If there is any conflicting information, your FCOM shall be the overriding reference.

Please read the footnote at the end of this page.

Q1. How many fire loops are installed on each Engine and on APU?

A1. Two fire loops each are installed on the engines and the APU.

Q2. Where are the engine fire loops installed?

A2. The Engine fire loops are installed at :-

(a) One in Pylon Nacelle

(b) One in the Engine core

(c) One in the Engine fan section

Q3. If there is a fault in one of the loops, will fire detection be affected?

A3. A Fault in one loop does not affect the warning system. The unaffected loop still protects the aircraft.

Q4. You are cruising and you get ECAM caution of ENG 1 LOOP A FAULT. What did you lose? Is fire detection on ENG 1 available?

A4. ‘ENG 1 LOOP A’ is lost. Fire Detection is still available on Engine 1.

Q5. If a failure in both engine fire loops occurs within 5 seconds of each other, what will happen?

A5. The Fire warning will appear in case both engine fire loops fail within 5 seconds of each other (Flame Effect) .

Q6. When will fire warnings for engine be triggered?

A6. Fire warning for the engine will be triggered in the following cases :-

(a) A Fire signal from both loops A and B or,

(b) A Fire signal from one loop when the other is faulty or,

(c) Breaks in both loops occurring within 5 seconds of each other (Flame Effect), or

(d) A Test performed on the control panel.

Q7. If you get an ECAM of ENG 1 FIRE DET FAULT, is fire detection available for no 1 Engine?

A7. No.

Q8. How many fire extinguisher bottles are available for fighting an engine fire?

A8. Each engine has two Fire Extinguisher bottles available.

Q9. What action arms the engine fire extinguishing squibs?

A9. Pushing the ENG 1(2) FIRE P/b sends an electric signal which arms the fire extinguisher squib.

Q10. When you push Eng Fire P/B, what happens?

A10. When you push the ENG FIRE P/b , an electric signal performs the following for the corresponding engine :-

–> Silences the aural fire warning

–> Arms the fire extinguisher squibs

–> Closes the Low pressure fuel valve

–> Closes the Hydraulic fire shut off valve

–> Closes the Engine bleed valve

–> Closes the Pack Flow control valve

–> Cuts off the FADEC power supply

–> Deactivates the IDG.

Q11. How do you know that an engine fire extinguisher bottle has discharged?

A11. “DISCH” lights up Amber in the AGENT 1(2) P/b to indicate when the fire extinguisher bottle has lost pressure.

Q12. Why there is a 10 seconds delay in firing first agent in case of engine fire checklist in flight? Why there is no such delay if there is fire in engine on ground?

A12. The 10 second delay allows N1 to decrease, reducing nacelle ventilation, and thereby increasing the effect of the agent. [Automatic countdown on the ECAM].

Q13. If an APU start is initiated on battery power only, is fire protection available?

A13. Yes.

Q14. If an APU fire occurs on the ground, what must be done to shut down the APU and extinguish the fire?

A14. If an APU fire occurs on ground, the system shuts down the APU automatically and discharges extinguishing agent.

Q15. Is there any difference between APU fire on ground and in flight?

A15. If an APU fire occurs on the ground, the system automatically shuts down the APU and discharges extinguishing agent whereas in flight the crew have to manually shut down the APU and discharge the extinguisher.

Q16. How many fire loops are installed on APU for fire detection?

A16. Two.

Q17. How many fire extinguisher bottles are installed for fighting APU fire?

A17. One.

Q18. Can the APU FIRE test be performed with the APU running?

A18. Yes.

Q19. What external indications may be received in the event of an APU fire while on the ground?

A19. The following indications are received in the event of an APU fire while on the ground :-

On the External Power Panel


The Red APU FIRE Lt. comes on and an external warning horn sounds

Q20. Name the components of the APU fire detection system?

A20. The APU fire detection system consists of :-

–> Two identical Gas detection loops (A & B) mounted in parallel.

–> A Fire Detection Unit

The Gas detection loops consist of :-

–> One sensing element in the APU compartment.

