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FAA Finds New Risk on 737 Max, Orders Boeing to Make Changes

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Re: FAA Finds New Risk on 737 Max, Orders Boeing to Make Changes

#171

Post by Animats »

jamesharding wrote: post #168
Animats wrote: post #161

Earlier quoted context omitted.

Basic rudimentary 'stick and rudder' flying skills was a big factor in AF447's crash. All old school pilots know that when you aircraft is in a nose high stall condition, you never keep pulling back on the stick, but instead push it forwards to lower the nose and get the wings flying again. Except on an Airbus. If the plane is in "normal law", it won't go into a stall condition. Here's the Airbus training video.[1] N…

The engines in the MAX are still producing thrust below the centre of mass of the plane...how would this produce a nose down pitch at TOGA thrust?

Sorry, backwards.

Re: FAA Finds New Risk on 737 Max, Orders Boeing to Make Changes

#172

Post by nemetroid »

jbigelow76 wrote: post #100
jussij wrote: post #41

The FAA suffered a major loss of credibility in their handling of the first round of testing/accreditation of the MAX. The FAA can't afford another stuff up this second time around and as such I suspect they will be checking every aspect of the plane in very fine detail. That could spell more trouble for Boeing.

The FAA suffered a major loss of credibility in their handling of the first round of testing/accreditation of the MAX. The FAA can't afford another stuff up this second time... Because I'll just check with the next air transit regulatory body right?

The FAA and EASA have an agreement of trust regarding type certificates issued by the other party[0] (i.e., if the FAA certifies an aircraft, EASA will allow that aircraft to fly in Europe without performing its own technical certification process).

This agreement only works as long as both parties trust each other's certification process.

0: https://www.easa.europa.eu/document-library/bilateral-agreem...

Re: FAA Finds New Risk on 737 Max, Orders Boeing to Make Changes

#173

Post by nemetroid »

jbigelow76 wrote: post #119
chrisbolt wrote: post #108

Earlier quoted context omitted.

Like the European Aviation Safety Agency?

So the FAA says "this is fucked" and and the EASA says "they're all good bro"[1], who do you side with? [1] feel free to flip flop regulatory agencies if you so desire.

Depends on where you want to fly.

Re: FAA Finds New Risk on 737 Max, Orders Boeing to Make Changes

#174

Post by TazeTSchnitzel »

bjourne wrote: post #133

Since this thread is already full of armchair airplane engineers opinions about the root cause, I'll add mine too: Never ever write new software under the condition that it must work EXACTLY as old software. It can't be done and you'll always miss something. Case in point: Wine. They've been at it for years and the emulation layer is still far from perfect. It works 99% of the time which is good enough for games, but…

Wine is not a good example. They don't have access to the source code of the original system, and they haven't had the resources to cover the entire footprint of the Windows APIs.

Re: FAA Finds New Risk on 737 Max, Orders Boeing to Make Changes

#175

Post by dandare »

As a web/game developer, one thing I never understood is the alleged complexity of these control systems. There is no image/voice recognition, no graphics engine, no rocket science. What are they even doing? Or is it all a big lie?

Lines of code, from the internet[1]: Pacemaker: 100k Boeing 787: 5M Chevy Volt: 10M Modern car: 100M

[1] https://www.visualcapitalist.com/millions-lines-of-code/

Re: FAA Finds New Risk on 737 Max, Orders Boeing to Make Changes

#176

Post by mikekchar »

firethief wrote: post #164
mikekchar wrote: post #158

Earlier quoted context omitted.

Fukushima survived the earthquake and even survived the tsunami. The generator got wiped out, but even that wasn't what ultimately led to the disaster. It was that the battery backup eventually ran out of power (not unexpected) and the connectors for recharging it were old and of a format that isn't used any more. There was no way of recharging the battery backup and so the pumps eventually failed. It's one of those…

> since the emergency system is not used normally, it's easy to overlook a critical problem. This is a such an important antipattern when robustness is a goal.

Totally agree. Done it myself more times than I care to admit. One small quibble, if I may. Originally "antipattern" used to mean something that looks like a good design pattern, but will actually bite you in the end if you used it as intended. This is not so much an anti-pattern as it is an unfortunate reality (you have to maintain compatibility with external interfaces for the length of the project). How much bit rot have I seen in my career?

