7 ms·

The original 737 had some early issues also. Tail rudder problems that resulted in crashes is one that comes to mind. They were fixed and now nobody thinks twic

by throwaway201103 6y ago

The original 737 had some early issues also. Tail rudder problems that resulted in crashes is one that comes to mind. They were fixed and now nobody thinks twice about flying them and their long-term safety record is excellent.

kayodelycaon 6y ago
Tail rudder problems is putting it mildly. There was malfunction with a valve that would cause the rudder to move in the opposite direction of the control inputs.
- cdolan 6y ago
  Correct. Flight 427 to Pittsburgh. My wife’s father was on the flight. The tail’s controls inverted in freezing temperatures.
  - sillysaurusx 6y ago
    Wait, what? Anyone have any more info on this? It seems completely insane for flight control inputs to invert themselves, but only in certain temperatures. I'd love to see the incident report on that... EDIT: Ah: https://en.wikipedia.org/wiki/USAir_Flight_427 https://en.wikipedia.org/wiki/USAir_Flight_427 I'm so sorry that happened to your wife's father. The accident report is here: https://www.ntsb.gov/investigations/AccidentReports/Reports/AAR9901.pdf https://www.ntsb.gov/investigations/AccidentReports/Reports/... Section 2.7.2 is interesting: 2.7.2 Unusual Attitude Training for Boeing 737 Pilots At the time of the USAir flight 427 accident, no air carrier training programs were specifically aimed at training 737 pilots to recognize and address a rudder jam or reversal. The guidance available at that time from Boeing advised pilots, as a first consideration, to maintain or regain full control of the airplane. Specifically, the guidance advised pilots to counter unwanted roll tendencies from a malfunctioning rudder with the application of up to full aileron control inputs. However, the guidance did not advise pilots that, at some airspeeds, an uncommanded full rudder input could not be successfully opposed by full wheel (aileron and spoiler) inputs and that a reduction in the airplane’s angle-of-attack could improve the effectiveness of the roll controls relative to the effectiveness of the rudder. Boeing’s guidance for relieving a jammed rudder informed pilots only that they should use maximum force to overpower the jam and specifically warned pilots against turning off flight control switches “unless the faulty control was positively identified.” No additional guidance was provided about the effects of flight control switch selections on rudder jam conditions.
    - cdolan 6y ago
      If I start reading I go for hours haha. Am I correct that it inverted/reversed?
      - sillysaurusx 6y ago
        Yes, but I'm not sure why it inverted. If you open the accident report (https://www.ntsb.gov/investigations/AccidentReports/Reports/AAR9901.pdf https://www.ntsb.gov/investigations/AccidentReports/Reports/...) and ctrl-F "rudder", you get 2,112 matches. So "reading for hours" is a distinct possibility in this case... (Oh, by the way, I didn't mean to imply you were mistaken, or anything like that. I was just so shocked that a plane's controls could invert themselves in any conceivable circumstance. Currently digging through the accident report to try to figure out what happened.) "the probable cause of the USAir flight 427 accident was a loss of control of the airplane resulting from the movement of the rudder surface to its blowdown limit. The rudder surface most likely deflected in a direction opposite to that commanded by the pilots as a result of a jam of the main rudder power control unit servo valve secondary slide to the servo valve housing offset from its neutral position and overtravel of the primary slide" Unfortunately I don't know what most of these terms mean. It sounds like it might be saying "they moved the rudder to its limit, and then it jammed at the limit; so when they tried to command the rudder to go the other way, the rudder was pointed in the opposite direction of the control inputs." But I'm really not sure.
        cdolan 6y ago
        No offense taken. I meant that if I start researching it again I’ll be up for 5 hours because of the personal ties to it. My recollection in researching this a decade ago was that the cold weather made the behavior of the rudder change (my term was invert, maybe that’s not accurate), and pilots were trying to pull up, but in fact putting the plane deeper into a nosedive. Some 25 seconds later they hit the ground at some 300-400 MPH and vaporized. The only way to have saved the plane would have been to dump the hydraulics and/or switch to a manual fly by wire mode, neither of which were a logici thing to do in the 15 seconds they had to save the flight. I’ve only flown for 20 hours in a Cessna so sorry if my terminology isn’t perfect!