An APU fire panel on the Overhead Panel in the Cockpit which has controls and indications for APU fire detection and extinguishing.

Q21. How many fire extinguisher bottles are provided for the cargo compartments?

A21. Two.

Q22. Is it true that the FWD + AFT Cargo has a common fire extinguishing system?

A22. Yes.

Q23. Explain cargo smoke detection system installed on IndiGo a/c?

A23. The cargo compartments have a smoke detection system.

–> Cavities in the cargo compartment ceiling panels each hold two smoke detectors. Each detector is linked to one of the two detection loops.

–> The forward cargo compartment has one cavity.

–> The aft cargo compartment has two cavities.

–> The CIDS receives signals from the detectors and transmits them to the ECAM, which displays a warning in the cockpit. The CIDS has two identical channels.

Smoke in one cavity activates the cargo smoke warning if :

–> Both smoke detectors detect it, or

–> One smoke detector detects it and the other is inoperative.

Cargo Ventilation, & the cargo smoke warning is activated in either compartment, the associated isolation valves automatically close and the extraction fan stops.

Q24. In case of FWD cargo smoke,

>Once you discharge agent 1, how will you know that 1st bottle is discharged?

>When do you have to discharge second bottle?

>When you discharge second bottle, what happens? How will you know that 2nd bottle is discharged?

A24. (i) When the Bottle 1 is discharged, the DISCH 1 Light comes on in Amber.

(ii) 60 minutes after the discharge of the first bottle, the DISCH AGENT 2 Light appears. The crew has to discharge AGENT 2.

(iii) The DISCH AGENT 2 light goes off when the Agent 2 squib is ignited. The DISCH 2 light comes on in Amber when the BOTTLE 2 is discharged.

Q25. In the case of an ECAM of SMOKE FWD CARGO BTL1 FAULT, what did you lose?

A25. In the case of FWD CARGO BTL1 FAULT , The bottle 1 is lost leading to the fire extinguishing capability being lost in the FWD (AFT) cargo compartment.

Q26. If a cargo smoke detector fails, does that render the system inoperative?

A26. No.

Q27. How many cargo smoke detectors must sense smoke to issue a warning?

A27. Smoke in one cavity activates the smoke warning, if, :-

–> Both smoke detectors detect it, or

–> One smoke detector detects it and the other is inoperative.

Q28. In case of an ECAM appearing for FWD CARGO SMOKE on ground, what is important to note?

A28. In case of FWD CARGO SMOKE warning on ground, with the cargo doors closed, order the ground crew not to open the door of the affected cargo compartment, unless the passengers have disembarked and fire services are present. Also ensure that the FWD(AFT) cargo doo is closed before discharging the Ext. agent.

Note: Expect SMOKE warning to remain after agent discharge, even if the smoke source is extinguished. Gases from the smoke source are not evacuated, and smoke detectors are also sensitive to the Ext. agent.

Q29. What are the indications of avionics smoke?

A29. One smoke detector in the air extraction duct of the avionics ventilation system detects smoke in the avionics compartment.

It signals the ECAM to display a warning in the cockpit.

When it detects smoke for more than 5 s:

‐ A single chime sounds

‐ The MASTER CAUTION lights, on the glareshield, light up

‐ The ECAM displays a caution on the E/WD

‐ The SMOKE light, on the EMER ELEC PWR panel, lights up

‐ The BLOWER and EXTRACT FAULT, on the VENTILATION panel, light up.

Q30. Does avionics compartment have a fire extinguishing system?

A30. No.

Footnote: Tremendous efforts have gone into making this page. People involved with Project Airbus Tech (PAT) have spent countless sleepless nights to make this page possible for you. The least you can do is to support us by giving us our due credit.

No part of this page may be copied, or distributed, or used for any commercial purposes. For any uses, please CONTACT THE FLYING ENGINEER.

Thank you for supporting us, and thank you for giving us our due credit.


  1. Humberto Nuche said:

    Very good page, very clear and helpful, congratulations to all involve on this!

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