View Full Version : A320 DC EMER CONFIG
Simple question, understand the whole procedure apart from the following note :-
"DC ESS BUS is lost at landing gear extension" in expanded sts explanation in fcom. This is on a new aircraft with the lower rat stalling speed. Cheers for any insight.....
nj314
14th Jul 2017, 06:53
this is not in the fcom but I googled it.
This is due to the position and/or design of the RAT which supplies the DC ESS. On old models, the RAT stops working at 140kts (app speed when gear down). On new models, RAT are made to stall only at 100kts (after landing, when decelerating), so it does not relate to gear extension aynymore.
These are my two cent...
vilas
14th Jul 2017, 10:18
This is for old aircrafts where RAT used to stall with gear extension. Newer MSNs do not have this condition.
PENKO
14th Jul 2017, 13:55
Our newest 2017 neo has this condition as well so I doubt it's to do with the RAT stalling.. Even worse, you loose all comms.
Goldenrivett
14th Jul 2017, 16:06
Hi MBR,
Old FCOM 1.24.10 P 13.
"The emergency generator supplies the AC ESS BUS and the DC ESS BUS, via the ESS TR.
When the landing gear is down, the emergency generator is no longer powered, and the emergency generation network is automatically transferred to the batteries and static inverter, and the system automatically sheds the AC SHED ESS and DC SHED ESS buses."
When the gear is down (NOSE L/G UP / DOWN logic) then the emergency generator is isolated from AC ESS and ESS TR.
Your DC EMER CONFIG was because you had lost DC1, DC2 and DC ESS busbars - thus no more DC ESS.
See this link to Old RAT.pdf (http://www.blackholes.org.uk/PP/RAT1.pdf)
The new RATs have a lower stalling speed and the logic is to keep the Emergency generator coupled until the RAT stalls or if on ground and GS<100 kts. The nose gear logic has been removed.
On new aircraft, I suspect the warning about loosing DC ESS with gear down is in error.
http://www.blackholes.org.uk/PP/Rat new.png
Thanks for the replys. I understand the older RAT's but even then did it not just ditch the AC/DC SHED ESS when the RAT stalled ?
Anyway, newer MSN number and the warning is in the fcom along with the point @PENKO points out that with it goes the comms as well.
Point is that the SHED buses do get SHED at certain points but this clearly states the DC ESS BUS is lost at gear extension.
If you check the distribution table for DC ESS BUS there is not one configuration where you lose power to it.
The most demanding situations - 8s when the RAT couples, RAT stalls or on the ground at reducing speed BAT 2 supplies DC ess.
So why is this in there? A hang up from the old days? not even sure that is right - with the RAT stalling on the older MSN numbers I thought you lost the SHED buses only.
If anyone has the FCOM of an old MSN number (smaller RAT) if they could check if it was the AC/DC SHED bus that were lost when the gear was dropped that would be great! A print screen would be good for the older MSN........also if anything is written about the DC EMER CONFIG in the older MSN fcom.
Cheers
Goldenrivett
18th Jul 2017, 06:40
If anyone has the FCOM of an old MSN number (smaller RAT) if they could check if it was the AC/DC SHED bus that were lost when the gear was dropped that would be great! A print screen would be good for the older MSN........also if anything is written about the DC EMER CONFIG in the older MSN fcom.
Er.... That's what I posted.
tom775257
18th Jul 2017, 08:36
Anyone tried this in the sim recently? It would seem a big mistake to keep the note in error.
Mind you it wouldn't be the only way to lose all comms with elec problems. On some MSNs with a DC ESS bus failure, you lose all comms anyway due to AMU audio cards failure.
When the gear is down (NOSE L/G UP / DOWN logic) then the emergency generator is isolated from AC ESS and ESS TR.
Your DC EMER CONFIG was because you had lost DC1, DC2 and DC ESS busbars - thus no more DC ESS.
@Goldenrivett sorry mate, read it again I missed some details in your post. So the SHED's are lost on the old RAT thanks.
The point above though, why would you lose DC ESS surely even when you have lost the old RAT and the emerg gen the DC ESS is still powered directly from BAT 2?? It says it connects automatically on emerg gen loss. On the old rat that is.
@tom775257 yep, we still have a few of these as well! Nice little surprise ehh !!
It would be great to run the DC EMER CONFIG fault in the sim see what actually happens. As far as I can tell its not a hang up from the old rat system, but I'm not sure it would actually lose the DC ESS in real life ..
Goldenrivett
18th Jul 2017, 11:13
why would you lose DC ESS
Sorry, I must be really crap at trying to explain things.
The original electric problem was loss of DC1 and DC2 and DC ESSential bus bar which ecam reports as DC EMER CONFIG.
