# Boeing - Design Issues...

Discussion in 'Rules and Regulations / Flight Safety / Better Pil' started by TXFlyGuy, Apr 11, 2019.

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1. Apr 18, 2019

### mcrae0104

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SVSUSteve, your timing is off. The day for dead guys to make a comeback isn't until Sunday.

Welcome back regardless.

2. Apr 18, 2019

### larr

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This is from the NTSB report on the Aloha incident:
NTSB assigned a high degree of responsibility to the FAA for lax oversight and generalized bumbling. Somehow, that gets left out of the usual discussions about this incident.

Claiming that the "real reason" is being hushed up is peculiar. The FAA just ignores NTSB reports it doesn't like.

3. Apr 19, 2019

### flyboy2160

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Right, it wasn't her call. Moreover, if those two 'buyers' had bothered to visit real airplane manufacturing facilities before everyone went CAD bonkers, they would have seen zillions of really good airplanes being built by hand using the type of 'infamous' fixturing shown in the 'horrifying' photos. As a CAD guy, I fully get the desire for CNC accuracy. But lots of great planes were built using hard fixtures. Yes, you had to fiddle some stuff, but that didn't make the parts not airworthy - unlike what these buyers turned engineering 'experts' are claiming. Looks like too much sensational reporting without looking at the actual shop floor disposition paperwork.

Last edited: Apr 19, 2019
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4. Apr 20, 2019

### Bill-Higdon

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Boing isn't the only one flash.avweb.com/avwebflash/news/AOA-Sensor-Malfunction-Prompts-Vision-Jet-Emergency-AD-232666-1.html

5. Apr 21, 2019

### Bill-Higdon

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This is from Slash.net https://tech.slashdot.org/story/19/...37-max-disaster-looks-to-a-software-developer
Slashdot reader omfglearntoplay shared this article from IEEE's Spectrum. In "How the Boeing 737 Max Disaster Looks to a Software Developer," pilot (and software executive) Gregory Travis argues Boeing tried to avoid costly hardware changes to their 737s with a flawed software fix -- specifically, the Maneuvering Characteristics Augmentation System (or MCAS): It is astounding that no one who wrote the MCAS software for the 737 Max seems even to have raised the possibility of using multiple inputs, including the opposite angle-of-attack sensor, in the computer's determination of an impending stall. As a lifetime member of the software development fraternity, I don't know what toxic combination of inexperience, hubris, or lack of cultural understanding led to this mistake. But I do know that it's indicative of a much deeper problem. The people who wrote the code for the original MCAS system were obviously terribly far out of their league and did not know it.

So Boeing produced a dynamically unstable airframe, the 737 Max. That is big strike No. 1. Boeing then tried to mask the 737's dynamic instability with a software system. Big strike No. 2. Finally, the software relied on systems known for their propensity to fail (angle-of-attack indicators) and did not appear to include even rudimentary provisions to cross-check the outputs of the angle-of-attack sensor against other sensors, or even the other angle-of-attack sensor. Big strike No. 3... None of the above should have passed muster. None of the above should have passed the "OK" pencil of the most junior engineering staff... That's not a big strike. That's a political, social, economic, and technical sin...

The 737 Max saga teaches us not only about the limits of technology and the risks of complexity, it teaches us about our real priorities. Today, safety doesn't come first -- money comes first, and safety's only utility in that regard is in helping to keep the money coming. The problem is getting worse because our devices are increasingly dominated by something that's all too easy to manipulate: software.... I believe the relative ease -- not to mention the lack of tangible cost -- of software updates has created a cultural laziness within the software engineering community. Moreover, because more and more of the hardware that we create is monitored and controlled by software, that cultural laziness is now creeping into hardware engineering -- like building airliners. Less thought is now given to getting a design correct and simple up front because it's so easy to fix what you didn't get right later.

The article also points out that "not letting the pilot regain control by pulling back on the column was an explicit design decision. Because if the pilots could pull up the nose when MCAS said it should go down, why have MCAS at all?

"MCAS is implemented in the flight management computer, even at times when the autopilot is turned off, when the pilots think they are flying the plane."

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6. Apr 21, 2019

### Vigilant1

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Seems the author is just regurgitating the existing talking points, with some added hand waiving and bluster. Does not appear to be very familiar with the details of the issue. Who would write "angle of attack indicator" when they are clearly talking about angle of attack sensors? Who would write this:
"Even at times the autopilot is off?" The MCAS is active only at times the autopilot is off.

