Three AOA sensors inputting to MCAS two of which must agree.
Limitation to the forward trim provided by MCAS?
They would do it for me. How difficult/expensive to fit/retrofit.
Prob just a software upgrade. FCC A & B should have a crosstalk bus between the 2. Boeing boffins are probably working on a solution now in order to ensure a single sensor failure does not impact safe aircraft operating envelopes. Both sensors will prob be voted/compared if they weren't previously, or the MCAS deactivated.
Single sensor inputs compared over crosstalk buses between aircraft system computers (redundancies) for the purpose of voting/comparison have often been used in the past. Not sure why single AOA inputs to the FCC were not voted in the first place (if this is the case).