A320 One Engine Taxi - Engine Fire Protection

[Gallinazo]

Hello all,

Please forgive my (possible) misinterpretation or lack of understanding, first off.

Regarding the A320 OE Taxi, there is a comment in FCOM Supplementary procedures that goes like this;

Apply normal "AFTER START" procedures, but:
- Keep APU running to supply engine fire extinguishing, avoid electrical transients and allow the galley operation.

I can quite understand the second and third "reasons", but I do not get the engine fire extinguishing bit at all. There is no further qualification that I can see in the FCTM, either, on this subject. Looking at the FCOM electrical supply for Fire Protection, I get;

Engine fire loops on DC2 & DC ESS. Engine squibs on HOT 1, HOT 2 & DC2. Far as I know, these buses are available with Engine 1 started and the APU or APU GEN - OFF, and therefore fire extinguishing is supplied to both engines, anyway, regardless of APU.

Can anyone please state exactly what the APU is supplying to the engine fire extinguishing?

Thanks in advance, and sorry if this has been covered before, but I found no current threads which included it.

[NigelOnDraft]

Taxiing on Eng 1, Eng 2 & APU shutdown.

Eng 1 catches Fire and is shut down.

Do you still have the busses you state above for Fire Extinguishing?

Just a guess...

[mcdhu]

On battery power, only shot 1 will fire.

[Gallinazo]

OK, thanks. Makes sense, and gives me at least a couple of other things to revise with that in mind.

[screwdriver]

Bleed air supply for cranking engine if it has an internal engine fire?

[Gas Bags]

MCDHU has it. Engine bottle 1 squib A is powered by DC hot bus 1, and squib B is powered by DC hot bus 2. Engine bottle 2 has both squib A and B powered by DC bus 2. When down to battery power only DC bus 2 is lost so you can't fire either squib on engine bottle 2 if you need to.

[LEVEL600]

Apologize, but power supply for engine squib not suplied from hot battery bus looks for me very unusual, even if for bottle No.2 only…but airbus surprise me each day

[vilas]

I think screwdriver is correct. If engine 1 has to be shutdown and has internal fire you need bleed source to crank.

[Bubi352]

Is there any chance someone can pm a copy of the reference page document? Thank you in advance.

Apply normal "AFTER START" procedures, but:
- Keep APU running to supply engine fire extinguishing, avoid electrical transients and allow the galley operation.

[BM2]

Sorry to bring this old thread up, but I was having the same doubt and ended up here. And I came to the conclusion that the problem here is electrical distribution (as some guys mentioned earlier) rather than having a bleed source to ventilate the engine.

The SOP After start proceedures are different for the A320 NEO and CEO. The note

Keep the APU running to supply engine fire extinguishing

is only for the CEO models.

So having a look at the ELEC EMER CONFIG SYS REMAINING on both QRHs it is possible to note that:
For the CEO models on “batteries only” configuration, only the number 1 squib remains available for ENG 1.
For the NEO models both ENG1 squibs remain available in batteries only config.

So that’s it. Regarding fire protection you should keep the APU running when taxiing single-engine so you can have both squibs available in case of ENG 1 FIRE on the CEO planes.

[pineteam]

Originally Posted by BM2

For the CEO models on “batteries only” configuration, only the number 1 squib remains available for ENG 1.

Thank you for the updates.
Interesting thread, until today I did not really understand the reason behind it.
Could you confirm that bottle 1 ( squib 1) is available for both engines on battery only for the CEO models?

[BM2]

Affirm. When on batteries only you have Bottle 1 available for both engines on the CEO models.

[alexh1987]

Originally Posted by BM2

Affirm. When on batteries only you have Bottle 1 available for both engines on the CEO models.

But there are also some new CEO aircraft where both bottles are available on batteries only. I heard it‘s an option you can buy or refit.

[BM2]

Originally Posted by alexh1987

But there are also some new CEO aircraft where both bottles are available on batteries only. I heard it‘s an option you can buy or refit.

Nice to know that!

[J.L.Seagull]

Absolutely! The Airbus term for this mod is SETWA. Single Engine Taxi Without APU.

During the Emergency Evacuation drill, pre-mod aircraft will only have only one squib light illuminated once all Fire p/b's are pushed.

SETWA aircraft will have both squib lights on.

This is an interesting gotcha for us, as all our aircraft are modified, but our Sims aren't! Pet question from our TRIs!

[Its Maui]

Seagull, any chance you have a reference for that or a document?

Thanks

[Dualinput]

Seagull is correct...SETWA (single engine taxi without apu) is available from Airbus....

[pineteam]

Originally Posted by BM2

Affirm. When on batteries only you have Bottle 1 available for both engines on the CEO models.

Thank you.

Originally Posted by Its Maui

Seagull, any chance you have a reference for that or a document?

Thanks

https://services.airbus.com/upgrade/...xi-without-apu