A320 question on severe damage (engine)
 

Dear all

I request you all to help me with this clarification.

What does A320 FCTM mean by:
The flight crew can suspect engine damage, if the flight crew observes two or more of the following symptoms:
-Important mismatch of the rotor speeds

What does Important mismatch of rotor speed mean ? I understand the meaning of no rotation however what does mismatch of rotor speed mean ( IMPORTANT MISMATCH-- to be precise )

Thank you for your help
Overhead

There is a non-linear, environment depending general relation between N1 and N2 in a working engine; two same-type engines under the same operating conditions will show roughly the same figures. So if You find one engines N1 to be much lower than expected with a given N2 while the other one shows normal figures, this might well indicate something wrong with the engine. This will often go together with high EGT, as a low N1 will do things to the general mass flow through the core engine, although this value may or may not be above the red line initially.

The other possibility, high N1 with relatively low N2, is likely less probable; maybe some tachometer issue may be involved.

Thank you so much Tu.114 for the wonderful and easy explanation

I think "IMPORTANT" means "SIGNIFICANT" in airbus-speak.

Got it , Thank you !