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How Boeing, FAA certified the suspect 737 MAX flight control system

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Re: How Boeing, FAA certified the suspect 737 MAX flight control system

#101

Post by masklinn »

Merrill wrote: post #93

How did Boeing decide to kill the 757 and to continually delay the "New Midsize Airplane", and to progressively extend and modify the 737 until it reached 757 size in the 737 MAX 9? I would bet good money that there is a wonderful book to be written about competing design teams, rival marketing plans, and mahogany row politics at Boeing about events resulting in the MAX kludge. Also: "An airline pilot reveals why a p…

> How did Boeing decide to kill the 757 and to continually delay the "New Midsize Airplane", and to progressively extend and modify the 737 until it reached 757 size in the 737 MAX 9?

> Southwest Airlines has only operated Boeing 737 jetliner models, except for a period from 1979 to 1987

I expect that sort of things was part of the decision. Even more so as Boeing never really try to unify their offering and provide airbus-style CCQ[0][1] so there is a very strong incentive & pressure to update frames and keep them in the same rating to avoid crew retraining costs.

[0] moving from an A320 to an A380 can take as little as 15 days, other moves are much shorter (down to 2 days CCQ for — I believe — moving between the A330 and the A340)

[1] boeing does have some common type rating courses but only between a few pairs e.g. between the 757 and 767, or from the 777 to the 787

Re: How Boeing, FAA certified the suspect 737 MAX flight control system

#102

Post by cesarb »

trt808 wrote: post #41

So what's the most likely outcome for all the grounded planes at this point? As someone who has some fear of flying I'll definitely make sure none of my trips include a 737 max in the future, no matter how many patches or upgrades boeing releases

IMO, the most likely outcome is: initially, they'll stay grounded until the flight recorders from the latest crash are analyzed, and it's confirmed that it's probably the same or a related cause (if the cause was unrelated, they might be allowed to resume flying earlier). Then a fix to the software will be developed, taking into account the preliminary results of the investigation; Boeing has a head start here, since they started developing the fix after the previous crash. After it's validated that the fixed software would have prevented both accidents, the authorities will change the rule from "all planes of this type are grounded" to "all planes of this type are grounded, unless they have software version at least X.YY on that subsystem, or are flying with no passengers to a maintenance facility to install that software version". And then the companies which own these planes will install the fixed software, and normal flying will resume.

Re: How Boeing, FAA certified the suspect 737 MAX flight control system

#103

Post by organsnyder »

stcredzero wrote: post #22

There is a big difference between how you behave when you're calm, vs how you behave when you're under stress. Basically, you start hitting sub-sentient "defaults." You default to your training. You default to inherited flight or fight behaviors. Emergency procedures and training need to be designed with this in mind, or they will fail. (Presentation preparation is like this. My last presentation failed because by se…

I had an organ teacher that (gently) reprimanded me at a lesson after I exclaimed, "But it went great while I was practicing!" after making some mistakes while playing through a piece. Yes, I might have learned it to the point that I could play it well under no pressure, but I hadn't learned it to the point that I could do the same during a lesson—let alone a performance.

Even with pilots aware of the MCAS system, I don't see how anything short of simulator time can really make these planes safe.

Re: How Boeing, FAA certified the suspect 737 MAX flight control system

#104

Post by briandear »

wnevets wrote: post #30

>FAA for pushing engineers to 'delegate' reviews of certain components back to Boeing themselves. How much more proof do we need as a society that self regulation is a fool's errand?

How many 737s crashed while under FAA jurisdiction? The US has had one commercial airliner fatality since 2009, so it would seem that the FAA is doing something right. Maybe Kenya and Indonesia need some improvements?

Re: How Boeing, FAA certified the suspect 737 MAX flight control system

#105

Post by DiffEq »

outworlder wrote: post #83
ajross wrote: post #55

Earlier quoted context omitted.

