A320 Fire Protection Questions

The avionics smoke detection system consists of the following:

• A smoke detector, smoke detection control unit and one halon cylinder.
• A smoke detector, and smoke detection control unit.
• A smoke detector, heat detector, smoke detection control unit and one halon cylinder.
• A smoke detector, smoke detection control unit and two halon cylinders.

Explanation: The avionics bay has smoke detection only — one smoke detector in the ventilation extraction duct plus its control unit — with no halon extinguishing bottle at all, unlike the engines, APU, cargo, or lavatories.

Fire Protection - Avionics Bay (System Description, Smoke Detection)

DISCH light on either the engine or APU fire agent switches indicates:

• The APU or engine FIRE switch has been pushed.
• The extinguisher bottle has been discharged.
• A fault has occurred in the respective fire bottle.

Explanation: The amber DISCH light comes on specifically when the corresponding fire extinguisher bottle has lost its pressure — i.e. it has been discharged.

Fire Protection - Engines and APU (Controls and Indicators, AGENT PB-SW)

After depressing the CARGO SMOKE TEST push button once, a satisfactory test of the aft cargo compartment smoke detector consist of:

• Two complete cycles with associated warnings.
• Not needed as this system self-tests during the first engine start.
• One complete cycle with associated warnings.
• Three complete cycles with associated warnings.

Explanation: Holding the CARGO SMOKE TEST pushbutton runs the red SMOKE lights through two complete cycles (along with the associated ECAM warning and amber DISCH lights) as part of a single valid test.

Fire Protection - Cargo Compartments (Controls and Indicators, TEST PB)

Engine heat sensing are located in pylon nacelle, engine core and fan section.

• True.
• False.

Explanation: Each engine's fire-sensing elements are distributed across the pylon nacelle, the engine core, and the fan section.

Fire Protection - Engines and APU (System Description, Fire Detection)

APU fire detection is accomplished by:

• A two channel SDCU located in the APU compartment.
• Two parallel fire detection loops.
• One fire detection loop.
• A three channel SDCU located in the APU compartment.

Explanation: The APU, like each engine, is protected by two parallel fire detection loops feeding a Fire Detection Unit — not a multi-channel SDCU, which is the smoke-detection architecture used for cargo, lavatories, and the avionics bay instead.

Fire Protection - Engines and APU (System Description, Fire Detection)

Fire protection for the cargo compartments includes:

• Two fire bottles; one for each compartment.
• One single shot fire extinguisher for the aft compartment only.
• One single shot fire extinguisher agents which can be discharged to either compartment.

Explanation: The FCOM is explicit that cargo fire protection uses a single fire bottle with two discharge heads (one per compartment) feeding three nozzles — not two separate bottles — so the agent for either compartment comes from that one shared bottle.

Fire Protection - Cargo Compartments (System Description, Fire Extinguishing)

How many halon fire extinguishing cylinders are there per engine?

• Each engine has two fire extinguishers.
• Each engine has it’s own dedicated fire extinguisher and has the capability to share the other engine’s cylinder.
• Each engine has it’s own dedicated fire extinguisher and has the capability to share one centrally located halon cylinder.
• Each engine has one fire extinguisher.

Explanation: Each engine carries two of its own dedicated halon fire extinguisher bottles, each with an electrically-operated squib (and each squib on dual electrical supply) — engines don't share bottles with each other.

Fire Protection - Engines and APU (System Description, Extinguishing)

How many fire extinguishing bottles are available for fighting an APU fire?

• One.
• Two.
• One cylinder shared with the aft cargo compartment.
• Two cylinders shared with the aft cargo compartment.

Explanation: The APU has just one fire extinguisher bottle (fitted with two electrically-operated squibs for redundant discharge control) — it isn't shared with the cargo compartments.

Fire Protection - Engines and APU (System Description, Extinguishing)