A330 power transfer

[Romasik]

One of these days - no APU. GPU is connected via EXT POWER A. Following the recommended procedure starting ENG 1 first, then during pushback crossbleed ENG 2. As external power removed the entertainment system goes to reset for 15 minutes along with safety demonstration. WHF:confused: Next flight tried EXT POWER B - the same sh.t.
Haven't tried ENG 2 first or both engines before external power removal.
Something is wrong here. Recommended procedure and chaos with safety demonstration. Any idea, why and what to do?

[mono]

With just one electrical power source (not APU) The electrical system load sheds.

Typical shed loads with only one electrical power source are Galleys and IFE.

I would say what you experienced is normal and the only solution is to keep the EXT power connected until the second engine is started or no leave the IFE off and do a manual demo, switching it back on after the second engine generator is on line.

[TURIN]

Airbus also recommend that both A & B EXT PWR are connected when APU not available. Never B on its own.


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[Romasik]

Thanks, mono!

Still, can't get it. We already have running engine generator, which is not weaker than APU generator. APU generator is able to hold all load, but engine generator - not? BTW, it says that any generator is capable to supply all aircraft demand. Why shed? And zero notification (except purser's tirade).
No single remark in the procedure. Is it designed to be this way?
It's not always possible to start both engines at the gate...

[Romasik]

Airbus also recommend that both A & B EXT PWR are connected when APU not available. Never B on its own.

There is no problem when A or/and B connected. It's all about disconnecting them:sad:

[TURIN]

The recommendation is to avoid overloading one 'side' of the bus power. In certain scenarios too much power can be drawn through only one EXT PWR. A is the recommended option if only one is available.


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[DutchOne]

Still, can't get it. We already have running engine generator, which is not weaker than APU generator. APU generator is able to hold all load, but engine generator - not? BTW, it says that any generator is capable to supply all aircraft demand. Why shed? And zero notification (except purser's tirade).

Is there anything wrong with the aircrafts NO BREAK POWER TRANSFER? Otherwise it shouldn't happen.

[Romasik]

Is there anything wrong with the aircrafts NO BREAK POWER TRANSFER? Otherwise it shouldn't happen.
May be... I'd like to know for sure before writing it in the log book...

[windowshopper2010]

Are you referring to your DDG?
Our MEL specifically advises to keep IFE OFF until both engines started.

[TURIN]

So, you go on a public forum with the fault, but won't write it up in the log. Why? Surely, the best people to ask are the people maintaining your aircraft.


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[bvcu]

Not a fault , use two ground power plugs and works fine. Look at the logic table for sequence depending on which power is supplying !

[SloppyJoe]

Why write up something that is not a fault. Look in the FCOM at the table where it details when NBPT is available. I assume your company is new to get the 330 or both yourself and the other pilot are new on type. Surprisingly this is not detailed in our FCOM3 but it is standard practice where I work to let the cabin crew know not to start the video until we start our taxi otherwise they will have to do a manual brief to the pax.

[Romasik]

Are you referring to your DDG?
Our MEL specifically advises to keep IFE OFF until both engines started.
The only MEL is APU. And there is nothing in that MEL about IFE... At least in our company MEL.
the best people to ask are the people maintaining your aircraft.
I wish...
it is standard practice where I work to let the cabin crew know not to start the video until we start our taxi otherwise they will have to do a manual brief to the pax.
That's already something. At least I know it's not a fault. We found it out after some time, but still were not sure this was the normal thing. It's really not clear from these wonderful Airbus books.
Not a fault , use two ground power plugs and works fine. Look at the logic table for sequence depending on which power is supplying !
It doesn't matter how many cables are plugged in. You still have to unplug them before pushback and back to square one: 1 engine generator supplying everything..

[spannersatcx]

NBPT Inhibition
The NBPT function is inhibited if the system detects that an electrical transfer with nonsynchronized
power sources may occur. This behaviour is aimed at protecting the electrical network
and can originate from an incorrect status of the contactor string or by one of the following actions.
1. For aircraft fitted with the classic EPGS
 Action on the "BUS TIE" cockpit pushbutton switch.
 APU auto-shutdown or manual shutdown by means of one of the manual emergency shutdown switches (APU FIRE PUSH on overhead panel, APU SHUT OFF at the nose landing gear, APU EMERG SHUT DOWN on refuel/defuel panel at the belly fairing).
If one of the above actions is performed, the GPCU generates the BITE message "GPCU CTRSTGS/PB BUSTIE (13XE)/APU AUTOSHUTDN" and inhibits subsequent NBPT operations. In the event these actions have not been performed and this BITE message is generated, TSM 24-00-00 must be applied.
Reset of the GPCU if the NBPT is inhibited To restore NBPT operation after it has been inhibited, a GPCU cold start is necessary in order to reset the software protection lockout associated with NBPT operation. Two reset
procedures, which consist in removing the power supply from the GPCU, are given in TSM 24-00-00 and are summarized here below:
 Remove all AC and DC powers from the aircraft (Batteries, EPA, EPB, APU GEN and
IDGs).
Or:
 Aircraft electrical network being supplied with only the APU GEN or with one or more
IDG:
a) Disconnect EPA and EPB.
b) Reset for at least 5 seconds GPCU circuit breaker 13XG.
2. For aircraft fitted with the EEPGS
 The NBPT function is not available when the BUS TIE push button switch is released,
however it is recovered when the switch is set back to the normal position. No BITE
message generated and no GAPCU cold start necessary to recover the NBPT function.