bigbob2 6y ago
In that case maybe I'll give it 50 years to develop the same safety record.
Analemma_ 6y ago
The original 737 wasn't broken-by-design in the way the Max is. The Max _requires_ software kludges to paper over its deliberate mistakes; that's very different from just having a few bugs to work out in a fundamentally sound design.
- HPsquared 6y ago
  This is a bit of an urban myth that keeps flying around. The plane is perfectly stable without MCAS, but would have had different handling characteristics than the previous version. The purpose of MCAS was to modify the handling to match the previous plane, so pilots' type ratings would carry over with minimal retraining. At its heart, it was a (poorly implemented) kludge in an attempt to sidestep a lot of paperwork.
  - throwaway201103 6y ago
    You're mostly right, but it wasn't just to make it handle like the previous versions, it was to satisfy FAA certification rules on how it handled.
    - cjbprime 6y ago
      This is my understanding too, though Boeing hasn't really come out and said it definitively. Specifically: > MCAS was devised to fulfill an airworthiness certification condition in 14 CFR 25.173 and 14 CFR 25.175. In high angle-of-attack (AoA) flight configuration, it is required that stick force/g (the stick force necessary to produce (hold) an incremental normal acceleration of 1g) and stick movement/g (ditto mutatis mutandis) must increase (or at least not decrease) with an increase in AoA (thanks to Clive Leyman for this formulation). I understand that in flight test, in which “wind-up turns” were conducted (a turn with increasing angle of bank; an increasing angle of bank means ceteris paribus increasing AoA), this condition was not fulfilled. -- https://abnormaldistribution.org/index.php/2019/04/30/ieee-spectrum-on-possible-software-involvement-in-two-recent-airliner-crashes/ https://abnormaldistribution.org/index.php/2019/04/30/ieee-s...
    - Stierlitz 6y ago
salawat 6y ago
The issue isn't a really a physical one in principle here. It's an issue of corporate accountability. You had corners cut to deliver a product that ended up killing people. There is no real room for doubt in that just from the material we have available. So, what? What happens? What should happen? Everything go back to "normal"? Let the same people who ran things continue to profit off their wrongdoing? Accept that as long as you're one of only two rides in town that you have the security to deliver and recover from delivering a lethal product? That's the issue. That's the reality we're taking out of this. It isn't even self-regulating anymore. There is no bankruptcy, no hammer, no reallocation of assets to those that can wield them more responsibly, no reset. Just a token gesture. The same Goliath just shrugs and moves on. While I get that might be tenable or desirable to some, I'm not one of them. Realistic risk of falling flat on your face, being held to account, and not being able to just shrug it off and keep going keeps you honest. Once you lose that, "What's a life here and there? Doesn't bother me. Can't make an onelette without cracking a few eggs." The economy is not an omelette, and people are not eggs. Either we serve it, or it serves us. I know which side of that assertion I'm on.
- skybrian 6y ago
  The CEO resigned, so it's questionable whether there are the same people running things. How much other management changed?
  - windthrown 6y ago
    The replacement CEO was previously the chairman of the board. So while they did change personnel, I am skeptical about how different their actual management practices are.
- pdonis 6y ago
  What alternative would you propose? You can't just remove Boeing as a company: they have tens of thousands of existing aircraft in the field that need to be maintained, and a large number of people who were not at fault in all of this whose jobs would be eliminated. So how do you hold the proper people accountable without doing so much collateral damage that the cost of that outweighs the benefits? Also, responsibility doesn't just like with Boeing; the FAA certified the 737 MAX, and the rules that allowed that to happen were written by lawmakers and bureaucrats over a period of decades. How do you hold all of them accountable? Many, if not most, of those people aren't even actively working any more.

