Originally Posted by
DaveReidUK
Yes, the L and R AoA sensors on the 737 are interchangeable, so for a given AoA they will generate rotational signals in the opposite sense to each other. At the very least, the ADIRUs will have to resolve that.
In which case the software in the ADRIUs *has* to be different, one side has to add the correction, the other has to subtract it. I can well believe from bitter experience that the software team did not know enough about the hardware subtlety to appreciate that the ADIRU software has to have a L and a R version. This would explain why testing and peer reviewing did not spot anything wrong, the software met its spec!
A correction table would also explain the different offsets. I would expect the table to be a 'look-up' table using air speed as the selector. As the airspeed went up it would reach a point where the next value in the table has to be used, so there would be a step change in the correction. So, I would expect the first value in the correction table to be about 6 deg (to give a 12 deg offset), the next value to be about 8 deg and the final value to be about 11 deg.