7 ms·

Boeing 737 Max production hit by a new defect

31 points by throw7 3y ago

dtagames 3y ago
The TL;DR: The tail of 737 MAXs going up to 4 years back is not attached correctly. What could go wrong?
- pie420 3y ago
  This is exactly what happens when you replace engineers with bean counters.
  - ElfinTrousers 3y ago
    Same thing with rail, that's why American freight trains seem to want to go anywhere except along the rails lately.
- singleshot_ 3y ago
  Well the good news is, although they call it the vertical tail in the article, it’s not the whole tail that will fall off, just the vertical stabilizer.
  - Tsiklon 3y ago
    Is that the component of the aircraft that allows it to yaw? If so, I imagine it’s less than ideal for this to fall off at speed.
    - singleshot_ 3y ago
      Let’s say that it would severely complicate the remainder of the flight which would not be likely to last very long. This tragically happened to an airbus flown as American 587 shortly after 9/11. It crashed into a neighborhood in New York City after it encountered wake turbulence from another jet and one of the pilots responded too aggressively with the rudder. Truly a horrifying incident. Parenthetically I don’t recall whether this was a training issue, a software issue, or a pilot error. Accordingly, I don’t want to sound like I’m slamming the pilot. On the other hand I’ve seen a B-52 lose just about the entirety of its vertical stabilizer and it didn’t seem to care at all; landed safely.
      - labcomputer 3y ago
        > Parenthetically I don’t recall whether this was a training issue, a software issue, or a pilot error. Accordingly, I don’t want to sound like I’m slamming the pilot. It was a design issue, which many people like to blame on the pilot because they don't know any better. The problem was that the rate-of-change of control-force per rudder angle is/was negative for that particular Airbus model... which is generally known to lead to PIO (pilot induced oscillations). When I say generally known, I mean it has been documented since at least as early as pre-WWII NACA (the precursor to NASA) studies. In fact, that's what led to the installation of MCAS on 737 Max's: The FAA requires that, for the elevator (but not rudder), the control force should increase as deflection increases. So Boeing tried to simulate that behavior with elevator trim + software. In other words, MCAS was a bad, hacky "solution" to a problem very similar to what happened on AA587 (but for pitch instead of yaw). > On the other hand I’ve seen a B-52 lose just about the entirety of its vertical stabilizer and it didn’t seem to care at all; landed safely. Yea, but a B-52 probably has more elevator authority than most commercial airliners (both because it is meant to go supersonic and need to deal with Mach tuck and because B-52 is expected to shed some "payload" while airborne). The problem is that the vertical stabilizer weighs a ton and is waaaay out at the end of the fuselage, so it really throws off your weight and balance if it falls off.
        singleshot_ 3y ago
        This sounded a little sus so I read the NTSB report which did not point the finger the way you said. My limited knowledge about the BUFF is that if you achieve supersonic flight in one, you are _definitely_ doing it wrong. My impression of what the purpose of MCAS is for has, accordingly, not been influenced much by your comment.
    - singleshot_ 3y ago
      (Yes, it controls yaw, but in some sense every vertical surface on a plane including the sides of the fuselage also contribute some yaw stability).
- shrike 3y ago
  While that may be true, it's not what Spirit has said. They have reported that "...a non-standard manufacturing process..." was used to assemble "two of eight points where the vertical fin is attached to the fuselage.". As an example; this could be as minor as using a riveting tool that hadn't been inspected on the correct schedule but was still operating as expected. It could be far more serious; perhaps that riveting tool was operating at a dangerously low pressure resulting in a poorly attached vertical fin. We don't know yet. If this had happened before the 737 Max debacle I would have complete trust in Boeing's and the FAA's assessment that "...that there is no immediate safety issue.”. As it is I can't help being a little skeptical, that loss of trust is a real shame.
