I was under the impression that if a fire loop is damaged it will annunciate as if it were a fire.
Mechanics on here please set me straight
We generally have 2 types of loops, the salt type that if damaged will generally open the circuit giving a fault, if center conductor grounded to outer case will gave a fire light indication and normally you need a 2ND loop to give a full warning. "the salt melts and allows for conductivity"
The 2ND and most common type of modern loop relies on gas filled tubes that have pressure switches, high press = fire, low pressure =failure and once again you need both loops to go high pressure to get the full on lights and bells warning.
In my experience 2 failures will not give a fire warning, you understand you now have no way to know if your engine develops a fire and operate by SOP or Captains discretion.