Hi all,
Consider a B737 classic or NG, equipped with two IRS systems and two FCC's. Why is it that the pitch and roll signals from the IRS's to the FCC's are cross-coupled (i.e. IRS L feeds the pitch channel of FCC A and the roll channel of FCC B, while IRS R feeds the roll channel of FCC A and the pitch channel of FCC B)?
I think I'm probably missing something obvious here, but I really can't think of a good reason for the design to be like this. Isn't it true that this cross-coupling effectively negates the advantages of IRS redundancy, as a single failed IRS will now affect both autopilot/flight director systems, instead of only one?
Thanks!
