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The situation is pretty clear. They need to fix the wiring issue. Stick to the regulation or don't regulate... It's also shocking to me that the MAX may be rec

by ricw 7y ago

The situation is pretty clear. They need to fix the wiring issue. Stick to the regulation or don't regulate... It's also shocking to me that the MAX may be rectified when depending only on one angle-of-attack sensor (the one that caused the two prior crashes). They should mandate that at minimum 2 redundant sensor must exist, at minimum. Really it should be 3 sensors for flight critical input, as has been the case for all modern airplanes.

tyingq 7y ago
"It's also shocking to me that the MAX may be rectified when depending only on one angle-of-attack sensor" Do you have a source for this? Last I read, there were 3 main categories of fixes, the first being to read both sensors.[1] [1] https://www.businessinsider.com/boeing-737-max-mcas-fixes-2019-12 https://www.businessinsider.com/boeing-737-max-mcas-fixes-20...
pdonis 7y ago
> They need to fix the wiring issue. Stick to the regulation or don't regulate... Fixing the wiring issue would mean fixing it on every single 737 in service, not just the 737 MAX. Many of those airplanes have been flying for decades with no incidents. Tearing them apart to rewire them might make things worse overall, not better, since any repair always has the risk of introducing some other problem.
- WWLink 7y ago
  Or they could straight up say "no, we're calling this a brand new plane now and it has to meet modern certifications instead of being granted grandfathered status on things"
  - pdonis 7y ago
    Which would completely ignore the fact that non-MAX 737s have the same wiring issue. Remember, we're talking about the wiring issue now, not MCAS.
- Iwan-Zotow 7y ago
  > Fixing the wiring issue would mean fixing it on every single 737 in service, not just the 737 MAX. And? F.e., NHTSA has called the ongoing recall of airbags made by the major automotive parts supplier Takata "the largest and most complex safety recall in U.S. history.” Over 41.6 million vehicles have been recalled due to the faulty airbags. Different makes, models, years - but faulty part is faulty part and millions of cars were recalled and fixed.
  - pdonis 7y ago
    > millions of cars were recalled and fixed Replacing a faulty airbag on a car is a lot less complicated and risky than replacing many feet of wiring on an airplane.
    - chopin 7y ago
      Maybe, but there are fewer planes...
      - pdonis 7y ago
        It's not a matter of the number of planes, it's a matter of not wanting to create more problems than you solve. The risk of that is much higher when trying to rewire a plane than when replacing an airbag in a car.
- ohmaigad 7y ago
  > Fixing the wiring issue would mean fixing it on every single 737 in service, not just the 737 MAX. No it wouldn't as 737 was certified before the new regulation. It is in the article: > That earlier 737 NG model didn’t have to meet the current wiring-separation standards because they came into force long after that jet was certified. Just like with cars - you can drive a car from 70ties without airbags or crumple zones but you cannot buy a new car without airbags as it won't be able to pass the latest regulations. Imo in this case the main issue is not the safety (seeing how the older planes aren't falling out of the sky) but setting a precedent where the certification authority has missed an issue which is not according to regulation - do the manufacturer gets a free pass or it is their responsibility to make the item according to regulation in the first place and it doesn't matter if it was missed during the certification process.
  - pdonis 7y ago
    > No it wouldn't I know the previous 737 models were grandfathered. What I am questioning is the argument that, even though we accept this wiring flaw on all grandfathered 737s, it must be fixed on the 737 MAX just because Boeing made a different mistake (MCAS) on the 737 MAX. (If they hadn't made the MCAS mistake, the FAA wouldn't be reviewing the certification of the MAX and wouldn't have found the wiring issue.) > setting a precedent where the certification authority has missed an issue which is not according to regulation Is this the first time the FAA has missed a certification issue? I don't know, but I doubt it. If the FAA has missed certification issues before, has the manufacturer always been forced to rework all affected aircraft when the missed issue is discovered? Again, I don't know, but I doubt it. In any case, these certainly seem like relevant questions to ask before coming to a conclusion.
FriendlyNormie 7y ago
These sensors cannot possibly be expensive to build. Why aren’t there one hundred sensors on each plane? Trust whatever the majority of sensors report, notify that outliers need to be serviced.
- tyingq 7y ago
  I get your point, but they are largish mechanical sensors that require a hole in the hull. Here's an AoA sensor: https://i.stack.imgur.com/k0NTBm.jpg https://i.stack.imgur.com/k0NTBm.jpg They also require a computer that has the inputs for it. Why they didn't go with three is probably a good question. Airbus did.

