Airbus Dual Eng Fail procedure question
 

QRH 70.01 Dual Eng Failure:
Why the reset of FAC1?

Happy Landings boys,
CC1

When AC busses fail FACs fail. On EMER GEN only FAC1 is available after reset. Why do we need it? Because right aileron is not hydraulicly supplied so it floats causing roll which can be trimmed off by rudder trim

Hi vilas,
On A320 series, both ailerons are powered by the Blue system. What aircraft are you referring to?

Rudderrudderrat
I am referring to A320. Check PRO-ABN-70P31/54 below FAC1---OFF THEN ON

vilas
Both L & R ailerons are powered by G & B
With the RAT deployed, Blue Hyds available.
Please explain why you think the right aileron would "float".
Thank you for explaining how to reset a FAC.

rudderrudderrat
It is not my thinking I have given you a reference which is in black and white. Kindly refer to that. Blue and green supply ailerons normally but in dual flame out green is lost and blue when driven by rat only produces 2500 psi. That could possibly be the reason. mind you only right aileron is shed.

vilas,
Post #12 from G & Y Hyds Failure. I certainly hope you are not teaching that sort of misinformation.
Where does it say so?

About aileron shedding I have quoted Airbus manual. I do it again for you. PRO-ABN-70 P31/54 You check and get back. And about G+Y what I quoted is 100 percent correct. you can check that also and offer your views.

Good knowledge,Cheers gents.
Aileron possibly to do with Elac2 u/s?just a suggestion.
CC1

vilas,
Thanks for the reference, and you are correct - it does say when the hydraulic power is lost, the RH aileron will float - but I have no idea why that is so.

ELAC 1 controls the blue actuator on the LH aileron and the green actuator on the RH aileron. This means that if no green hydraulic pressure is available, the RH aileron is inoperative as the blue actuator is in damping mode. Some floating may occur.

It has nothing to do with RAT pressure or an aileron being 'shed'. It is simply a result of system architecture.

The ability to quote manuals does not necessarily indicate system understanding, it seems.

ELAC 2 standby supply on HOT2?
 

Hi guys!

One thing, I do not quite understand about the whole issue is why ELAC 2 is unservicable in Elec Emer Config?

Checking the bus equipment list, gives DC ESS for ELAC1 and DC2 for ELAC2 in normal circumstances. I can understand that if this was the only supply, ELAC 2 would be U/S with a Dual Eng Fail, as DC2 is gone.

However, the bus equipment list also gives HOT1 for ELAC1 and HOT2 for ELAC2 as "standby supply". The HOT busses are directly connected to the batteries, so they are always powered until your batteries are flat.

Shouldn't the ELAC2 continue living of the HOT2 bus for the remainder of the flight (and control the RH aileron via the blue Hyd), even with the aircraft in Elec Emer Config? What am I missing here?

Thanks for your help,

Torsten

ELAC 2 is powered by battery 2 if normal power fails, but only for 30 seconds after which it is de-energized. This is presumably to cover a temporary loss of normal electrical power and to save batt 2 in case the loss is not temporary.

ELAC 2 is connected again to batt 2 when the nose gear is extended.

Awesome. Thanks for the additional info.

The reenergizing with the gear extended is to improve handling qualities in the approach?

Torsten

KBPSen
Thanks for your input. Let noble thoughts come from every where ( even with brickbats). May be you can answer my query about G+Y fail. You can see my post on this.

Y ELEC PUMP
 

Why ENG DUAL PROC does not require to switch on Y ELEC PUMP when APU is avail? We lost G and Y HYD SYS so can we recover HYD SYS by using Y ELEC PUMP? I asked you due to FCOM ABN HYD G+Y SYS LO PR asked:
 If yellow sys lost by ENG 2 PUMP LO PR:
YELLOW ELEC PUMP..................ON
And what does it mean "IF HYD NOT RECOVERED" in PRO-ABN-70:

STATUS page
.............
APPR PROC
 IF HYD NOT RECOVERED:
FOR LDG............................................... USE FLAP 3
?
So, can HYD SYS be recovered by Y ELEC PUMP or by airflow when windmill is good?
Thank you!

Hi Yurich,
In our simulators, with airspeed >about 220Kts, then the wind milling engines can keep the Hyd pressure OK.
If the APU generator is on line and Y Hyd pressure is low, ECAM asks you to turn the Y Elec Hyd Pump on.

In the absence of a QRH or FCOM here, I'm just wondering in what circumstances you would not want to turn on the yellow AC Pump (assuming fluid present) in the event that the APU generator was available? That Yellow-SYS pressure from the windmilling No. 2 engine ED Pump will decline as soon as you slow down for the approach.

Can you guys confirm that it is still policy to make one attempt at an APU start in the Dual-ENGINES failure case?

Hi Chris,
Affirm.
If there is fuel remaining, then QRH asks to attempt APU start when below FL250.
QRH does not assume APU Generator comes on line and hence procedure is worst case scenario.