kayodelycaon 6y ago

Tail rudder problems is putting it mildly. There was malfunction with a valve that would cause the rudder to move in the opposite direction of the control inputs.

cdolan 6y ago
Correct. Flight 427 to Pittsburgh. My wife’s father was on the flight. The tail’s controls inverted in freezing temperatures.
- sillysaurusx 6y ago
  Wait, what? Anyone have any more info on this? It seems completely insane for flight control inputs to invert themselves, but only in certain temperatures. I'd love to see the incident report on that... EDIT: Ah: https://en.wikipedia.org/wiki/USAir_Flight_427 https://en.wikipedia.org/wiki/USAir_Flight_427 I'm so sorry that happened to your wife's father. The accident report is here: https://www.ntsb.gov/investigations/AccidentReports/Reports/AAR9901.pdf https://www.ntsb.gov/investigations/AccidentReports/Reports/... Section 2.7.2 is interesting: 2.7.2 Unusual Attitude Training for Boeing 737 Pilots At the time of the USAir flight 427 accident, no air carrier training programs were specifically aimed at training 737 pilots to recognize and address a rudder jam or reversal. The guidance available at that time from Boeing advised pilots, as a first consideration, to maintain or regain full control of the airplane. Specifically, the guidance advised pilots to counter unwanted roll tendencies from a malfunctioning rudder with the application of up to full aileron control inputs. However, the guidance did not advise pilots that, at some airspeeds, an uncommanded full rudder input could not be successfully opposed by full wheel (aileron and spoiler) inputs and that a reduction in the airplane’s angle-of-attack could improve the effectiveness of the roll controls relative to the effectiveness of the rudder. Boeing’s guidance for relieving a jammed rudder informed pilots only that they should use maximum force to overpower the jam and specifically warned pilots against turning off flight control switches “unless the faulty control was positively identified.” No additional guidance was provided about the effects of flight control switch selections on rudder jam conditions.
  - cdolan 6y ago
    If I start reading I go for hours haha. Am I correct that it inverted/reversed?
    - sillysaurusx 6y ago
      Yes, but I'm not sure why it inverted. If you open the accident report (https://www.ntsb.gov/investigations/AccidentReports/Reports/AAR9901.pdf https://www.ntsb.gov/investigations/AccidentReports/Reports/...) and ctrl-F "rudder", you get 2,112 matches. So "reading for hours" is a distinct possibility in this case... (Oh, by the way, I didn't mean to imply you were mistaken, or anything like that. I was just so shocked that a plane's controls could invert themselves in any conceivable circumstance. Currently digging through the accident report to try to figure out what happened.) "the probable cause of the USAir flight 427 accident was a loss of control of the airplane resulting from the movement of the rudder surface to its blowdown limit. The rudder surface most likely deflected in a direction opposite to that commanded by the pilots as a result of a jam of the main rudder power control unit servo valve secondary slide to the servo valve housing offset from its neutral position and overtravel of the primary slide" Unfortunately I don't know what most of these terms mean. It sounds like it might be saying "they moved the rudder to its limit, and then it jammed at the limit; so when they tried to command the rudder to go the other way, the rudder was pointed in the opposite direction of the control inputs." But I'm really not sure.
      - cdolan 6y ago
        No offense taken. I meant that if I start researching it again I’ll be up for 5 hours because of the personal ties to it. My recollection in researching this a decade ago was that the cold weather made the behavior of the rudder change (my term was invert, maybe that’s not accurate), and pilots were trying to pull up, but in fact putting the plane deeper into a nosedive. Some 25 seconds later they hit the ground at some 300-400 MPH and vaporized. The only way to have saved the plane would have been to dump the hydraulics and/or switch to a manual fly by wire mode, neither of which were a logici thing to do in the 15 seconds they had to save the flight. I’ve only flown for 20 hours in a Cessna so sorry if my terminology isn’t perfect!

bigbob2 6y ago

In that case maybe I'll give it 50 years to develop the same safety record.

