5 ms·

Can anyone who is following this closely provide a good link to a summary of what has actually been fixed?

garmaine 6y ago
The manual.
dudus 6y ago
Read in passing that the system does not activate multiple times in sequence, and there's an extra sensor input for the pitch (previously it was a single one). Besides the manual being more explicit on the correct workaround. Don't have a source though.
kayfox 6y ago
The following: * Changes to the trim system electrical wiring to prevent possible shorts (none have been reported so far). * Changes to the flight laws in the computers to limit MCAS activation authority (how far it moves), limit activation to a single activation, require agreement between AoA sensors and other fixes. * Changes to the manual to outline MCAS system, interaction with other automatic trim systems, normal and non-normal (emergency) procedures. * Changes to baseline training to include more trim system troubleshooting, MCAS system theory and troubleshooting, AoA sensor indications, etc. * Changes in advanced training program recommendations for airlines. There's about 900 individual changes from this, a number of which don't have anything to do with MCAS but were recommended while examining literally every aspect of the aircraft. So the above list is quite incomplete. https://www.federalregister.gov/documents/2020/11/20/2020-25844/airworthiness-directives-the-boeing-company-airplanes https://www.federalregister.gov/documents/2020/11/20/2020-25...
- greesil 6y ago
  Thank you.
linuxftw 6y ago
Nothing was fixed. MCAS simply disables itself if it hits any number of problems. The FAA and the nor the NTSB released any data or appeared to inquire if operating the MAX without the MCAS enabled is safe. They made vague statements like "MCAS only operates in rare flight conditions" without any quantification of "rare." We don't know if a single plane has successfully taken off or landed with MCAS disabled. The real problem that was never addressed is the FAA's complete lack of competence when it comes to certifying the safeness of flight control systems. The same incompetent group of people that approved the planes in the first place are still in charge.
- tzs 6y ago
  > We don't know if a single plane has successfully taken off or landed with MCAS disabled. Almost all of them have. MCAS is only enabled when flaps are up.
- kayfox 6y ago
  Its not legal for the MAX to be flown without MCAS. It corrects a control force issue that must be corrected for it to obtain an airworthiness certificate. Cite: FARs §25.173, §25.175.
  - linuxftw 6y ago
    "Force control issue" is Boeing-speak for "anti-stall." If you're holding the stick back, increase thrust, backwards pressure on stick needed to lift nose reduces, you stall and die. What we don't know is how often MCAS actually operated on flights, so we don't know how necessary this component really is. All we know is that Boeing claims it's 'rare' and the FAA did not challenge them on this statement. Unless you have the data, you're repeating their talking points.
    - kayfox 6y ago
      Engine thrust related nose up forces would be less on the MAX as the engines are closer to the CG and CL. What is being compensated for is the change of the center of lift as the AoA changes because of where the engine nacelle is and how big it is. Also, the data that you are expecting the FAA to report on was not being collected by the FAA. You will also note the FAA did not provide any data on how frequently the TOGO switch is used in the Atlas Air investigation, because just like MCAS it is a system that may be activated on normal flights.

The manual.

Read in passing that the system does not activate multiple times in sequence, and there's an extra sensor input for the pitch (previously it was a single one). Besides the manual being more explicit on the correct workaround. Don't have a source though.

kayfox 6y ago

The following: * Changes to the trim system electrical wiring to prevent possible shorts (none have been reported so far). * Changes to the flight laws in the computers to limit MCAS activation authority (how far it moves), limit activation to a single activation, require agreement between AoA sensors and other fixes. * Changes to the manual to outline MCAS system, interaction with other automatic trim systems, normal and non-normal (emergency) procedures. * Changes to baseline training to include more trim system troubleshooting, MCAS system theory and troubleshooting, AoA sensor indications, etc. * Changes in advanced training program recommendations for airlines. There's about 900 individual changes from this, a number of which don't have anything to do with MCAS but were recommended while examining literally every aspect of the aircraft. So the above list is quite incomplete. https://www.federalregister.gov/documents/2020/11/20/2020-25844/airworthiness-directives-the-boeing-company-airplanes https://www.federalregister.gov/documents/2020/11/20/2020-25...

greesil 6y ago
Thank you.

linuxftw 6y ago

Nothing was fixed. MCAS simply disables itself if it hits any number of problems. The FAA and the nor the NTSB released any data or appeared to inquire if operating the MAX without the MCAS enabled is safe. They made vague statements like "MCAS only operates in rare flight conditions" without any quantification of "rare." We don't know if a single plane has successfully taken off or landed with MCAS disabled. The real problem that was never addressed is the FAA's complete lack of competence when it comes to certifying the safeness of flight control systems. The same incompetent group of people that approved the planes in the first place are still in charge.

tzs 6y ago
> We don't know if a single plane has successfully taken off or landed with MCAS disabled. Almost all of them have. MCAS is only enabled when flaps are up.
kayfox 6y ago
Its not legal for the MAX to be flown without MCAS. It corrects a control force issue that must be corrected for it to obtain an airworthiness certificate. Cite: FARs §25.173, §25.175.
- linuxftw 6y ago
  "Force control issue" is Boeing-speak for "anti-stall." If you're holding the stick back, increase thrust, backwards pressure on stick needed to lift nose reduces, you stall and die. What we don't know is how often MCAS actually operated on flights, so we don't know how necessary this component really is. All we know is that Boeing claims it's 'rare' and the FAA did not challenge them on this statement. Unless you have the data, you're repeating their talking points.
  - kayfox 6y ago
    Engine thrust related nose up forces would be less on the MAX as the engines are closer to the CG and CL. What is being compensated for is the change of the center of lift as the AoA changes because of where the engine nacelle is and how big it is. Also, the data that you are expecting the FAA to report on was not being collected by the FAA. You will also note the FAA did not provide any data on how frequently the TOGO switch is used in the Atlas Air investigation, because just like MCAS it is a system that may be activated on normal flights.