Re: FAA Finds New Risk on 737 Max, Orders Boeing to Make Changes

#177

Post by baby »

dandare wrote: post #175

As a web/game developer, one thing I never understood is the alleged complexity of these control systems. There is no image/voice recognition, no graphics engine, no rocket science. What are they even doing? Or is it all a big lie? Lines of code, from the internet[1]: Pacemaker: 100k Boeing 787: 5M Chevy Volt: 10M Modern car: 100M [1] https://www.visualcapitalist.com/millions-lines-of-code/

Why I can’t understand is why audio is still shit, and why they can’t get immediate live help from some 24/7 support. Don’t we have the technology?

Re: FAA Finds New Risk on 737 Max, Orders Boeing to Make Changes

#178

Post by 238475235243 »

dandare wrote: post #175

As a web/game developer, one thing I never understood is the alleged complexity of these control systems. There is no image/voice recognition, no graphics engine, no rocket science. What are they even doing? Or is it all a big lie? Lines of code, from the internet[1]: Pacemaker: 100k Boeing 787: 5M Chevy Volt: 10M Modern car: 100M [1] https://www.visualcapitalist.com/millions-lines-of-code/

There's a number of pieces:

* Writing everything three times for three different computers with three different architectures in three different ways (e.g. numerical vs symbolic integration)

* Using obsolete programming languages for the same reasons doctors use latin

* Has to be usable by poorly trained pilots, while tired, on the other side of the planet in complete darkness with half the systems failing.

* Nobody dies if you web/game crashes. The plane has to still be flyable in unimaginably bad conditions like a total engine loss by deploying a windmill (ram air turbine), therefore every scenario is accounted for.

Caveat is we usually find new scenarios by crashing planes, not by thinking about them first. Kind of a definitional thing: if you'd thought of it, it wouldn't have crashed.

Re: FAA Finds New Risk on 737 Max, Orders Boeing to Make Changes

#179

Post by jacquesgt »

jussij wrote: post #135
jacquesgt wrote: post #81

Earlier quoted context omitted.

AF 447 wasn’t all that different from this situation. One of the co-pilots was trying to pitch the nose down to recover from the stall. The other was panicking and trying to pitch up. The plane averaged their inputs, without giving feedback via the stick that this was happening. It wasn’t until very late in the flight that they figured out what was happening, and then it was too late to recover. Obviously there was s…

I don't the flight control was averaging the pilot inputs. From this link: https://en.wikipedia.org/wiki/Air_France_Flight_447#Human_fa... In April 2012 in The Daily Telegraph, British journalist Nick Ross published a comparison of Airbus and Boeing flight controls; unlike the control yoke used on Boeing flight decks, the Airbus side stick controls give little visual feedback and no sensory or tactile feedback to the…

You may be right about the averaging. From rereading the accident report, the Pilot Flying took back control of the plane after the Pilot Not Flying engaged his controls and tried to pitch down.

But, it’s the same basic idea. The PNF thought he’d gotten control of the plane, and didn’t understand why his input wasn’t having an effect. He didn’t get feedback from the stick telling him a different input was being honored. And neither pilot appears to have been fully aware that they were in a flight control mode where there was a risk of stalling. The PF especially never seemed to have made that connection, and the PNF took a fairly long time to call it out. As a result, the PF may not have been aware that he needed to actively keep the angle of attack inside the flight envelope.

So, PNF tries to pitch down, but isn’t aware the plane got put back into a mode where he isn’t in control. PF is pitching up, but isn’t aware the plane switched to a mode where this could lead to a stall. That’s the similarity I was getting at.

Re: FAA Finds New Risk on 737 Max, Orders Boeing to Make Changes

#180

Post by pvg »

blackflame7000 wrote: post #163
pvg wrote: post #101

Earlier quoted context omitted.

Both accidents attributed to rudder hardover took place before the 737 NG first flew in 1997.

There were a lot more than just 2 rudder incidents. USAir Flight 427 United Airlines Flight 585 Eastwind Airlines Flight 517 Silkair Flight 185 Copa Airlines Flight 201 China Southern Airlines Flight 3943 MetroJet Flight 2710

I mean. I am going by wikipedia here but most of the things you've said in this subthread seem to be inaccurate. It wasn't the original 737. It wasn't the NG. And most of the accidents you've listed were not caused by that particular rudder design problem (as far as I can tell, 3 were, maybe?). You keep adding new inaccurate things without the slightest acknowledgement you might have misremembered or misstated something before.
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