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U.S. FAA proposes requiring key Boeing 737 MAX design changes

reuters.com

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Re: U.S. FAA proposes requiring key Boeing 737 MAX design changes

#221

Post by tankenmate »

phire wrote: post #146
simion314 wrote: post #55

Earlier quoted context omitted.

Do we know or is a reason to believe that FAA checked anything else then the MCAS and the systems related in the crashes? The MAX has probably many differences because is larger so all the new stuff should be put under the microscope since you can't trust the previous tests, measurements or decisions, Boeing guys were proud on how they mind tricked the FAA guys so FAA should now re=review everything then you can be 1…

The European equivalent of the FAA, the EASA are double checking all of the FAAs working here. The FAA are highly motivated to get everything correct this time in order to repair their reputation (which was tarnished by their original MAX approval). It would be highly embarrassing for if the EASA find anything the FAA missed.

The EASA made some noises about requiring 3 AoA sensors (which all Airbus aircraft have) as opposed the the MAX's current 2 (most newer Boeing aircraft also have 3). There was also some talk about replacing the 3rd hardware AoA sensor with a virtual sensor (maybe an infrared horizon sensor based AoA indicator which would be much easier to add to the aircraft).

Re: U.S. FAA proposes requiring key Boeing 737 MAX design changes

#222

Post by _ph_ »

henryfjordan wrote: post #7
zaroth wrote: post #3

https://www.faa.gov/news/media/attachments/19_035n-R3-8-3-20... > "To address the unsafe condition, the FAA proposes to require four design changes: (1) installing updated flight control software (with new control laws) for the FCC operational program software (OPS), (2) installing updated MDS display processing computer (DPC) software to generate an AOA disagree alert, (3) revising certain AFM flightcrew operating p…

> disable MCAS for the remainder of the flight. My understanding is that the MCAS or something equivalent is necessary on the 737 MAX because the engines sit lower than they really should and the forward propulsion creates torque that raises the nose of the plane. Something needs to counteract that force. If the MCAS is disabled, is the pilot able to trim the airplane manually similar to how MCAS works? Or will they…

MCAS is only needed in situations with a very high angle of attack, that is a very steep climb which should not happen in normal flight situations. For example, MCAS is completely deactivated, if the flaps are extended. So unless you get into the steep angles, a 737 MAX with MCAS disabled, wouldn't even feel different in flying.

Re: U.S. FAA proposes requiring key Boeing 737 MAX design changes

#223

Post by _ph_ »

MaxBarraclough wrote: post #207
holler wrote: post #47

Earlier quoted context omitted.

> seems to amount to about 20 lines of code it's sobering to think that 20 lines of code could potentially have saved 346 lives :/

That doesn't sound right. If I understand correctly, the crashes were not due to a programmer making a mistake in a few lines of code. They were due to inadequate sensor redundancy, inadequate pilot retraining, and possibly a missing warning light [0] (the fault still lying with Boeing on all three points). At no point did the behaviour of the MCAS software deviate from its specification. [0] https://www.nytimes.com/…

Deactivating MCAS on AOA disagree would have prevented both crashes. But yes, the program behaved to spec, so strictly speaking it is not a programmer error but a spec problem.

Re: U.S. FAA proposes requiring key Boeing 737 MAX design changes

#224

Post by tankenmate »

tankenmate wrote: post #221
phire wrote: post #146

Earlier quoted context omitted.

The European equivalent of the FAA, the EASA are double checking all of the FAAs working here. The FAA are highly motivated to get everything correct this time in order to repair their reputation (which was tarnished by their original MAX approval). It would be highly embarrassing for if the EASA find anything the FAA missed.

The EASA made some noises about requiring 3 AoA sensors (which all Airbus aircraft have) as opposed the the MAX's current 2 (most newer Boeing aircraft also have 3). There was also some talk about replacing the 3rd hardware AoA sensor with a virtual sensor (maybe an infrared horizon sensor based AoA indicator which would be much easier to add to the aircraft).

I found the article I read about the 3rd AoA sensor.

https://www.seattletimes.com/business/boeing-aerospace/europ...

Re: U.S. FAA proposes requiring key Boeing 737 MAX design changes

#225

Post by _ph_ »

bedhead wrote: post #13

Can we just scrap this thing and move on already? Isn’t all of this back-and-forth alone evidence that this thing shouldn’t be flying?? It’s over, Boeing, you lose.

The 737 MAX with the MCAS fix is as secure as any 737 out there. Perhaps even more so due to having new engines, all of them being new air frames and because to my understanding in the review of the software they found and fixed another issue which always has been present.

One can certainly argue, that Boeing should have invested into a true 737 successor a long time ago instead of updating the old design, especially with all the restrictions of keeping the same type rating.

The problem is, this hasn't happened. Assuming air travel bounces back to pre-Covid levels, there is a huge demand for 737-class airplanes. Like thousands. Creating a replacement (which Boeing really should start like yesterday) will take about 10 years, you don't want to rush that, if you don't want to create an even larger security problem (just look to the 787 for initial problems and ongoing reports about manufacturing issues). So for the next 10 years, the option is either to fly the 737 MAX, fly much less or with aging 737 air frames from the pre-MAX times.

