size. The CFM56 already had to be squashed to fit on the older pylon, hence the "hamster pouch" look to it

How about the other way around? Could the 737's clearance from the ground be increased with modifiactions to it's design? Could this be feasible at all?

My highly un-educated guess is that if the clearance could be brought up to A320-ish hights, then that Leap engine will fit under the wing in a position that may not require MCAS correction.

I remember seeing something ages ago about 737 Classic being designed to be close to the ground due to a customer demand. I can't remember the details of that, but perhaps it is time to ditch that requirement for the sake of better engines?

You'd have to completely redesign the landing gear and it would definitely affect the aerodynamics too much.

All of this would have been considered by Boeing. Realistically there is no way of getting what they wanted.

They might have to scrap the program.

Graham

Rawr wrote: »

My highly un-educated guess is that if the clearance could be brought up to A320-ish hights, then that Leap engine will fit under the wing in a position that may not require MCAS correction.

I vaguely recall the Max has been heightened slightly but they reached the limits of what was possible without a major redesign of the fuselage and wings.

You'll get an idea of the space limitations if you watch the gear retraction in action:

https://www.youtube.com/watch?v=F4IGl4OizM4

https://www.youtube.com/watch?v=Yam_JNDT8io

josip

Graham wrote: »

I vaguely recall the Max has been heightened slightly but they reached the limits of what was possible without a major redesign of the fuselage and wings.

You'll get an idea of the space limitations if you watch the gear retraction in action:

https://www.youtube.com/watch?v=F4IGl4OizM4

https://www.youtube.com/watch?v=Yam_JNDT8io

Surprised they've left comments enabled for the first video considering they're all negative.

adam88

IF they scrap the max program could it bring down Boeing ?

L1011

adam88 wrote: »

IF they scrap the max program could it bring down Boeing ?

US Government would ensure that didn't happen. "forced marriage" to Lockheed or Northrop Grumman or somehow isolating Boeing Commercial Aircraft from the parent firm for instance.

They'd ensure that the military division was entirely protected and I suspect they'd interfere further to protect the commercial arm also to prevent commercial transports becoming a solely European and Japanese game (Embraer commercial is already wrapped in to Boeing)

In a market where there weren't military and geopolitical concerns; scrapping the MAX would drive Boeing out of existence; as would another year or so of a grounding. But that market doesn't exist.

Hotblack Desiato

Jeff2 wrote: »

The thing to look at is the second sencor was available on all planes but only activated if it was paid for as an optional extra

Both planes that went down didn't have it. .

That's incorrect.

All MAXes had two AoA sensors and used one AoA sensor to feed into MCAS - this alternated between the sensors from one flight to another.

What was optional was a system to indicate whether the two AoA sensors were in disagreement with each other. But even with this option installed, MCAS only took input from one sensor at a time.

Bob24 wrote: »

if they are calling unacceptable something the FAA says is fine, they’ll be publicity calling the FAA incompetent

FAA have already, very publicly in front of a global audience, demonstrated themselves to be incompetent.

L1011

I get the feeling that Norwegian have been told the MAX isn't coming back for quite some time in a sufficiently official manner to lead to todays pulling of routes.

Locker10a

L1011 wrote: »

I get the feeling that Norwegian have been told the MAX isn't coming back for quite some time in a sufficiently official manner to lead to todays pulling of routes.

I'm not so sure, theres a lot to suggest those routes just weren't commercially performing

Car99

L1011 wrote: »

I get the feeling that Norwegian have been told the MAX isn't coming back for quite some time in a sufficiently official manner to lead to todays pulling of routes.

Will that kill Norwegian? Their choice of a Boeing fleet has really hurt them , first the 787's woes and now the MAX I'm surprised theyre still operating.

Blut2

I would think the 737MAX issues aren't the worst turn up for Norwegian. Their biggest problem recently was having a massive order book of planes, which was forcing them to expand much too rapidly - often to airports that didn't have enough demand to sustain their service profitably (ie Cork and Shannon here).

Given that, if Boeing are not delivering the 737MAXs and giving financial compensation to Norwegian instead, it mightn't be a bad thing for them.

edit: just to add some figures because I was curious and went off to check: Norwegian had 99 planes in service at the start of 2016, 118 at the start of 2017, 144 at the start of 2018, and 165 at the start of 2019. And they've another 86 737MAXs on order, (with 6 already delivered and now grounded). Thats an absolutely breakneck expansion pace.

zilog_jones

Locker10a wrote: »

I'm not so sure, theres a lot to suggest those routes just weren't commercially performing

The Examiner article claims they were wet-leasing replacement planes, so maybe they could have been profitable if they were able to use their MAXs?

https://www.irishexaminer.com/breakingnews/business/norwegian-ends-unsustainable-transatlantic-flights-from-ireland-943632.html

Locker10a

zilog_jones wrote: »

The Examiner article claims they were wet-leasing replacement planes, so maybe they could have been profitable if they were able to use their MAXs?

https://www.irishexaminer.com/breakingnews/business/norwegian-ends-unsustainable-transatlantic-flights-from-ireland-943632.html

They were struggling and culling routes from Ireland and Scotland well before the MAX grounding. In January/Feb Dublin crew and been informed the majority of them wouldn't be retained in Dublin and would have to bid for a transfer to another base. That was before there was any hint of MAX issues.

