A320 Ditching - Both engines out - What Electrics and what Slats/Flaps can deploy ?

[wileydog3]

Herbert 23

@ wileydog3: of course it is possible that the APU was running.

Possible but not probable. And in all the departures (heavy or light) I did out of LGA we NEVER did an APU bleed. In fact, I NEVER flew a dept using APU bleed on the -320. The 737.. yes. -320.. no.

FYI, the runways at LGA is 7000ft. It is more than sufficient for max weight departures.

[herbert23]

I can sign that: possible but not probable. But I did takeoffs with APU running on both 737 and presently on the A32x. We allways try to get the flex a little bit higher.

[FlightDetent]

Originally Posted by herbert23

not for fuel saving but for increasing flex temp to reduce the possibility of an engine failure. also reducing maintenance costs. packs on apu or off increases flex temp around 3 degrees.

Never did I say that FLEX reduces fuel consumption. In fact I am led to believe that opposite is true, however is that irrelevant to our topic.

I do agree that more flex is better, or better phrased any flex is good flex. In your assumtion you speculated that the departure could have been with apu on to enable higher flex. In my opinion, this simply makes no sense (such as that APU fuel burn would offset any maintenance savings you speak so fondly about, ...). manufacturer retains this option (packs on APU) for extremely hot conditions (not the case), or a leftover for those not retrained thoroughly from 737 habits.

Interestingly enough, I attempted to check some data and our calculations also do not match.
I loaded 155 pax and 3 tons for bags / cargo and get ZFW of 60,3 not 58.
with 8 t fuel just to remain comparable, TOW is 68,2 i.e. still below max structural by almost 7 t below max. As I do not have KLGA in my database I had used LGKR / Corfu, one of my network most obstacle ridden departures and shortened the runway to 2100 m. 6 knot tailwind, 40 deg C, Q990hPa. Still: Conf 3, 45 flex (27,5 k engines) V2 132.

For ISA conditions and your weight the calculations is still flap 3 V2 132, but flex 54. Naturally all calculated with packs off.

Packs off is a good idea also for me. Packs on APU make no sense.

[misd-agin]

EMIT - U.S. standard departure is CLB power and clean up starting at 1000'.

Europe is 1500' and 3000'.

[IcarusRising]

I was gong through the ditching procedure after engine power failure and found it to be too cumbersome and time consuming in a similar situation. Airbus needs to revise the QRH procedure right away or add one to cover such a drastic case.

[herbert23]

we have 25k engines on our 320. just calculated the performanse in Corfu with your data (40 degress, 6 knots tailwind and so on). MTOW in corfu with our performance is 57,4, TOGA, flaps 2 and V2 of 132. (rwy length not shortened) Quite a difference.
I also think that most probably the APU was off. But having the Apu on from engine start until after takeoff consumes approximately 20 kg of fuel (if it runs for 10 minutes or so). That makes 10 euros. In my company supplying the packs via the APU is the prefered method instead of switching the packs off for 2 reasons.
1: improved ventilation of the cabin (better than solely via the cabin fans)
2: switching the packs on after thrust reduction can be pretty uncomfortable for the passengers
That is worth 10 euros for us. Service and pax comfort is more important for us than saving fuel or money (not a LoCo)
Let´s wait for the report but once again I also think APU was off but could have been on.

[wileydog3]

Icarus said

I was gong through the ditching procedure after engine power failure and found it to be too cumbersome and time consuming in a similar situation. Airbus needs to revise the QRH procedure right away or add one to cover such a drastic case.

No we don't need another checklist entry (Planned Ditching/UNplanned Ditching). The crew proved they can think and deal with a very unusual situation.

We will not be able to 'procedurize' (to use the popular word here in the States) everything. Were we to add items to checklists after every accident or 'drastic events', we would soon be taking out 3-5 rows of seats just to accommodate the additional weight and add a third crewmember, the FL (Flight Librarian).

