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Delays in Boeing Max Return Began with Near-Crash in Simulator

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Re: Delays in Boeing Max Return Began with Near-Crash in Simulator

#81

Post by Merrill »

dk- wrote: post #72
Merrill wrote: post #69

Earlier quoted context omitted.

>Landing contracts for key systems on the Max cemented a relationship with Boeing that Collins had long cultivated, in part by creating what its chief executive in 2002 called an “enormous sea change in a very long legacy business." For years, the company had been “a technology leader, an innovator,” Clayton Jones, then the chief executive, told Fortune magazine. “Unfortunately, along the way they forgot to hone thei…

not likely the NG didn't add new systems. not saying other cost-cutting won't be exposed but nothing as egregious as MCAS. the MAX added new engines, which required forward placement on the wings, which changed COG, which necessitated MCAS.

They changed flight control computers from Honeywell to Collins when going from the 737 to the 737 NG. Seems like a new system.

Re: Delays in Boeing Max Return Began with Near-Crash in Simulator

#82

Post by Operyl »

NovemberWhiskey wrote: post #40
Operyl wrote: post #24

Earlier quoted context omitted.

In the article they mention that they outsourced at least some of it. “ As Boeing and the subcontractor that supplied the flight-control computer, the United Technologies Corp. division Collins Aerospace Systems, worked through these changes, it has at times created tension.”

It is extremely common that various parts of design and manufacture of aircraft are "outsourced". The airframe manufacturer is essentially never the manufacturer for whole subsystems and there is a large subcontracting network. This is an entirely normal and long-standing practice.

Didn't say it wasn't, I was just answering GP's question :).

Re: Delays in Boeing Max Return Began with Near-Crash in Simulator

#83

Post by WooShoa »

krn wrote: post #11

There are also issues with 737 NG[1]: > At least three Ryanair Boeing 737s have been grounded due to cracks between the wing and fuselage but this was not disclosed to the public, the Guardian can reveal. > The budget Irish airline is the latest to be affected by faults in the “pickle fork” structure, which has sparked an urgent grounding of 50 planes globally since 3 October. [1] https://www.theguardian.com/business…

That is not nearly the same issue. It is a relatively tiny few airplanes with very high numbers of legs, i.e., landings, which is the most likely culprit (exacerbated by hard landings of inexperienced, low cost pilots). And most of the grounded planes seem to just meet lowered inspection thresholds; many of which will simply enter service again after inspection.

Re: Delays in Boeing Max Return Began with Near-Crash in Simulator

#84

Post by Xixi »

xvf22 wrote: post #41
anticensor wrote: post #38

Earlier quoted context omitted.

Slightly redesigning the wings and fitting 4 engines which are sized similarly to ones in 737-400, instead of 2 large engines might solve the problem.

Four engines are generally way more inefficient than two big ones. That's why they're being phased out. A340,B747,A380, BA146, etc.

Contrary to popular belief, quad engine planes are not inefficient [1], at least not in terms of fuel consumption (we are talking 1% to 2% difference). In terms of dispatch reliability however I think they are doing somewhat worse than twins, as they are more likely to have one engine out of service. And it not a small problem: a plane flying revenue passengers is an asset, but a plane not flying is a liability.

At least two of the planes you list are not being phased out because they were quads. The A340-300 was doing very well against the 777, however the A340-600 did very poorly against the 777-300ER. This is because the frame was too long and narrow, requiring extra reinforcement not to bend, thus ending up much heavier than the frame of the 777. The frame itself was grossly overweight, the extra engines were a rounding error.

The A380 was (and still is) extremely efficient (in terms of fuel burn per seat, at equivalent seating density), with a fuel consumption similar if not better than that of 787s or A350s, despite engines one generation older. It is, however, way way too big. In the end flying empty seats is very inefficient. But that has little to do with having 4 engines instead of 2.

The re-engined 777-9 will certainly be the most efficient plane flying when it is launched in 2021. Yet sales are lacking. It may, like the A380, turned out to be too big.

[1] https://leehamnews.com/2015/12/11/bjorns-corner-twins-or-qua...

Re: Delays in Boeing Max Return Began with Near-Crash in Simulator

#85

Post by linuxftw »

phicoh wrote: post #75
linuxftw wrote: post #67

Earlier quoted context omitted.