You managed to recover DC ESSential by connecting it to the EMER Generator via the ESS TR. Thus, when you loose the EMER Generator, then you are back to your original condition of No DC ESSential.
cheers, I take it you are talking about the old RAT here and the older MSN numbers? so starting with the older MSN numbers..... the RAT stalls yes, but did you used to lose the DC ESS in this condition? You used to use the DC ESS SHED yes, but I've not seen it written down that you actually lose the DC ESS BUS. Infact :-
Old FCOM 1.24.10 P 13.
"The emergency generator supplies the AC ESS BUS and the DC ESS BUS, via the ESS TR.
When the landing gear is down, the emergency generator is no longer powered, and the emergency generation network is automatically transferred to the batteries and static inverter, and the system automatically sheds the AC SHED ESS and DC SHED ESS buses."
The sentence above implies that the SHED's are lost but the AC ESS is powered via the static inverter from battery 1 and DC ESS is powered directly from BAT 2 which makes sense.
For the newer MSN numbers the original post of mine with ref to losing the DC ESS BUS at landing gear extension makes even less sense as the RAT does not stall.
I did think that maybe it was a hangup from the older design that had been left in there (but we seemed to have proved that even then we just lost the SHED buses and not actually the ESS BUSES of AC and DC)
I cant see much difference between the DC EMER CONFIG and the ELEC EMER CONFIG with regards to the configuration of the DC BUSES.
Disregarding AC1/AC2 loss in elec emer config and looking at the DC side of things you have still lost DC BUS 1/2 plus DC BAT BUS in both configurations, with the emerg gen supplying AC ESS and DC ESS.
However on the dropping of the gear in the EMER ELEC config there is no warning of loss of DC ESS BUS like there is in the DC EMER CONFIG........
vilas
18th Jul 2017, 17:44
MBR
It has to do with MSN numbers. I have produced three set of MSNs. Only the first set has DC ESS availability with gear up and with gear down all communication lost. It also suggests landing Conf before gear down.
Ident.:PRO-ABN-24-X-NG01112
Applicable to: MSN 0199-0240, 0264
Ident.:PRO-ABN-24-X-00012547.0002001 / 24 JUN 13
64
LAND ASAP (AMBER)
L2Triggered, if DC BUS 1, DC BUS 2 andDC ESS BUS are lost. In addition, DC BAT BUS is lost.
L1EMER ELECPWR..................................................... ............................................................ MANON
L2Landing flaps must beestablished before landing gear extension.
The emergency generator supplies DC ESS BUS, as longas the landing gear is up.
But, DC BUS 1, DC BUS 2, and DC BAT BUS are still notsupplied.
Note: DC ESS BUS is lost atlanding gear extension.
Consequently, all means ofcommunications are lost since all ACPs are lost.
Ident.:PRO-ABN-24-X-NG01112
Applicable to: MSN 0557
Ident.:PRO-ABN-24-X-00012547.0003001 / 05 MAR 13
66
LAND ASAP (AMBER)
L2Triggered, if DC BUS 1, DC BUS 2 andDC ESS BUS are lost. In addition, DC BAT BUS is lost.
L1EMER ELECPWR..................................................... ............................................................ MANON
L2The emergency generator suppliesDC ESS BUS.
But, DC BUS 1, DC BUS 2, and DC BAT BUS are still notsupplied.
Ident.:PRO-ABN-24-X-NG01112
Applicable to: MSN 0976-1818
Ident.:PRO-ABN-24-X-00012547.0003001 / 05 MAR 13
68
LAND ASAP (AMBER)
L2Triggered, if DC BUS 1, DC BUS 2 andDC ESS BUS are lost. In addition, DC BAT BUS is lost.
L1EMER ELECPWR..................................................... ............................................................ MANON
L2The emergency generator suppliesDC ESS BUS.
But, DCBUS 1, DC BUS 2, and DC BAT BUS are still not supplied
@Vilas. Thanks for the info.
The fcom I'm looking at still has the following warning for a much later msn number (3xxx)
Note:
DC ESS BUS is lost at landing gear extension.
Consequently, all means of communications are lost since all ACPs are lost.
To verify the list of STATUS INFO, Refer to .......
So I wonder if this has been left in there from previous, very early, msn numbers.
Fursty Ferret
19th Jul 2017, 09:34
It also suggests landing Conf before gear down.
You can't extend either flaps or slats with the loss of DC ESS and DC2, hence the "must".
I've looked at our FCOM and for the most antiquated aircraft in the fleet (MSN ~1000), this warning still applies. For all the others, it's been deleted.
To be honest, I don't think you can really get into the DC EMER CONFIG by itself. The "loss of DC ESS" at gear down is just as likely to be "loss of AC and DC ESS", meaning you're landing the aircraft on computers supplied by the HOT buses and standby instruments. All radios (nav and comm) are lost. But you get to keep the clock. ;-)
Cheers for all the input.
I guess it's see what you get on the very slim chance it happens. Just interesting that it's still written in there on the new msn numbers. At least I'm not missing anything which I thought I might be