Originally Posted by
212man
Do we really mean N1? N2 governing is what our day to day existence is based on. N1 governing just ensures the engine keeps running after the start sequence is completed.
Yes, it is the quickest indication of what the engine is doing. N2/Nf is what happens AFTER the gas producer does its thing.
Try whacking a throttle open (acceleration check on a PT6 or T58 for example) and see which moves first - N1/Ng, ITT/T5 or N2/Nf. On some engines N1/Ng and temp will move almost together, but on all engines Nf moves slowest.