Boeing 737 Max: Automated Crashes [video]
As I see it there are several critical flaws in the MAX.<p>First, the engine placement means it has a non-linear control force curve, so it needs some system to compensate for that. Hence MCAS. This is because the landing gear can&#x27;t be lengthened without expanding the gear bays, which would void the type certificate AFAICT.<p>Second, the larger size of the plane means that a single pilot cannot be guaranteed to be able to use the manual trim wheels in all flight modes. The force required is extreme, weaker pilots may not be capable of trimming the aircraft. This can&#x27;t be fixed without changing the trim wheel size (which requires a new cockpit layout) and&#x2F;or the horizontal stabilizer, both of which would void the type certificate.<p>Third, critical flight control systems need to be triple-redundant, and there are only two AOA sensors. Since the plane cannot be certified without MCAS (point 1) and MCAS can command a catastrophic failure (see two craters) it should be a triple-redundant system. A new AOA sensor would void the type certificate.<p>Canada stated that they would certify the MAX without MCAS and with required pilot training, if its performance characteristics were acceptable. Boeing has made no attempt (AFAICT) to try this, which raises suspicion that MCAS is in fact required for certification, which would make it a Fly-By-Wire system (and subject to appropriate regulations, requiring hardware changes) and not just a stability augmentation system. Essentially Canada called Boeing&#x27;s bluff.<p>It&#x27;s not the software that&#x27;s the (only) issue. If it were, the plane would be flying by now.