A320 Electrical Smoke Procedure

[Flo121142]

Hi,
I'm just preparing for my A320 LPC and read again trough the smoke procedure. It advises you to consider setting ELEC EMER configuration if you suspect electrical smoke or are unable to determine the smoke origin. This way you might be able to stop smoke generation and you should be able to restore all systems prior to landing, except IR 2 and IR 3 (which are lost 5mn after setting ELEC EMER config). According to the list in QRH you need at least two IRs to do an autoland, therefore you loose this capability, which might be a very valuable option if the ELEC EMER config didn't remove the smoke (it would be far easier to do an autoland than doing a manual approach and landing in a cockpit environment filled with dense smoke with hardly any visibility). I found out that there is a way to retain IR 3 in ELEC EMER config by putting the ATT/HDG switch on CAPT 3.
Now I wonder why this is not considered by Airbus? Are there any reasons which might make this selection undesirable?
Perhaps there are some expirienced guys in here which might shed some light on this matter. Thanks for your help.

[Cough]

I guess the one downfall is if its ADIRU 3 thats generating the smoke - Remember the aim is to shut as much down as possible to remove potential sources of smoke...

Other than that, its quite a good idea. I have in the past tried to ATT align ADIRU 2+3 in ATT mode after the main gens are reset - but thats not good enough for autoland (according to sim fidelity!)

[vilas]

It is possible that because transfer is used instead of IR1 IR3 is supplied. In that case IR1 may be shed. With dual IR fail you won't have the autopilot.

[airbus_driver319]

Remember Airbus don't tell you to put the aircraft in emergency electrical configuration, they merely provide it as an option.

It is for the Captain to decide the best course of action, taking into account the full circumstances of the situation.

[Fly3]

In the emergency electrical config both Rad Alt's would be lost and therefore autoland is not viable even if you can get the auto-pilots back.

[Cough]

Fly3 - Thing is you restore normal electrics just prior to landing...

[Fly3]

But the problem is that you will be engaging autoland very late in the approach and that has led to disaster in the past.

[alvesjorge]

Once an ADIRU is disconnected, it takes a minimum of 7 minutes to fully align. The AC must not be moved while alignement is acquired. Therefore, restoring normal electrics prior to landing, even 15 minutes before, would get your LRRA's back on, but not the ADIRU's. And these would get damaged in the attempt.
Thus, no autoland

[Flo121142]

@alvesjorge: my original proposal did not talk about realigning the IR in flight as it is impossible in flight, as you correctly mention. The thing I propose is to keep the IR running while in ELEC EMER config, so you never loose it and when you restore the GENs before landing you will have autoland capability.
@fly3: valid point. Anyway, assuming an ILS intercept at 10nm and assuming you restore the Gens around 1mn before intercept you will have the Gens running for roughly 6mn. Airbus does not give an exact time when you should restore the Gens but that it should be done "a few minutes before landing" and before gear extension. I think its up to the PIC to decide if 6mn are too early or justified, considering the actual situation.
@vilas: According to the FCOM this shouldn't happen, at least it is mentioned nowhere. But perhaps they just forgot to mention it or didn't mention it for some reason. If I have some sim time left after my LPC I will try it in the sim and see how it works out.

[Cough]

Alves - What flo proposed means that you retain two ADIRU's in a fully aligned state...

Fly3 - If you can't see the instruments due smoke (let alone outside) then the end result of that is?

Just so everyone is clear. I am an SOP man, so I would follow the checklist and do it according to SOP's. However, I just see technical merit in what flo has written.

[Sky Wave]

I think villas may have it correct.

I wonder if the old wives tale about selecting IR3 to avoid a direct law landing has been misunderstood.

I suspect that the way to achieve this is to switch the selection between IR1 and IR3 and back every 4 minutes throughout the smoke drill so that neither IR1 or IR3 exceed 5 minutes without power. If that is the case the smoke drill is busy enough without trying to remember to switch IR selections every 5 minutes.

It's just my guess and it may be that both IR1 and IR3 remain supplied in which case the only thing I can see against doing that is as Cough says, it may be ADIRU3 that's smoking. We'd need an engineer with a wiring diagram to advise if the IR switching isolates IR1 when selecting IR3 to Capt.

[vilas]

Sky Wave
It is recommended to switch off IR2 and 3 to save battery life means these 5 mts IRs are supplied by battery then EMER gen is connected to either IR1 or IR3 if switching is used. Now when you play with IR3 and IR1does the other one goes to battery? If so then you are reducing the battery life which is some 23mts or so. If EMER GEN now packs up you are in serious trouble. What would you prefer Direct Law or Mechanical Back up. I some how cannot agree that armed with FCOM and FCTM a line pilot is smarter than Airbus Industry who have the hardware, software and all testing facilities and test pilots. Trying or making your own procedures in FBW aircraft you are asking for trouble. Frankly if anyone is avoiding direct law means he doesn't know why the aircraft goes in direct law. What else? Alternate law will mess up your landing.

[alvesjorge]

By head, and I don't work like that, only 2 of the 3 ADIRU remain on the bat for 5 minutes, and reselection of the indication does not interfere with the pwr sts of the units. It goes only to DMC level, not ADIRU. Subject to confirmation after I check the schematics, ok?

[A4]

My understanding is this.

"Normal" EMER ELEC CONF - IR1 powered, IR 2 & IR 3 on BATT for 5 mins then depowered and lost hence double IR "fail" on reselection of GENS so ALTN LAW to DIRECT LAW.

Switch ATT/HDG to CAPT 3 and IR 1 remains powered in the background and IR 3 remains powered. IR 2 to BATT for 5 mins then lost.

Selection on GEN LINE 1 and GEN 2 prior to LDG GR DN results in retention of NORMAL LAW as only IR 2 is lost and hence CAT 3 SINGLE - i.e. AUTOLAND.

This works in the sim. I imagine Airbus don't publicise this because the idea of EEC is to get rid of as much non essential electrical load as possible and the lawyers have would have a field day if the procedure wasn't followed and something untoward occurred.....:ouch:

[Sky Wave]

VILAS

You may have mis-understood me. I'm not a fan of selecting IR3 in order to avoid a direct law landing. I was trying to make sense of this old wives tale as I've heard it from several people.

If Airbus don't ask us to do it during the smoke proc then I'm happy that there must be a good reason and therefore I don't start experimenting.

[Sky Wave]

Thanks A4, that makes sense.

[vilas]

Sky Wave
Sorry I misunderstood you.

[vilas]

A4
I will try it out in SIM 1.8 STD and come back.

[Mäx Reverse]

While it is technically possible to retain IR3 under Elec Emergency Configuration by setting ATT HDG to FO3, the Pitot and Static Probes of System 3 (and 2 as well) will loose the de-icing capability. Thus while flying in icing conditions one might end up in an Unreliable Speed Scenario with Smoke on the Flight Deck and serious time pressure. No thanks.

So the only way for Airbus to offer use of this 'dirty little trick' to the crew would be to ensure in an early state of a complicated QRH procedure an during a demanding situation that absolutely no icing conditions are expectet from PPOS all the way until touchdown at the diversion airfield.

The Smoke-Procedure is already complicated enough and lot's of procedural mistakes happen without another biggie option as described above.

[A4]

That's a really good point Mäx.....without wishing to muddy the waters even further and I don't have FCOM's to hand, does switching AIR DATA 3 retain the de-icing on SYS 1 (Capt) ?