  - inferiorhuman 3y ago
    As an example; this could be as minor as using a riveting tool that hadn't been inspected on the correct schedule but was still operating as expected. It could be far more serious; perhaps that riveting tool was operating at a dangerously low pressure resulting in a poorly attached vertical fin. Based on past performance I think it's safe to say it's not a "tool wasn't calibrated" issue by any stretch. While the 787 that was assembled with Home Depot fasteners was junked, Boeing did sell plenty of 737 NGs with handmade structural components where CNC'd ones were specified. Al Jazeera has a good documentary on this. The MAX got slat tracks that weren't up to spec. No immediate safety issue pretty much means what it says. Planes aren't likely to be falling out of the sky today, but given enough time things will likely fail.
- yunohn 3y ago
  Comically relevant: Clark & Dave - The Front Fell Off https://youtu.be/3m5qxZm_JqM https://youtu.be/3m5qxZm_JqM
exabrial 3y ago
Flown on a 737 Max many times and honestly never thought about it twice since it was re-instated. All airplanes should undergo the level of scrutiny this one does. It's probably a form survivor bias: https://www.scribbr.com/research-bias/survivorship-bias https://www.scribbr.com/research-bias/survivorship-bias especially when news media is involved since they amplify sensationalism in hopes to generate ad revenue. Glad to see it's under intense scrutiny and problems are being identified, addressed, and fixed, just sad not all planes get this much attention. It's not like every other manufacturer is perfect and nails it every time with riveting success.
- dtagames 3y ago
  You might want to investigate the book Flying Blind[0]. It's the true story of how the 737 MAX was cursed from the beginning and is a byproduct of Boeing's haven given up on its engineering culture since the McDonnel Douglas merger. It's not a safe plane. It's a set of bad compromises which has cost the company more than designing a safe plane from the start. [0] https://www.penguinrandomhouse.com/books/646497/flying-blind-by-peter-robison/ https://www.penguinrandomhouse.com/books/646497/flying-blind...
- greatgib 3y ago
  You will say that until the day you will die in a crash. This is not an issue with media, but the thing that this plane was designed using shortcuts, cost cutting mind and with as little oversight as possible. Si it is logic for so many defects to show up . Remember that the persons that were giving the certification to Boeing were it's own employees... Just now imagine that they had to rush to find acceptable hacks to be able to have their plane back in service. The fastest possible.
  - stouset 3y ago
    > You will say that until the day you will die in a crash. For christ’s sake, this level of hyperbole is completely unjustified. A supplier found a non-safety-critical flaw in a component they were manufacturing. It’s being fixed for new planes, and a plan is being devised to retrofit a fix on existing fleets. What more do you want? Yes, the earlier issues with the MCAS and single AOA sensor were tragic and highlighted serious and inexcusable deficiencies within both Boeing and the FAA. And yet, since resolving this issue, the 737 MAX has returned to service with an exemplary safety record. Flying on a 737 MAX—even including the fatal crashes due to MCAS—remains quite literally the safest way to travel by both time and distance. Chill.
Havoc 3y ago
It’s clearly cursed. Just convert to cargo and call it a day.
- jeffrallen 3y ago
  I don't think the cargo pilots' union would agree with that plan...
  - Havoc 3y ago
    Well I guess they can write a complaint to Boeing. And maybe the FAA too over overseeing this self certify circus

