Fire detection, loop breakage...
 

I'm confused with how the loop system works when a loop breaks giving a fault indication but yet once you select said loop off or both loops off the detection system still works..what am i missing. if it's a closed circuit how does the sytem operate. i'm refering to the sytem onboard airbus.

any help plz.

Probably the comma and period keys? Say what, now?

Abit rushed i know, sorry. Think it's still s clear question. Just want a brief explination...

Select loop off on Airbus?
Maybe "I" miss something?

If it's like the DHC6, this may help.

Short answer is that the system is a dual loop type.

If one loop breaks you still have a servicable second loop.

The logic of the circuit detects a break when the gas pressure in the loop drops. The 'loop' is a sealed tube containing a gas and a gas impregnated metal core. When there is a temp rise then the impregnated metal core releases it's gas and consequently increases the loop gas pressure. This triggers the pressure switch, indicating a fire.

If the second loop gas pressure also fails within 20secs? Then the logic assumes a catastrophic engine burst and detects a fire.

There is a lot more to this but I'm busy. Hope this helps.:ok:

So here is the Fireloop for Airbus A320Fam. (Without possibility of switching)
http://img137.imageshack.us/img137/9...loopyr8.th.jpg
.
...and the Fire Detection Unit FAULT-Logic:
http://img137.imageshack.us/img137/1...aultyp2.th.jpg
.
...and the Fire Detection Unit FIRE-Logic:
http://img137.imageshack.us/img137/9...firecg3.th.jpg
.
.
and here the Logic of the 737NG (With possibility of switching)
http://img137.imageshack.us/img137/3...tionhf7.th.jpg