Can you please explain the architecture. There are 3 FCPC (primary) and 2 FCSC (secondary) with FCPC#1 as the "master'. (A330)
My understanding is that all 4 FC + Master FC whether primary or secondary operate concurrently in all circumstances. In other words, they are not necessarily redundant and used only in a failure?
I did once know this off the top of my head, but now my brain hurts just thinking about it.
From the 380 flight manual. The 380 is a lot more capable than the 320/330, but the ideas are the same. In the 380, the SECs are identical computers to the PRIMs, though their functions are somewhat restricted. Engineering can interchange them though.
There are three PRIMs. Each PRIM can operate one or both APs, and/or FDs, and/or A/THR. Due to the fact that each PRIM can operate the A/THR, there are three A/THR channels.
To determine which PRIM will operate the engaged AP(s), FDs, and A/THR, each PRIM computes its operational capability, taking into account:
- Manual flight control law capability
- FE, AP, and approach capability
- A/THR capability.
The Master PRIM is the PRIM that has the best operational capability. The Slave 1 PRIM has the second best operational capability, and the Slave 2 PRIM has the third best.
When all the PRIMs have the same capability:- PRIM1 is the Master PRIM
- PRIM2 is the Slave 1 PRIM
- PRIM3 is the Slave 2 PRIM.
The Master PRIM has the priority to operate AP(s), FDs and A/THR.
If the Master PRIM loses the best operational capability, the engaged AP, FDs and A/THR do not disconnect. They are transferred to the Slave 1 PRIM, and:
- The Slave 1 PRIM becomes the Master PRIM
- The two other PRIMs become Slave 1 PRIM and Slave 2 PRIM.