4 ms·

And yet only the 737 Max needed a software fix

by petilon 7y ago

na85 7y ago
That's because the pitch-up behavior isn't actually the problem.
- petilon 7y ago
  [Boeing] engineers observed a tendency for the plane’s nose to pitch upward during a specific extreme maneuver. After other efforts to fix the problem failed, the solution they arrived at was a piece of software — the Maneuvering Characteristics Augmentation System (MCAS) — that would move a powerful control surface at the tail to push the airplane’s nose down. Source: https://www.seattletimes.com/seattle-news/times-watchdog/the-inside-story-of-mcas-how-boeings-737-max-system-gained-power-and-lost-safeguards/ https://www.seattletimes.com/seattle-news/times-watchdog/the...
  - na85 7y ago
    Sorry, but the Seattle Times is not a competent source when it comes to reporting aerodynamics. Any standard-configuration airliner will pitch up when you throttle up at low speed.
- inferiorhuman 7y ago
  That's because the pitch-up behavior isn't actually the problem. The pitch-power coupling has been problematic on the 737 since Boeing went with GE engines. Thomsonfly almost got a classic to stall in Bournemouth ages ago and flyDubai managed to wreck an NG in Russia a couple years ago. It's possible, but unlikely, the 737 MAX is better behaved in this regard. If there weren't significant aerodynamic problems with the 737 MAX it would be flying by now. This whole type cert / training thing is a red herring. The cost of slow and shuttering production both in financial and diplomatic terms far outstrips the cost of a separate type. Beyond that Boeing has a captive market. The only 737 MAX alternatives out there are made by Airbus, and Airbus has a healthy backlog for both the A220 and A320. While some airlines may be able to take the range / consumption hit with an NG other airlines, like Norwegian, were counting on the increased range of the MAX for certain routes.
  - na85 7y ago
    Are you suggesting that a 320 won't pitch up if you firewall the throttle at low indicated? You have two massive sources of thrust below the centre of gravity. If you advance the throttle it will create a nose-up pitching moment.
    - inferiorhuman 7y ago
      Are you suggesting that a 320 won't pitch up if you firewall the throttle at low indicated? Correct. An A320 won't pitch up as dramatically as a 737, mostly due to FBW magic.
      - na85 7y ago
        >An A320 won't pitch up as dramatically as a 737 Ok, glad we agree it'll still pitch up.
        inferiorhuman 7y ago
        Ok, glad we agree it'll still pitch up. Sure, the difference is that a 737 Classic, NG, or MAX with all of the nannies working can be flown into a stall with lots of throttle at low speed whereas the Airbus cannot. The pitch-power coupling on a 737 is far more problematic than on its competitors.

And yet only the 737 Max needed a software fix

na85 7y ago

That's because the pitch-up behavior isn't actually the problem.

petilon 7y ago
[Boeing] engineers observed a tendency for the plane’s nose to pitch upward during a specific extreme maneuver. After other efforts to fix the problem failed, the solution they arrived at was a piece of software — the Maneuvering Characteristics Augmentation System (MCAS) — that would move a powerful control surface at the tail to push the airplane’s nose down. Source: https://www.seattletimes.com/seattle-news/times-watchdog/the-inside-story-of-mcas-how-boeings-737-max-system-gained-power-and-lost-safeguards/ https://www.seattletimes.com/seattle-news/times-watchdog/the...
- na85 7y ago
  Sorry, but the Seattle Times is not a competent source when it comes to reporting aerodynamics. Any standard-configuration airliner will pitch up when you throttle up at low speed.
inferiorhuman 7y ago
That's because the pitch-up behavior isn't actually the problem. The pitch-power coupling has been problematic on the 737 since Boeing went with GE engines. Thomsonfly almost got a classic to stall in Bournemouth ages ago and flyDubai managed to wreck an NG in Russia a couple years ago. It's possible, but unlikely, the 737 MAX is better behaved in this regard. If there weren't significant aerodynamic problems with the 737 MAX it would be flying by now. This whole type cert / training thing is a red herring. The cost of slow and shuttering production both in financial and diplomatic terms far outstrips the cost of a separate type. Beyond that Boeing has a captive market. The only 737 MAX alternatives out there are made by Airbus, and Airbus has a healthy backlog for both the A220 and A320. While some airlines may be able to take the range / consumption hit with an NG other airlines, like Norwegian, were counting on the increased range of the MAX for certain routes.
- na85 7y ago
  Are you suggesting that a 320 won't pitch up if you firewall the throttle at low indicated? You have two massive sources of thrust below the centre of gravity. If you advance the throttle it will create a nose-up pitching moment.
  - inferiorhuman 7y ago
    Are you suggesting that a 320 won't pitch up if you firewall the throttle at low indicated? Correct. An A320 won't pitch up as dramatically as a 737, mostly due to FBW magic.
    - na85 7y ago
      >An A320 won't pitch up as dramatically as a 737 Ok, glad we agree it'll still pitch up.
      - inferiorhuman 7y ago
        Ok, glad we agree it'll still pitch up. Sure, the difference is that a 737 Classic, NG, or MAX with all of the nannies working can be flown into a stall with lots of throttle at low speed whereas the Airbus cannot. The pitch-power coupling on a 737 is far more problematic than on its competitors.