by ricw 7y ago

tyingq 7y ago

"It's also shocking to me that the MAX may be rectified when depending only on one angle-of-attack sensor" Do you have a source for this? Last I read, there were 3 main categories of fixes, the first being to read both sensors.[1] [1] https://www.businessinsider.com/boeing-737-max-mcas-fixes-2019-12 https://www.businessinsider.com/boeing-737-max-mcas-fixes-20...

pdonis 7y ago

> They need to fix the wiring issue. Stick to the regulation or don't regulate... Fixing the wiring issue would mean fixing it on every single 737 in service, not just the 737 MAX. Many of those airplanes have been flying for decades with no incidents. Tearing them apart to rewire them might make things worse overall, not better, since any repair always has the risk of introducing some other problem.

WWLink 7y ago
Or they could straight up say "no, we're calling this a brand new plane now and it has to meet modern certifications instead of being granted grandfathered status on things"
- pdonis 7y ago
  Which would completely ignore the fact that non-MAX 737s have the same wiring issue. Remember, we're talking about the wiring issue now, not MCAS.
Iwan-Zotow 7y ago
> Fixing the wiring issue would mean fixing it on every single 737 in service, not just the 737 MAX. And? F.e., NHTSA has called the ongoing recall of airbags made by the major automotive parts supplier Takata "the largest and most complex safety recall in U.S. history.” Over 41.6 million vehicles have been recalled due to the faulty airbags. Different makes, models, years - but faulty part is faulty part and millions of cars were recalled and fixed.
- pdonis 7y ago
  > millions of cars were recalled and fixed Replacing a faulty airbag on a car is a lot less complicated and risky than replacing many feet of wiring on an airplane.
  - chopin 7y ago
    Maybe, but there are fewer planes...
    - pdonis 7y ago
      It's not a matter of the number of planes, it's a matter of not wanting to create more problems than you solve. The risk of that is much higher when trying to rewire a plane than when replacing an airbag in a car.
ohmaigad 7y ago
> Fixing the wiring issue would mean fixing it on every single 737 in service, not just the 737 MAX. No it wouldn't as 737 was certified before the new regulation. It is in the article: > That earlier 737 NG model didn’t have to meet the current wiring-separation standards because they came into force long after that jet was certified. Just like with cars - you can drive a car from 70ties without airbags or crumple zones but you cannot buy a new car without airbags as it won't be able to pass the latest regulations. Imo in this case the main issue is not the safety (seeing how the older planes aren't falling out of the sky) but setting a precedent where the certification authority has missed an issue which is not according to regulation - do the manufacturer gets a free pass or it is their responsibility to make the item according to regulation in the first place and it doesn't matter if it was missed during the certification process.
- pdonis 7y ago
  > No it wouldn't I know the previous 737 models were grandfathered. What I am questioning is the argument that, even though we accept this wiring flaw on all grandfathered 737s, it must be fixed on the 737 MAX just because Boeing made a different mistake (MCAS) on the 737 MAX. (If they hadn't made the MCAS mistake, the FAA wouldn't be reviewing the certification of the MAX and wouldn't have found the wiring issue.) > setting a precedent where the certification authority has missed an issue which is not according to regulation Is this the first time the FAA has missed a certification issue? I don't know, but I doubt it. If the FAA has missed certification issues before, has the manufacturer always been forced to rework all affected aircraft when the missed issue is discovered? Again, I don't know, but I doubt it. In any case, these certainly seem like relevant questions to ask before coming to a conclusion.

FriendlyNormie 7y ago

These sensors cannot possibly be expensive to build. Why aren’t there one hundred sensors on each plane? Trust whatever the majority of sensors report, notify that outliers need to be serviced.

tyingq 7y ago
I get your point, but they are largish mechanical sensors that require a hole in the hull. Here's an AoA sensor: https://i.stack.imgur.com/k0NTBm.jpg https://i.stack.imgur.com/k0NTBm.jpg They also require a computer that has the inputs for it. Why they didn't go with three is probably a good question. Airbus did.