Dublin was going to be reduced to a skeleton operation from this October, with maybe 1 or 2 aircraft being based, this would have meant routes would have been served 2/3 times weekly. Things were slowly winding down, the MAX grounding has expedited this.

banie01

More issues for Boeing with the KC-46 contract.
They are on the hook for the costs of redesigning the flying boom and the remote camera systems.
This is on top of previous issues that led to the USAF suspending delivery of ordered airframes due to QC issues.
That multiple Boeing programmes are encountering quality and programme management issues is surely a concern and indicative of a cultural issue at senior level.
https://www.flightglobal.com/news/articles/boeing-juggles-kc-46-tanker-deliveries-and-boom-rede-460233/

Airbus must be rubbing their hands with glee thanks to tying up with Lockheed for a new tanker bid!
Given that EADS/Northrop original KC-45 bid was likely beaten by illegal Boeing state aid, tying up with a bigger player wil really turn up the heat.
This story is from December 2018, but Boeing's star has only fallen further since then.
https://www.defensenews.com/air/2018/12/05/lockheed-airbus-venture-ups-the-pressure-on-boeing-to-deliver-its-us-air-force-tankers/

L1011

McDonnell management took down Douglas and they're taking down Boeing basically.

coolshannagh28

adam88 wrote: »

IF they scrap the max program could it bring down Boeing ?

How is Boeing still trading at 3.20 a share ?

banie01

L1011 wrote: »

McDonnell management took down Douglas and they're taking down Boeing basically.

Yep.
I've been banging the drum on the KC-46 issues for a while and TBH I do think that the incestuous links with Boeing and the Pentagon are going a long way towards shielding Boeing from immediate programme cancellations at this point.

There is so much poor management control and oversight that is being left "fly" excuse the pun

GM228

banie01 wrote: »

More issues for Boeing with the KC-46 contract.
They are on the hook for the costs of redesigning the flying boom and the remote camera systems.
This is on top of previous issues that led to the USAF suspending delivery of ordered airframes due to QC issues.
That multiple Boeing programmes are encountering quality and programme management issues is surely a concern and indicative of a cultural issue at senior level.
https://www.flightglobal.com/news/articles/boeing-juggles-kc-46-tanker-deliveries-and-boom-rede-460233/

Airbus must be rubbing their hands with glee thanks to tying up with Lockheed for a new tanker bid!
Given that EADS/Northrop original KC-45 bid was likely beaten by illegal Boeing state aid, tying up with a bigger player wil really turn up the heat.
This story is from December 2018, but Boeing's star has only fallen further since then.
https://www.defensenews.com/air/2018/12/05/lockheed-airbus-venture-ups-the-pressure-on-boeing-to-deliver-its-us-air-force-tankers/

It would seem Boeing are only on the hook for the remote vision fix, and that they won a $55M contract to redesign the boom telescope actuator according to that article and the GAO report also is not clear on this (does this suggest someone else designed it and Boeing won a contract to fix it, because if Boeing designed it in the first place they would need to fix it and would not be getting a $55M contract to do so).

The USAF will be paying $300M towards the costs of fixing the problems, but are also withholding 20% of payments due to Boeing until they are fixed.

What's more interesting is the GAOs caims it could take 3 to 4 years to fix and receive FAA certification, the KC46 programme is already 3 years behind schedule as it is.

banie01

GM228 wrote: »

It would seem Boeing are only on the hook for the remote vision fix, and that they won a $55M contract to redesign the boom telescope actuator according to that article and the GAO report also is not clear on this (does this suggest someone else designed it and Boeing won a contract to fix it, because if Boeing designed it in the first place they would need to fix it and would not be getting a $55M contract to do so).

The USAF will be paying $300M towards the costs of fixing the problems, but are also withholding 20% of payments due to Boeing until they are fixed.

What's more interesting is the GAOs caims it could take 3 to 4 years to fix and receive FAA certification, the KC46 programme is already 3 years behind schedule as it is.

Given US reliance on tankers both for deployment and as a force multiplier that won't go down to well in Washington I'd imagine.