Wing anti-ice lost if eng fire p/b is pushed -why?

[Airbus Bloke]

Is it because you can't open the cross bleed due to pack contamination or something like that. FCOM is not helping. Thanks.

[noflynomore]

Not that.

Probably bleed air demand from the good engine is inhibited to preserve availability of max power.

[wiggy]

Wing anti-ice lost if eng fire p/b is pushed -why?

That's not a universal state of affairs so it would help if we knew which aircraft type ( guessing it's not Boeing by the "p/b" comment).

[PENKO]

If Airbus bloke is referring the Airbus 320 family it is indeed due to the crossbreed valve staying closed. As to why, looking at the procedure logic indicates the prevention of cross-contamination.

If the engine fire push button was not pushed, which means there was no damage or fire, then there is no problem running wing AND engine anti-ice from the live engine. Only limitation is that one pack needs to be switched off when using wing anti-ice!

[EI-PAUL]

Hi Airbus Bloke,

I suppose we are speaking about A320 here.
If this assumption is correct; when you push and release the engine fire p/b it sends an electrical signal that performs a lot of actions, among them also to close the engine bleed valve (DSC 26-20-20).

I may be wrong, but from my understanding of the system, if you just push the fire p/b you may still be able to use WAI opening the x-bleed and using one pack only when WAI on to avoid excessive load on the only remaining system.

The real point here anyway is: why should you release the engine fire p/b without discharging the fire extinguisher? If you decided to release the fire p/b, in fact, it means to me that you diagnosed an engine damage, so in this case you should release at least the first agent.
From now on than your assumption is correct: you can't use WAI cause the x-bleed must be shut for the rest of your flight to avoid air conditioning contamination. The use of WAI would ends up de-icing one side of the aircraft only.

[EI-PAUL]

Sorry PENKO, I didn't see your post as I was typing mine ...

[Chris Scott]

Wiggy,

The OP's pseudonym when joining last month might be a clue? ;)

The question isn't applicable only to Airbus twins, however. The wing anti-ice uses bleed air from the engine on the same side of the pneumatic cross-bleed valve, which normally remains closed. In the event of an engine being shut down you can cross-bleed from the other side. IIRC, however, you can use that for wing anti-ice OR the air-conditioning pack - not both.

If the engine shut-down is due to an engine fire on, say, the R/H side, would one want to allow bleed air to be exchanged with that engine? Presumably not, so the cross-bleed remains closed. As it would not be desirable aerodynamically to run asymmetric wing anti-ice, the whole system is disabled.

[EDIT: Oh dear, I see I'm third in the queue... Spent too long looking for my old QRH! :O ]

[wiggy]

The OP's pseudonym when joining last month might be a clue?

Fair cop, I was being a bit dull.

The question isn't applicable only to Airbus twins, however.

That might be true but TBF it most certainly isn't true for all twins, I know of at least one type where (providing there are no other problems with the bleed system) in the event of an engine fire, bottles fired, fire handles pulled and turned etc, the system configures to allow full wing AI both sides if needed and continued operation of both packs. The engine isolation actually happens at the engine fire wall.

I'm not trying to be over pedantic, just perhaps emphasising it helps if OPs are more specific when asking questions about exactly which type is involved( well, that's my excuse) :hmm::O

[Chris Scott]

Quote:
"... it helps if OPs are more specific when asking questions about exactly which type is involved..."

Hear, hear! No wish to pick on this particular example from a relative newbee, but many of our old hands could benefit everyone if they took more care in phrasing the title of any new thread, as well as the content of its first post.

[Airbus Bloke]

Sorry, forgot to say A320 family. Also I should have said that a squib would have been fired after the eng fire push button. Neither contamination or assymetric icing are desirable so pretty much what I thought. If only Airbus would produce a common sense manual!

[PENKO]

What is not common sense about it? If you do get ice, and I mean SEVERE ice accretion that won't melt away once out of cloud, now how often does that happen in Western Europe, the you descend (or climb if you must) out of the clouds and follow ECAM status advice: MIN SPD VLS+10/G DOT

Don't read more into it! If you do, you end up in no-man's land.
You could argue that if contamination is the only worry, then why not just switch off the packs and open the crossbleed.
But Airbus won't go so far so all we've got is that Airbus prefers ice+VLS10 over messing with the crossbleed if the fire PB is pushed. The rest is test pilot territory.

And by the way, according to FCOM it doesn't matter if the squib is fired or not: if ENG 1(2) FIRE pb-sw pushed.

[vilas]

Pack contamination doesn't tell the whole story. If you open the cross bleed then the smokes and fumes trapped that side will enter the aircraft and the hell will break loose because you cannot be sure whether this is from the existing engine problem or a fresh development. So you will end up doing Smokes Fumes Avionics Smoke drill which is a serious LAND ASAP. So not wise thing to mess up with a closed cross bleed.

[EI-PAUL]

And by the way, according to FCOM it doesn't matter if the squib is fired or not: if ENG 1(2) FIRE pb-sw pushed.

You're right, I've just checked the FCOM reference, thanks!