B777 ADIRUs
The B777's ADIRU has 6 accelerometers with superior skewed axis combinations and redundancy.
When Pitots fail, any set of 3 sensors will define a solution vector in 3-space.
It follows that 6 non-parallel sensors result in 20-solution vectors.
If there are no errors, the solutions will all be the same within accuracy limits of the system.
If there is 1 faulty sensor,10 of the solution vectors become "wrong".
If a 2nd sensor fails, it also affects ten vectors but 4 are included in the first 10.
That means 2 failures results in 16 "wrong" out of twenty solutions.
The task of identifying the 4 "right" is done!
Last edited by Kimon; 1st January 2013 at 09:53.