Originally Posted by
SPUDO
Not quite, Buster15. The engine is not on "temperature control" but is being governed to maintain the N2 speed called for by the power lever angle (not "temperature control", but "N2 control"). This is what the Pilot Training Manual says, and is consistent with every other twin spool engine I am familiar with.
Half correct. The FCU is increasing fuel flow to bring the N2 back to "on speed" - not the temperature.
The Pilot Training Manual, logic and experience all say the N2 should stay the same (with everything else changing), but that is not what happens. The N1 stays the same and the N2 increases.
???
OK. All the engines I have been involved with have been temperature controlled.
The pilot lever angle normally demands a NH/N2 but the top limiter is JPT/TBT and NH/N2 can vary for a given JPT/TBT.
Anyway. A simple way of thinking about it is that NH/N2 equates to thrust/power demand..
When AI is selected the engine has to increase in speed slightly to maintain the same thrust/power for the same speed.
If not, the engine would produce less thrust/power for a given NH/N2.
Did you tell us what the N2 increase was. I would be surprised if it was more than 0.5%.