The engine protection system is incorporated into the EEC. Its hardware performs the following functions:
LP and IP Rotor Overspeed protection...
Remember - In the case of IP rotor, apparently protection is provided
only for an intact rotor (my emphasis). If the IPT becomes detached, then the EEC
has no clue what the IPT is doing, since the phonic wheel is on the IPC shaft.
But as we have previously discussed, a rapid N2 unspooling without like N3 change is indicative of mechanical failure (e.g. IPT detaching), and there seems to be the potential to "catch" this in the software before destructive overspeed occurs. In QF32's case, there is an apparent six-second window.