31 points by throw7 3y ago

dtagames 3y ago

The TL;DR: The tail of 737 MAXs going up to 4 years back is not attached correctly. What could go wrong?

pie420 3y ago
This is exactly what happens when you replace engineers with bean counters.
- ElfinTrousers 3y ago
  Same thing with rail, that's why American freight trains seem to want to go anywhere except along the rails lately.
singleshot_ 3y ago
Well the good news is, although they call it the vertical tail in the article, it’s not the whole tail that will fall off, just the vertical stabilizer.
- Tsiklon 3y ago
  Is that the component of the aircraft that allows it to yaw? If so, I imagine it’s less than ideal for this to fall off at speed.
  - singleshot_ 3y ago
    Let’s say that it would severely complicate the remainder of the flight which would not be likely to last very long. This tragically happened to an airbus flown as American 587 shortly after 9/11. It crashed into a neighborhood in New York City after it encountered wake turbulence from another jet and one of the pilots responded too aggressively with the rudder. Truly a horrifying incident. Parenthetically I don’t recall whether this was a training issue, a software issue, or a pilot error. Accordingly, I don’t want to sound like I’m slamming the pilot. On the other hand I’ve seen a B-52 lose just about the entirety of its vertical stabilizer and it didn’t seem to care at all; landed safely.
    - labcomputer 3y ago
      > Parenthetically I don’t recall whether this was a training issue, a software issue, or a pilot error. Accordingly, I don’t want to sound like I’m slamming the pilot. It was a design issue, which many people like to blame on the pilot because they don't know any better. The problem was that the rate-of-change of control-force per rudder angle is/was negative for that particular Airbus model... which is generally known to lead to PIO (pilot induced oscillations). When I say generally known, I mean it has been documented since at least as early as pre-WWII NACA (the precursor to NASA) studies. In fact, that's what led to the installation of MCAS on 737 Max's: The FAA requires that, for the elevator (but not rudder), the control force should increase as deflection increases. So Boeing tried to simulate that behavior with elevator trim + software. In other words, MCAS was a bad, hacky "solution" to a problem very similar to what happened on AA587 (but for pitch instead of yaw). > On the other hand I’ve seen a B-52 lose just about the entirety of its vertical stabilizer and it didn’t seem to care at all; landed safely. Yea, but a B-52 probably has more elevator authority than most commercial airliners (both because it is meant to go supersonic and need to deal with Mach tuck and because B-52 is expected to shed some "payload" while airborne). The problem is that the vertical stabilizer weighs a ton and is waaaay out at the end of the fuselage, so it really throws off your weight and balance if it falls off.
      - singleshot_ 3y ago
        This sounded a little sus so I read the NTSB report which did not point the finger the way you said. My limited knowledge about the BUFF is that if you achieve supersonic flight in one, you are _definitely_ doing it wrong. My impression of what the purpose of MCAS is for has, accordingly, not been influenced much by your comment.
  - singleshot_ 3y ago
    (Yes, it controls yaw, but in some sense every vertical surface on a plane including the sides of the fuselage also contribute some yaw stability).
shrike 3y ago
While that may be true, it's not what Spirit has said. They have reported that "...a non-standard manufacturing process..." was used to assemble "two of eight points where the vertical fin is attached to the fuselage.". As an example; this could be as minor as using a riveting tool that hadn't been inspected on the correct schedule but was still operating as expected. It could be far more serious; perhaps that riveting tool was operating at a dangerously low pressure resulting in a poorly attached vertical fin. We don't know yet. If this had happened before the 737 Max debacle I would have complete trust in Boeing's and the FAA's assessment that "...that there is no immediate safety issue.”. As it is I can't help being a little skeptical, that loss of trust is a real shame.
- inferiorhuman 3y ago
  As an example; this could be as minor as using a riveting tool that hadn't been inspected on the correct schedule but was still operating as expected. It could be far more serious; perhaps that riveting tool was operating at a dangerously low pressure resulting in a poorly attached vertical fin. Based on past performance I think it's safe to say it's not a "tool wasn't calibrated" issue by any stretch. While the 787 that was assembled with Home Depot fasteners was junked, Boeing did sell plenty of 737 NGs with handmade structural components where CNC'd ones were specified. Al Jazeera has a good documentary on this. The MAX got slat tracks that weren't up to spec. No immediate safety issue pretty much means what it says. Planes aren't likely to be falling out of the sky today, but given enough time things will likely fail.
yunohn 3y ago
Comically relevant: Clark & Dave - The Front Fell Off https://youtu.be/3m5qxZm_JqM https://youtu.be/3m5qxZm_JqM

exabrial 3y ago

Flown on a 737 Max many times and honestly never thought about it twice since it was re-instated. All airplanes should undergo the level of scrutiny this one does. It's probably a form survivor bias: https://www.scribbr.com/research-bias/survivorship-bias https://www.scribbr.com/research-bias/survivorship-bias especially when news media is involved since they amplify sensationalism in hopes to generate ad revenue. Glad to see it's under intense scrutiny and problems are being identified, addressed, and fixed, just sad not all planes get this much attention. It's not like every other manufacturer is perfect and nails it every time with riveting success.

dtagames 3y ago
You might want to investigate the book Flying Blind[0]. It's the true story of how the 737 MAX was cursed from the beginning and is a byproduct of Boeing's haven given up on its engineering culture since the McDonnel Douglas merger. It's not a safe plane. It's a set of bad compromises which has cost the company more than designing a safe plane from the start. [0] https://www.penguinrandomhouse.com/books/646497/flying-blind-by-peter-robison/ https://www.penguinrandomhouse.com/books/646497/flying-blind...
greatgib 3y ago
You will say that until the day you will die in a crash. This is not an issue with media, but the thing that this plane was designed using shortcuts, cost cutting mind and with as little oversight as possible. Si it is logic for so many defects to show up . Remember that the persons that were giving the certification to Boeing were it's own employees... Just now imagine that they had to rush to find acceptable hacks to be able to have their plane back in service. The fastest possible.
- stouset 3y ago
  > You will say that until the day you will die in a crash. For christ’s sake, this level of hyperbole is completely unjustified. A supplier found a non-safety-critical flaw in a component they were manufacturing. It’s being fixed for new planes, and a plan is being devised to retrofit a fix on existing fleets. What more do you want? Yes, the earlier issues with the MCAS and single AOA sensor were tragic and highlighted serious and inexcusable deficiencies within both Boeing and the FAA. And yet, since resolving this issue, the 737 MAX has returned to service with an exemplary safety record. Flying on a 737 MAX—even including the fatal crashes due to MCAS—remains quite literally the safest way to travel by both time and distance. Chill.

Havoc 3y ago

It’s clearly cursed. Just convert to cargo and call it a day.

jeffrallen 3y ago
I don't think the cargo pilots' union would agree with that plan...
- Havoc 3y ago
  Well I guess they can write a complaint to Boeing. And maybe the FAA too over overseeing this self certify circus