Originally Posted by
Leonakua
So this has been unclear to me. On TakeOff, with both in TOGA, say NUMBER TWO fails. Not yet at V1, PF retards both levers, number two because he/she knows it has Failed, and number one because he/she rejects the rotation ..
Assuming each engine is isolated from the other, Including TCMA, will both shut down independently, and "simultaneously"? Even though engine data is read as quite different?
Each FADEC sees the thrust lever for its engine retarded, and will thus send its engine to idle.
IF the N2 for the engine fails to go to idle, AND the aircraft is on the ground (and slow enough?), THEN clearly the FADEC has lost control of the engine (something broke), and TCMA will cut fuel to the engine. It'll be hard for the aircraft to brake if the engine thrust does not reduce, and likely depart the runway to the side, too, so the role of TCMA would be beneficial if the conditions for it to trigger are met.
If TCMA did not trigger, then the FADECs retarded the turbines to idle as commanded.
Nothing in this process requires the right and left side to communicate with each other.