Analemma_ 6y ago

The original 737 wasn't broken-by-design in the way the Max is. The Max _requires_ software kludges to paper over its deliberate mistakes; that's very different from just having a few bugs to work out in a fundamentally sound design.

HPsquared 6y ago
This is a bit of an urban myth that keeps flying around. The plane is perfectly stable without MCAS, but would have had different handling characteristics than the previous version. The purpose of MCAS was to modify the handling to match the previous plane, so pilots' type ratings would carry over with minimal retraining. At its heart, it was a (poorly implemented) kludge in an attempt to sidestep a lot of paperwork.
- throwaway201103 6y ago
  You're mostly right, but it wasn't just to make it handle like the previous versions, it was to satisfy FAA certification rules on how it handled.
  - cjbprime 6y ago
    This is my understanding too, though Boeing hasn't really come out and said it definitively. Specifically: > MCAS was devised to fulfill an airworthiness certification condition in 14 CFR 25.173 and 14 CFR 25.175. In high angle-of-attack (AoA) flight configuration, it is required that stick force/g (the stick force necessary to produce (hold) an incremental normal acceleration of 1g) and stick movement/g (ditto mutatis mutandis) must increase (or at least not decrease) with an increase in AoA (thanks to Clive Leyman for this formulation). I understand that in flight test, in which “wind-up turns” were conducted (a turn with increasing angle of bank; an increasing angle of bank means ceteris paribus increasing AoA), this condition was not fulfilled. -- https://abnormaldistribution.org/index.php/2019/04/30/ieee-spectrum-on-possible-software-involvement-in-two-recent-airliner-crashes/ https://abnormaldistribution.org/index.php/2019/04/30/ieee-s...
  - Stierlitz 6y ago

salawat 6y ago

The issue isn't a really a physical one in principle here. It's an issue of corporate accountability. You had corners cut to deliver a product that ended up killing people. There is no real room for doubt in that just from the material we have available. So, what? What happens? What should happen? Everything go back to "normal"? Let the same people who ran things continue to profit off their wrongdoing? Accept that as long as you're one of only two rides in town that you have the security to deliver and recover from delivering a lethal product? That's the issue. That's the reality we're taking out of this. It isn't even self-regulating anymore. There is no bankruptcy, no hammer, no reallocation of assets to those that can wield them more responsibly, no reset. Just a token gesture. The same Goliath just shrugs and moves on. While I get that might be tenable or desirable to some, I'm not one of them. Realistic risk of falling flat on your face, being held to account, and not being able to just shrug it off and keep going keeps you honest. Once you lose that, "What's a life here and there? Doesn't bother me. Can't make an onelette without cracking a few eggs." The economy is not an omelette, and people are not eggs. Either we serve it, or it serves us. I know which side of that assertion I'm on.

skybrian 6y ago
The CEO resigned, so it's questionable whether there are the same people running things. How much other management changed?
- windthrown 6y ago
  The replacement CEO was previously the chairman of the board. So while they did change personnel, I am skeptical about how different their actual management practices are.
pdonis 6y ago
What alternative would you propose? You can't just remove Boeing as a company: they have tens of thousands of existing aircraft in the field that need to be maintained, and a large number of people who were not at fault in all of this whose jobs would be eliminated. So how do you hold the proper people accountable without doing so much collateral damage that the cost of that outweighs the benefits? Also, responsibility doesn't just like with Boeing; the FAA certified the 737 MAX, and the rules that allowed that to happen were written by lawmakers and bureaucrats over a period of decades. How do you hold all of them accountable? Many, if not most, of those people aren't even actively working any more.