A320 DC bus fault and Cabin Pressure question

[nj314]

Hi, my question is:

Dc bus 2 fault ==> Cab press 2 fault, Ecam says “descend FL100 or MEA”

while Dc bus1+2 fault ==> lost cab press 1+2, Ecam does not tell you to descend?

Thanks

[FlightDetent]

Hello nj314. Please re-phrase, or maybe the aircraft have different elec configurations (could be, ours are quite aged)? Because what I see in the FCOM is different from your question:

FCOM PRO-ABN-CAB_PR "H": CAB PR SYS 2 FAULT
Crew awareness.

There is no mention to DES FL100/MEA, as the second remaing system takes over in full, without any degradation of capability.

PRO-ABN-CAB_PR "I": CAB PR SYS 1+2 FAULT
MODE SEL................................. MAN
MAN V/S CTL....................... AS RQRD

There is no mention to DES FL100/MEA, as the ECAM directs us to manual control of the outflow valve, which enables to keep the pressure under control and within limits.

Moreover, SYS 1 seems to be powered by DC ESS bus,
Výst?ižek.PNG
Thus should be not affected by loss of DC1 and DC2 busses. The other three DC buses should remain operative, and in consequence PR SYS 1 too.

BTW: does anyone know what is the meaning of the three letter codes next to individual busbars in this FCOM schematics? Thanks in advance.
bNgd.png

[Meikleour]

Doesn't the code not refer to the cb location on the flight deck?

[vilas]

For DC bus2 fault there are certain MSN numbers that has ECAM stating if Abnormal cabin pressure Max FL 100. While others don't say that.

[vilas]

DC BUS2 fault
MSN 0400, 0976-1010 doesn't have the restriction

If ABN CAB V/S:
MAX FL................ 100/MEA

[nj314]

thanks for your inputs