Thank you Nepo, and all.
Nepo, your explanation makes sense. You are engineer, so you are sure there is no sensor around the pipe.
In this case another question comes my mind. FCOM ECAM states :
FUEL ENG 1(2) FEEDLINE BURST
LAND ASAP (AMBER)
ENG 1(2) FAIL
,,,,,,,,Then the other steps on the ECAM
So, ENG FAIL will not necessarily occur with this ECAM, because as per your explanation, some part of the fuel is still fed to engine.
And, in AirTransat incident, as far as I understand from NAT GEO Air Crash Invest video, pipe completely ripped off, however engine was still running. So is there more than one Engine Fuel Feed line to keep engine running?
Thanks you if you can answer.