Not quite. After the engine is started, the DECU only controls N1 once the N2 exceeds 9%. Which is why, if you start the engine with the rotor brake on and then move the ECL from IDLE to FLY, the engine stays at idle.
So you start with the rotor brake on and the engine sits there happily at idle N1 - what do you suggest is controlling that value?
And the other point. The DECU has no idea what the NR is...it doesn't even have an input for NR signal. The trigger for the DECU to govern N2 is when it senses the ECL in FLY position.
I didn't suggest it did sense Nr, but if you don't have Nr you won't have N2 and in normal conditions they are matched.
I was also talking in generalities about any governor, whether a FADEC, a DECU, an ECU or a hydro-pneumatic system using P3 air and bob weights. You start the engine and the N1 is governed then, as you increase the power the N2 increases and at a certain point it becomes the datum that is then governed.
The trigger for the DECU to govern N2 is when it senses the ECL in FLY position
Are you positive about that? In the S92 when you advance the throttles from IDLE to FLY the N2/Nr will rise and then reach the normal value of 105% at which point pushing the throttles forward further has no effect. This happens a couple of inches before reaching the FLY detent and clearly indicates that the FADEC has taken over N2 control. There also some flight checks that require the throttle to be retarded out of the FLY gate, but the N2 is still governed. It was the same in the 76A+ with its steam driven system.
(Note - I do know that in the S92 the Nf/N2 is referred to as Np, but was keeping it simple)