"FADEC looks to see if N2 <18%, (which will require a start assist) or N2>18% (will not require a start assist) and hence decides whether to open the starter valve or not."
This thread is pretty old but hopefully someone around that can help with this.
Regarding our aeroplanes with IVE engines there is a comment FCOM DSC MANUAL STARTING;
"In flight, the FADEC always commands a starter-assisted start"
This comment is not consistent with FADEC looking at N2 below or above 18% and commanding Start Valve open or not.
Can someone please comment on the significance of this.
In the NEO aeroplanes P&W engines this comment doesn't exist?
Does the same logic apply, FADEC looks at N2?
If so, what is this N2 value? Is it 15% as per the relight envelope?