> In effect you are stating that you understand better than the hundreds of engineers involved with this project why these design trade-offs were made. We don't know that any engineers approved this design. It could have been completely compartmentalized and approved by management only. We'll never know what the engineers said until there's a complete investigation and the engineers are subpoenaed. Here's what we kno…

I think the key thing is how the MCAS added new failure modes that the pilots where not briefed about. There should be way more strict user interface requirements. Including how humans are supposed to react to failures and whether that makes sense from human psychology point of view If the MCAS had informed pilots of a potential sensor failure, then there would have been a very good chance that the pilots would have…

> If the MCAS had informed pilots of a potential sensor failure, then there would have been a very good chance that the pilots would have been able to land the planes safely.

Perhaps on the two crashes. We don't have any data on successful landings with MCAS disabled in very adverse flying conditions.

What if the plane is unsafe to fly without proper MCAS operation?

There should be a test that results in a plane crash with 50% of the simulations with MCAS behaving properly (IE, extreme weather, low fuel, land or die). Now during that same simulation, disable MCAS randomly. Also, there seems to be potential for the MCAS to come in and out based on disagreement (loose sensor wiring, etc), and see what the crash rate is for intermittent MCAS failures.

It's clear Boeing didn't do any of this kind of testing because they would have easily caught the failure modes that caused the plane to nose-dive into the ground. Completely predictable based on the behavior of the system.

Re: Delays in Boeing Max Return Began with Near-Crash in Simulator

#86

Post by WooShoa »

speeder wrote: post #17
MobileVet wrote: post #4

Considering that MCAS is an added ‘feature’ to avoid stall, you would think they could just remove it and be done. After all, it wasn’t part of the original 737. Sadly, from my limited understanding, due to the engine location change on the airframe, the plane naturally pitches up... making it necessary. One thing seems clear to the external observer, this is a 737 in name only.

Well, it IS a 737, that is part of the problem. The 737 has a feature almost no other new plane have: you can order it with a internal staircase so people can leave the plane without a specialized airport terminal. This feature requires the plane to keep its current overall shape, otherwise the staircase thingy would not work. So to keep this feature, while putting a bigger engine on the plane, they had to move the e…

The Homer car comes to mind whenever these kinds of convoluted and unchecked engineering adventures have the light shone on them.

Re: Delays in Boeing Max Return Began with Near-Crash in Simulator

#88

Post by 0xffff2 »

imglorp wrote: post #44
xvf22 wrote: post #39

Earlier quoted context omitted.

A split brain in a plane is a bit of a nightmare. I'm not sure how they can work around it with just two computers.

Big "disagree" alarm for the pilots and let them decide to keep either computer or go direct. Airbus has the concept of flight control laws, surfaced and changeable by the wet backups. http://www.airbusdriver.net/airbus_fltlaws.htm

>go direct

That's not really a thing in modern airliners. The computer is still heavily involved even when hand-flying the plane.

Re: Delays in Boeing Max Return Began with Near-Crash in Simulator

#89

Post by Robotbeat »

danso wrote: post #10

FWIW, the near-crash in the simulator was apparently not directly related to MCAS, but occurred when Boeing "simulated what would happen if gamma rays from space scrambled data in the plane’s flight-control computers." > In one scenario, the plane aggressively dove in a way that mimicked what happened in the crashes on the grounded jetliner, the people said. While such a failure had never occurred in the 737’s histor…

Airplanes are flying above the vast majority of the atmosphere, which provides a majority of the shielding for us on Earth. It's a real concern, and extensive care is taken when designing spacecraft electronics for exactly this reason.

Re: Delays in Boeing Max Return Began with Near-Crash in Simulator

#90

Post by vesinisa »

jackhack wrote: post #53
akersten wrote: post #2

These should not fly for a decade. They're rewriting the avionics from scratch. This should require a years-long process of testing, external auditing, and approvals. I'd even go so far as to say in flight, we should require competitor review. That's right, no trade secrets. If you want your Hello World up in the air, you better let your competitor vet the source code. This is an engineering boondoggle and an embarra…

>>Software does not need to be this complicated. >>Design a damned airframe that's airworthy without needing stabilization hacks. In effect you are stating that you understand better than the hundreds of engineers involved with this project why these design trade-offs were made. Careful with that line of thinking. You're nearly guaranteed to be wrong. There are a host of reasons for the design in place: Efficiency, e…

The reason for the MCAS hack was not any engineering wisdom but simply allowing them to build a completely different plane that they could claim was in fact the very same plane, and then sell it to airlines as such. While the aircraft manufacturing industry was decades ago heavily safety-focused, this oversight was possible because the FAA has resigned its regulatory powers to the industry's own "self-regulation".

When the purported self-regulation of a stock market company stands between making large profits, guess which one budges?

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