Originally Posted by
ravill
Do we need to buy two of these for twins?
Ravill,
yes! Each CTU can be configured either as a "Master" or "Slave 1" to "Slave 3". The only difference between a CTU that is "Master" or "Slave" is that a master device sends down altitude and G force. The Master also takes care of the Autothrottle function if that is enabled.
All the slaves (up to 3) sends down only engine info and fuel info for the connected turbine.
So yes, you need one CTU for each engine (up to 4) in your plane.