Re: U.S. FAA proposes requiring key Boeing 737 MAX design changes

#226

Post by ummonk »

joshcain wrote: post #141
rsynnott wrote: post #100

Earlier quoted context omitted.

Most airlines only use one manufacturer for this size class; it’ll be 737-XXXs, or a32Xs, but rarely both. So just choose an appropriate airline. Not always an option, of course, but on the biggest routes it generally is.

Many airlines use both Airbus and Boeing within the same size class. American, United, and Delta all operate both 737s and A320-class planes.

JetBlue is only A320/321.

Re: U.S. FAA proposes requiring key Boeing 737 MAX design changes

#227

Post by stevehawk »

dharmab wrote: post #22
stevehawk wrote: post #20

Earlier quoted context omitted.

I would. I get it that Boeing messed up the first time, but this was always a failure that was preventable with proper pilot instruction and awareness. Even if they didn't fix the software I couldn't imagine a 737MAX pilot not being aware of this. People still drive Tesla's using autopilot and they drive head on into barriers on the highway or under trailers and decapitate people.

You have more confidence in the plane than the people who designed and built it. https://www.nytimes.com/2020/01/09/business/boeing-737-messa...

To my knowledge, we don't actually know that. None of the emails I've seen refer to anyone's title or name. For all I know it's a janitor who heard rumors around a water cooler.

Re: U.S. FAA proposes requiring key Boeing 737 MAX design changes

#228

Post by ryndbfsrw »

mathogre wrote: post #151

That's bullshit. The MAX aircraft are not the same as the earlier 737 line. These should be completely certified as new aircraft, and my guess is they would fail real certification. The required "design changes" are nothing. Not only would I not want to fly on one of the MAX aircraft, I wouldn't want to live underneath a procedure - departure, airway, approach - used by a MAX. Go for it. Let them fly. 'Boeing has bui…

Add to this the meta-problem this creates. Right now, there's trust in the industry to not cut corners which is one of the reasons so many choose to fly. If that trust erodes (even slightly) it is difficult to gauge what the impact would be. I remember an AA exec saying they make their profit on the last 4/5 people per flight. Combo of thin margins, high gearing and the industry is exposed to even small shocks in demand.

Re: U.S. FAA proposes requiring key Boeing 737 MAX design changes

#229

Post by ummonk »

morganw wrote: post #90
xvf22 wrote: post #46

Earlier quoted context omitted.

Given that the 737 isn't fly by wire the forces needed to operate the controls is something critical that a home sim isn't going to be able to model.

Watch how much effort it takes to adjust trim with the motors disabled https://youtu.be/xixM_cwSLcQ?t=1106 It's good that MCAS will now disable itself without having to disable the trim motors completely. I wish they'd just taken the hit on a new type rating and given up on MCAS completely after the failures. Perhaps new 737 pilots could get training on NG and MAX at the same time? One thing I'm not seeing much discu…

The type rating is not the reason for MCAS. MCAS is there to make the aircraft satisfy certain stability requirements mandated for all planes by the FAA to prevent an inadvertent stall.

So even with a new type rating, MCAS would still be needed unless the airframe were massively redesigned.

Re: U.S. FAA proposes requiring key Boeing 737 MAX design changes

#230

Post by acqq »

bkor wrote: post #192
WalterBright wrote: post #166

Earlier quoted context omitted.

The LA pilots worked the problem for 5 minutes, the EA 2 minutes. Quite a bit more than seconds. Frankly, I'm baffled by the EA pilots. If I was a MAX pilot, and I received an EMERGENCY AIRWORTHINESS DIRECTIVE about how to not crash like LA pilots, it's my job to read, understand, and remember those instructions. And not just my job, it'd save my own life, too. It's not like it's complicated, either. Two simple steps…

A crash is not due to one cause. Multiple things have to fail for this to be a problem. Blaming pilots is way too simplistic. The design of those warnings were highly confusing and overwhelming. Saying "oh, just have better pilots" it NOT good enough. It should be as per the Swiss cheese theory where multiple things should fail before there's a problem. Further, not hide things like MCAS, downplay the need for additi…

> it was the pilots not reading a message.

It was that the message (see the whole, the link was quoted) definitely wasn't clear. It has multiple weasel words and it is far from a clear and actionable sequence checklist for the exact condition in which two planes were put due to the MCAS. Only with the hindsight of knowing how two accidents developed and the independent pilots trying to reconstruct on the simulators these events it can be claimed that that formulation described something usable. Just with the pilots "reading it" at that time and even having it in front of them at the moment of the accident, without any special training for that situation (where the plane multiple times "undoes" the actions of the pilot, orienting the plane toward ground as the plane is still flying low) it's still improbable that the accident wouldn't happen.

Note: It's Boeing who insisted that the training for MCAS is not needed.

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