Yeah. As much blame as Boeing and the FAA certification process seems to deserve here, it's worth pointing out how much of the cascade of failures is in the airlines and cockpits too. I mean, yes, the trim system was being driven by input from a single nonredundant sensor, which is a violation of the kind of engineering for failure process that airliners should be designed in. But at the same time that trim system is…

> But at the same time that trim system is, by design, not strong enough to overpower pilot input to the other control surfaces. That is incorrect for the 737 and many airliners. Elevator input is way less strong than trim. Trim moves the entire surface, not just the elevator control surface. I had the same misconception, my brain was translating GA aircraft knowledge to airliners.

The GA Aircraft; Cessna 182B has Stab trim.

Re: How Boeing, FAA certified the suspect 737 MAX flight control system

#106

Post by kevin_b_er »

MockObject wrote: post #64
wnevets wrote: post #61

Earlier quoted context omitted.

That is misleading at best. The FAA was instructed to let the industry to regulate itself more, a typical republican/libertarian belief. Boeing being allowed to self regulated created this mess. https://www.forbes.com/sites/marisagarcia/2019/03/18/did-tru... >Still, the US DOT mandated that the FAA begin the process of review to reduce regulations. The FAA assigned this task to ARAC, effectively putting the question…

But an inherent bug of government regulation is that it's always vulnerable to lobbying like you cited. So it's still a failure of regulation, except one that is permanent and unsurprising.

Our government is quite vulnerable to corruption by the rich and powerful. You will watch some propose that, since the rich have corrupted the governement's protections for the people, that those protections should be removed. But this is the original goal in the first place: Remove protection for the people against the abuse by the powerful.

Re: How Boeing, FAA certified the suspect 737 MAX flight control system

#107

Post by vpribish »

Since I keep seeing partially-informed comments about 737 pitch controls here's some notes and terms and links: It's not obvious, it's not simple, and other planes work in other ways - you can not just assume the 737MAX is like them.

The 737 horizontal tail externally looks like 3 moving parts:front-to-back (and large to small) is: Stabilizer : Elevator : Balance Tab.

see here: http://www.b737.org.uk/flightcontrols.htm#Pitch

Stabilizer moves in response to trim - this is what we are mostly looking at.

Elevator moves in response to the control column.

Balance tab has several modes depending on flaps and hydraulic system health - but it mostly serves to offset aerodynamic force on the elevator in case the hydraulics fail and the elevator has to be controlled manually.

(there is one other pitch control, I learned - the spoilers on the wing can give some help in landing in case the elevator controls fail.)

There are many modes of operation and simple generalizations will not help.

Re: How Boeing, FAA certified the suspect 737 MAX flight control system

#108

Post by CharlesColeman »

MockObject wrote: post #64
wnevets wrote: post #61

Earlier quoted context omitted.

That is misleading at best. The FAA was instructed to let the industry to regulate itself more, a typical republican/libertarian belief. Boeing being allowed to self regulated created this mess. https://www.forbes.com/sites/marisagarcia/2019/03/18/did-tru... >Still, the US DOT mandated that the FAA begin the process of review to reduce regulations. The FAA assigned this task to ARAC, effectively putting the question…

But an inherent bug of government regulation is that it's always vulnerable to lobbying like you cited. So it's still a failure of regulation, except one that is permanent and unsurprising.

>> That is misleading at best. The FAA was instructed to let the industry to regulate itself more, a typical republican/libertarian belief. Boeing being allowed to self regulated created this mess.

> But an inherent bug of government regulation is that it's always vulnerable to lobbying like you cited. So it's still a failure of regulation, except one that is permanent and unsurprising.

It's a failure of regulation that the regulated would lobby to weaken regulation?

Re: How Boeing, FAA certified the suspect 737 MAX flight control system

#110

Post by racingmars »

rnbrady wrote: post #85
mimixco wrote: post #10

Notable and disturbing here is the lack of Max simulators in existence. It looks like neither Lion Air nor Ethiopian nor any US airline had access to one. Also linked in this article is the original FAA table of differences between the Max and other 737 models. It makes no metion of MCAS.

> It makes no metion of MCAS. 27 - FLIGHT CONTROLS STABILIZER TRIM: Stab Trim cutout switches panel

Not sure what the meaning of your comment is. The Stab Trim cutout switches have been in the 737, in the same place aft of the flap selector, since the original 737. These were not a new feature related to the MCAS system.
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