Boeing 737 Max Crashes: Sensors Vulnerable to Failure

Re:Boeing 737 Max Crashes: Sensors Vulnerable to Failure by cmurf on Thursday April 11, 2019 @02:45PM (#19637851)

I don't think that's accurate or consistent enough to meet the requirements of FAR 25.207. Load factor is constantly changing in flight. You only have a constant load factor with zero turbulence and ~~straight and level flight~~ unaccelerated flight. edited Obviously I can climb at 500fpm at 1.0g, but if the rate itself is changing I'm at something other than 1.0g.

It also can't withstand failure of the selected pitot-static system, because it depends directly on it. So now you need a mechanism to detect such failures, and use a different pitot-static system, and do all of that switching while maintaining the requirements in FAR 25.207. I'm unconvinced that's feasible.

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Re:Boeing 737 Max Crashes: Sensors Vulnerable to Failure by lutorm on Thursday April 11, 2019 @03:33PM (#19638294)

Pitot-static failure is already a big deal for much more immediate reasons than an AoA estimate. And I'm puzzled why load factor changing would be a problem? The air data computer knows what the load factor is at any given time.

To be clear: I didn't imply that you'd want to use this as the single source of AoA, only that you can use this in concert with the physical sensors to determine if the sensors are producing a valid value. You need 3 sources to be able to throw out a bad measurement, 2 AoA sensors and an airspeed-based measurement should be a perfectly valid, single-fault-tolerant, way to outvote a bad sensor.

Remember that these accidents happened at high airspeed. You'd rip the wings off the airplane before you'd stall it at those speeds. It's not a subtle failure.

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