A320 - EMER ELEC CONFIG with blue hydraulic loss

[David Horn]

Unlikely, I know, but what happens if the A320 drops into the emergency electrical configuration when the blue hydraulic system is lost (through fluid loss)?

I assume the RAT will still deploy but not do anything (so RAT & EMER GEN FAULT light comes on), and the aircraft is running on battery power only, with all the unpleasant consequences that this entails.

Nothing in the FCOM about this short of a red "LAND ASAP", which is kinda obvious. ;)

[Che Guevara]

Nothing in the FCOM about this short of a red "LAND ASAP",

How about Flight on Bat Only (FCOM 3.02.04), if you use the Airbus books.

[David Horn]

Hi Che,

Not in my FCOM, don't have an "04" in the Abnormal and Emergency section. If yours is electronic, any chance you could copy-n-paste the relevant bit?

[fredgrav]

Hi David Horn,
ELEC EMER CONFIG (2 GEN OUT) + BLUE HYD SYS OUT/EMER GEN OUT = who's gonna power the FLT CTLS ???! :confused: FCOM 3 does not consider the situation above as no procedure may help you solve the problem ...

fredgrav

[hetfield]

who's gonna power the FLT CTLS ???!Oh my God it's 15 years ago, but AFAIK Green and Yellow....

[David Horn]

Yeah, you still have green and yellow hydraulics but presumably once your 22 mins of battery power is up you're on mechanical backup.

[fantom]

Waddaya talking about? G+Y are engine driven pumps not electrical !

[fredgrav]

Yep yep sure ! :ok: a few days ago was reflecting on how could the situation be this way: DUAL ENGINE FAILURE + BLUE SYS OUT ... that's why erroneously associated 2 GEN out with 2 ENG failure, thus thought of FLT CTLS left umpowered.

Did anyone analize how to cope with such an event ? ...

[TyroPicard]

fredgrav
Glide fast enough to have windmilling hydraulics on G+Y for flight controls.
Forced landing/ditching before the batts fail.

David Horn
Abnormals/emergency drills assume everything else is working.. you will have to figure it out yourself from the available references...

QRH 1.01 ELEC EMER CONFIG SYS REMAINING has a column for BAT ONLY in flight... big picture stuff:
FLY .. PFD 1, IR 1, ADR 1, ISIS
NAV .. VOR 1, ILS 1
COM .. VHF 1
I'll leave you to figure out stuff like Landing Gear...

Yeah, you still have green and yellow hydraulics but presumably once your 22 mins of battery power is up you're on mechanical backup. True - but here's something to investigate.. can you control the engine thrust with dead batteries?

[vapilot2004]

True - but here's something to investigate.. can you control the engine thrust with dead batteries?

As far as I know, most modern FADEC controlled engine types will keep running if main, standby, and emerg busses are lost. Engine driven pumps keep the fuel coming - spar valves are motor driven, therefore not held open electrically. The FADECs are powered by engine-driven dedicated generators.

The only glitches would be in icing conditions since the igniters would be unpowered and also full thrust situations where the engine driven pumps may not be able to keep up with the demand.

[catiamonkey]

In fact, all the (transport) FADECs I've seen disconnect themselves from ship power once power from the PMG/alternator is good. Done that way to keep a surge or other electrical problem from taking out engines. So if it was running fine when you left, the engine should continue to run without batteries.

[Microburst2002]

Of course the engines run. As they do in a Seneca.

But all computers are lost, after batteries are depleted, and therefore you are in mechanical backup, with rudder and THS hand wheel. Try to land like that with no flaps no slats...

suggested procedure:

1- pray to god in all possible ways (christian, muslim, jewish...)
2- if you have fuel, try to learn to fly that way for a while
3- find a looooong runway with no crosswind
4- prepare the go around
5- consider changing the CG (without causing pax panic)
6- pray again and do the approach. good luck!

[fredgrav]

Glide fast enough to have windmilling hydraulics on G+Y for flight controls.

Hi TyroPicard,
can a windmilling engine draw its own EDP (engine driven pump) ?

[Permafrost_ATPL]

What powers the signals sent by the thrust levers? In other words, if your batteries have run out of juice in complete elec failure, do the thrust levers still send an input to the FADECs?

P

[rudderrudderrat]

Hi fredgrav,

can a windmilling engine draw its own EDP (engine driven pump)

Affirm. In the sim, when you've had a simple engine run down and secured it with Thrust Lever Idle and Eng. Master switch off. (So the Fire Push Button has NOT been pressed) - then the hydraulics from the wind milling engine are good at some speed above green dot.

[hetfield]

- Both engines out
- BLUE HYD Gone
- One wing fell off

"Start procedure!"

[fredgrav]

Thanx rudderrudderat,
was very doubtful to be honest ... ! ;)
**********
Hi hetfield,
what do you mean with "one wing fell off", we just have the remaining one as a backup ! :ok:

[Meikleour]

My understanding is that the FADECs are self powered electrically provided the N1 rpms are high enough ( I forget the figure 6% ??)

[fredgrav]

Hi Meikleour,
the FADEC is self-powered above 15 % N2 (FCOM 1.70.20 p.5) ...

[Hydroman400]

fredgrav, from EDPs I know of, enough pressure and flow can be delivered down to low levels of N2 (e.g. below 10%)- hopefully enough before the RAT powers up. This is usually part of the info needed to demonstrate compliance with 25.671 (d). However, annoyingly the FADEC auto EDP depress (on some engines) can throw a spanner in the works.

[fredgrav]

Hi Hydroman400 !
Do you know what engines (for Airbus) have an EDP auto-depress function ?

Thanks in advance

[vapilot2004]

What powers the signals sent by the thrust levers? In other words, if your batteries have run out of juice in complete elec failure, do the thrust levers still send an input to the FADECs?

Yes Cap Permafrost. The power for the resolvers comes from the EEC/ECC computers which are powered by their own dedicated small generator separate from the IDG gearbox.

[TyroPicard]

Microburst 2002
Try to land like that with no flaps no slats...
suggested procedure:You should have started with the simplest possible solution: Fuel permitting select Flap 1 before the batteries are lost.. CONF 2 or 3 would be even better.

Of course the engines run. As they do in a Seneca.Thank you for your patronising response. I know that, but I don't know if the OP David Horn does, so I posed it as a question for him. But we seem to have frightened him off....

[Microburst2002]

Didn't mean to be patronising Tyro, and certainly not with you.

I just did too fast a reading and read some stuff explaining why engines run with batteries out. I thought this was not necessary here. Hence my coment.
At least, I did not include a smiley bumping its head against the bricks...

I guess it made me remember a student pilot of mine, who in his second solo had an alternator failure. he landed normally and was excited because he was scared of the engine flaming out. I gave him homework inmediately, and asked him how on earth had he passed the ground school exams.

Of course, going to CONF 3 before batteries deplete is a good thing to do, not covered in any FCOM by the way. And it is very unlikely that increased fuel consumption will make it non advisable. Even if you are in the most critical point of an ETOPS flight, you can wait 25 minutes to lower the flaps while descending to 20,000 towards the nearest suitable alternate. The reserves would suffice (fuel burnt approximately twice)? I guess it would.

[David Horn]

Tyro - nope, still here! :-)