[OKFINE]

To start or not start APU? If the decision to not start is predicated on using precious battery power/time, I offer the following: WHOGAS on a six minute flight in relatively good weather and daylight conditions. Am I missing something?

[PGA]

In EMER ELEC CONFIG you'll only have AC / DC ESS.

I was wondering if the characteristic speeds, i.e. GD / S / F / VLS etc will still be displayed on PFD 1 ?

[wileydog3]

Herbert 23... the WSJ is now reporting the APU was running but it does not clarify whether it was running during takeoff or was started after the bird strikes. I would imagine it was started as part of the dual engine failure checklist.

[electricdeathjet]

Stupid question, but dont you loose both main hydraulics if you press both fire push buttons????
Does the APU give you any extra hydraulic power??
Does it really matter if they started the APU in flight if the flight is going to last 3 minutes?
What is the point of this thread?

[Dan Winterland]

Yes you do. But in the US Air incident, the FO spent his time trying to relight both which indicates they hadn't done the failure drills.

[Metro man]

1. Pressing the fire button will cut off the engine driven hydraulic pump, but there is an accumulator in each system which will retain some pressure.

2. APU Will give electric power, therefore Yellow system electric pump and PTU will give the Green system.

3. Remember the British Airways flight which flew through volcanic ash and lost all four engines. The crew did everything they could and didn't give up, they got back on the ground.

4.Point of the thread, could he have done things differently, what would I have done in that situation, what can we LEARN from this.

Now a question from me, QRH hydraulic architecture diagram shows Blue system supplies Flaps, yet FCOM 3 states loss of flaps in this situation. Are the demands on the Blue system too great to supply the flaps as well so the priority valves isolate them or is there another reason ?

[strobes_on]

This what I believe is available:

AC and DC ESS busses. FAC 1 will display characteristic speeds on no 1 PFD. SFCC 1 is powered.

As far as slat/flap operation is concerned: SFCC 1 will operate BLUE system for SLATS. Residual hydraulic pressure of an idling engine should run the FLAPS slowly through the GREEN system and SFCC 1.

[FlightDetent]

herbert23: The different rating may explain much of the Flex difference, otherwise it is down to specific OEI procedure and precision of the calculation tool (I used RWY17). Needless to say, we both are in agreement that it depends on company requirements (apologies as I was rather stubborn explaining the reasoning behind ours), irrelevant to the thread, and there be much more to learn from the report than US Airways pack policy.

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Here's the theoreticalappropriate ditching abnormal C/L for 320-214:
.

But even with 100% hindsight and time the flow is really overkill. ECAM first, stop as ditch is imminent. Locate Ditching in QRH, read the fine small print to find out it should not be used, go to ENG DUAL FAIL (fuel remaining). Work through or skip the restart attempts and on page 5 the procedure I copied. And of course, the vital "11 degrees pitch" is yet again - in small print.

FD (the un-real)

[Artificial Horizon]

Initially you will NOT have the characteristic speeds displayed, however by recycling the FAC1 pushbutton after entering the emergency elec config you should be able to recover all these speeds.

[HOVIS]

Good thread this.

Question, my limited knowledge of the 320: There is a seperate APU battery. Can you dispatch under MEL with APU battery/charger inop and hence APU inop? Or is the APU battery essential to the emergency electrical redundancy power requirements?

I only ask as it occurs to me that if an APU start is attempted after a dual engine failure, will it really effect the DC elecrical power available for the rest of a very short flight?

Thanks in advance.

[Rick777]

The A320 has two batteries which are both aircraft batteries. They both also start the APU. They are also the backup power for the ADIRS., This is different from a Boeing which has a seperate APU battery. Both batteries and associated charger are required.

[TURIN]

Partially correct.

The 320 only has the 2 BATs.

330/340 has a separate APU BAT.

From my sketchy memory of big Boeings IE 747-400, I thought the APU BAT also was part of the emergency backup system and was a no-go. Could be very wrong there though.

Apologies for thread drift.