 The NBPT is not available during the electrical transfer which follows an APU autoshutdown
or a manual shutdown by means of one of the manual emergency shutdown
switches (APU FIRE PUSH on overhead panel, APU SHUT OFF at the nose landing gear,
APU EMERG SHUT DOWN on refuel/defuel panel at the belly fairing). The BITE
Message "49-61-00 APU AUTO S/D /APU MAST SW (14KD)/ GAPCU (40XG)" will be
recorded in the Ground Report. However the function will be available during subsequent
electrical transfers without requiring a GAPCU cold start.
C. The procedures and actions where the NBPT is inoperative:
1. Some actions might be used during aircraft operation and maintenance whereby, per design, the NBPT function is not operative:
 Simultaneous connection or disconnection of two electrical sources (Ex: simultaneous starts or stops of two engines).
 Disconnection of EPA or EPB by switching OFF the ground power unit, whereas the associated cockpit push button switch is let in "ON" position.

Although remote, the following conditions may render difficult the synchronization within the required time window:
 Transfers with a ground power unit providing fluctuating electrical parameters (Ref SIL 24-057).
 Transfers while there is a change in the electrical load demand leading to voltage fluctuations.
(e.g Flight controls actuation during the transfer, cargo door opening …)
 An IDG with highly worn pistons & block bores might have some difficulties to synchronize with an other power source while still fully able to provide correct power supply to the
aircraft.
D. Energization sequences using transfers where the NBPT is not
operative
In service experience has shown that the following energization sequences can be used during aircraft operation whereas they are not covered by FCOM Standard Operating Procedures.
 APU not available
As a general rule, at departure, when the APU is not available the NBPT is operative provided all IDG's are connected on the network before external power disconnection. If airport regulations do not allow starting all engines at the gate then the following sequences apply where some transfers are performed without NBPT.
 One IDG not available:
Whatever the sequence, a Break power transfer occurs at APU disconnection only. This does not happen on A330 due to MMEL condition that requires to keep the APU running with one IDG inoperative.

As TURIN says, write it up so that it can be looked at.

[Romasik]

Spannersatсх:

So, two engines before EXT POWER disconnection. Or else there will be no NBPT..
I'll read it again tomorrow... BTW, is it a maintenance document?

Thanks :ok:

[T.R Haychemu]

Are you selecting Ext A off on the p/b switch? (So AVAIL shows, rather than ON)?

Or are you just telling the ground staff on the headset they are clear to disconnect the GPU when you see the engine is started and the generator is online?

[safelife]

Have the guys with the GPU cart maintain connected and chase you during push pack ;)

Honestly I think there is no solution other than starting both engines at the gate, or live with no IFE until after second engine start.
The trick is just to see that coming and brief the cabin crew!

[Romasik]

Are you selecting Ext A off on the p/b switch? (So AVAIL shows, rather than ON)?
Or are you just telling the ground staff on the headset they are clear to disconnect the GPU when you see the engine is started and the generator is online?

It happens. Either pilots miss it or ground mechanic pulls the cable without command. But, of course, normally we disconnect with prior switching of. The same result on IFE...

Honestly I think there is no solution other than starting both engines at the gate, or live with no IFE until after second engine start.
The trick is just to see that coming and brief the cabin crew!

Looks like the only solution so far...

[SloppyJoe]

Spannersatcx

Looking at 1.24.10 P9 the table for NBPT there should be no NBPT using external power during the start with the APU INOP as the original poster is saying. This is not a fault but causes the IFE to reset if it is in use. Were you work everyone briefs the ISM not to start till after 2nd engine start and it is never written up when NBPT does not occur, should we be writing this up?

[DutchOne]

Looking at 1.24.10 P9 the table for NBPT there should be no NBPT using external power during the start with the APU INOP as the original poster is saying

Are you sure? According to my FCOM there should be NBPT between EXT and IDG(=ENG GEN).

[spannersatcx]

With the APU inop, NBPT will operate normally when,
EXT A is connected, IDG 1 is connected.
There will be a break when EXT A is disconnected and IDG 2 is disconnected.
So if you start both engines NBPT will operate normally.

It's been a long time since we've had a 330 with an inop APU so haven't experienced it lately. However the other day the capt said disconnect EXT power, before the APU GEN was fully on line and there was a break!

One of the operators we handle has IFE on from PAX boarding until doors open the other end, on transfer from EXT to APU power NBPT ops normal and there is no rebooting of the IFE and no reports of problems on engine start.

If in doubt write it up, we are here for a reason, and yes it is a maintenance document.

Have done the occasional reset of the GAPCU, but not very oftem the system seems to work well a majority of the time.

Hope that helps

[Romasik]

spannersatcx:

By the second page things start looking clearer:ok:

[SloppyJoe]

Are you sure? According to my FCOM there should be NBPT between EXT and IDG(=ENG GEN)

Yes I am sure, although I have just been out into town and someone must have broken into my house whilst I was away and switched that page in my FCOM with one similar to what you have in yours. :O

[DutchOne]

Hey SloppyJoe,

That's good. I think it was swapped for a reason. You might want to read that page. You will realise that you can learn something new every day:)

Good luck and enjoy