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7. Apr 21, 2019

### Wanttaja

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Hey, Greg Travis is still around. That name should be familiar to the old USENETers out there....

Ron Wanttaja

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8. Apr 21, 2019

### TXFlyGuy

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Most of the points above are valid. Even if it is done with a bit of "hand waving", still shows the areas where Boeing screwed the pooch.

I have pointed out previously that safety takes a back seat to the bottom line dollar cost. If you can get the airline management team behind closed doors, and off the record, they will tell you that "X" number of fatalities are acceptable within the total realm of the worldwide operation. It is a purely cost driven issue.

Boeing has been proud of the fact that they (until now) have always allowed the pilot to be the final authority in the actual flying of the aircraft. Unlike Airbus, which relies on automation and software to be the final authority.

How many of you recall the NW Airlines Chief Pilots that took an A-320 into the trees? Plus there are many other stories about the Airbus, not doing what the pilots intended.

It looks like Boeing is creeping ever closer to the Airbus philosophy, all in the name of saving some \$.

9. Apr 21, 2019

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Another article alleging Boeing's lack of safety priorities: https://www.msn.com/en-us/news/us/c...-to-a-second-boeing-jet/ar-BBW8hXN?li=BBnb7Kz

10. Apr 21, 2019

### BBerson

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I watched another Smithsonian Air Disasters episode last night about an Airbus 330 that pitched down so hard several passengers were severely injured on the way to Perth Australia. Turned out one flight computer was feeding bad angle of attack data. The captain got it down after two severe negative g pitch downs. Investigators found two other airplanes with same defect.
The pilot doesn't get last say anymore.

11. Apr 21, 2019

### Kyle Boatright

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That one feels like a pile-on. You could survey any manufacturer's employees or ex-employees in any field and find the same complaints. You can also find instances of left behind tools and debris in virtually every aircraft manufacturer's fleet. The stuff they found when they did the post-fire inspection of Apollo 1 was telling in that a space capsule gets a lot more attention than an airplane and they found plenty of swarf, damaged wiring, and leftover tools despite all of the extra attention.

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12. Apr 21, 2019

### TXFlyGuy

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Just like a friend always told me..."Don't ask a Mercedes-Benz owner what they think about their car. Always ask a former M-B owner to get the truth."

Certainly you can find examples of disgruntled employees at every company, Boeing included. But how many times have unhappy employees been associated with the grounding of an entire fleet of aircraft?

13. Apr 21, 2019

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I can maybe see dropping a wrench and not noticing it....but a ladder!

14. Apr 21, 2019

### Himat

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A lot of great planes have been built using hard fixtures. There is a catch, they were designed to be manufactured that way. With CAD and CNC accuracy it is possible to optimise the design to these limits. That is the FOS, factor of safety, is reduced to be just what is needed with the high accuracy in manufacturing. That saves airplane weight that can be cashed in on the bottom line. Airbus did test one wing to failure and was very pleased when it failed at 99% of designed failure load. That told then that the wing was just strong enough.

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15. Apr 22, 2019

### TXFlyGuy

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We have all seen the videos of Boeing testing the wings to the max limit, up to and including wing failure. I'm not sure at what load factor the wing actually snapped, but I'll bet you a case of your favorite beer that is was well beyond the design limit.

16. Apr 22, 2019

### Voidhawk9

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The 777 wing was 151% of design limit load if I recall correctly. It was intended to break at 150%. Not bad!
AFAIK they never tested 787 wings to breaking point, though they did bend them a lot!

17. Apr 22, 2019

### TXFlyGuy

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Just another reason why I like the 777!

18. Apr 22, 2019

### Workhorse

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19. Apr 23, 2019

### Himat

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Not bad, a question is then if the parts were at their max, min or random distributed tolerances? Put a lot of effort into calculation and selection of part and the chosen set could produce the strongest wing, a more random selection may produce a lighter wing that did break at 149,5% of ultimate load.

Next, if such a close match could be shown to be predictable and consistent in production I guess Boing and others would start to argue to reduce the FOS. After all part of the reasoning behind having a FOS is to have an allowance for production tolerances.

20. Apr 25, 2019

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