AF330
The engine 1 and 2 button is to open the starter valve so that the air goes to the turbine starter. Right?
The fuel quantity to add is decided by the FADEC system by looking at the EPR to know the quantity. If you press that button it will add fuel by looking at N1, am I right?
Now I have read all these notes I am getting the idea....
1/ Yes, manual mode
2/ Yes, but....
The N1 button is not for starting. It's an Alternate mode function.
It's for changing the datum from EPR to N1 because possibly the FADEC engine control has a fault. The MEL will direct you to now use the Alternate mode setting by switching to N1 mode.