EICAS ECS synoptic

[John H Watson]

Would you get a flow bar if you used EXT AIR to operate Wing Anti-Ice? (and nothing else) i.e. if you put the aircraft in air mode.

Rgds
JHW

[John H Watson]

Another related question:

Would you get the EXT AIR annunciation if no packs were turned on and both Wing Isolation Valves were closed?

Thanks
JHW

[delcom]

Is a green flow bar removed if the respective pressure is below 11 psi? E.g. a flow bar to an AI or a pack, is this bar removed if the pressure at the AI or pack is below 11 psi?


|-|

Hard to say, since we do not normally decrease pressure or completely shut air on already running packs. However if the green flow line logic on the ECS page is generated the same way as for the HYD page...I'd say yes, green flow line(s) is/are removed below 11 psi.

Example 1: external air feeding air to say PACK 1, and I slowly close the cart valve. All logic components agree to draw the green flow line, except the pressure transmitter when it drops below 11 psi.

Example 2: whatever source is feeding air to PACK 1, and there is a serious leakage, the source is not capable of keeping the left wing pneumatic manifold above 11 psi.  

greetings,
delcom

[delcom]

Another related question:

Would you get the EXT AIR annunciation if no packs were turned on and both Wing Isolation Valves were closed?

Thanks
JHW

No, this big momma has no idea whether or not external air is on or not in this scenario. So no, you'd get no EXT AIR annunciation.

Since the crossover manifold is not equipped with a pressure transmitter, it's impossible to determine from the flight deck whether external air is connected or not. Yes, of course you can open one isolation valve or turn on PACK 2 in order to find out, but then wait for your scared/angry colleges to come upstairs and kick you in the #%*.      

d

[John H Watson]

Thanks, Delcom.

I'm not 100% convinced, however, that the ECS synoptic needs bleed duct pressure values. Normally, pressure indication circuits are not used for logic purposes (this is usually done by pressure switches on Boeings)

I might try a few experiments to see what happens in the following circumstances (with no bleed air on the aircraft):

1) WAI CMC Ground Test (looking at the synoptic) with isolation valves open
2) Both Isolation Valves closed and #2 pack valve cannon plug removed (removing the plug fools the aircraft into thinking the pack valve is open)


A flow bar is generated when you feed the #2 pack with the APU with both Isolation Valves closed, so there doesn't seen to be any requirements for duct pressure sensors in this situation.

3) With bleed air on the aircraft (APU) feeding a pack, shut off the bleed air. The pack valves open at 12psi, according to the manuals, but I suspect there may be some hysteresis on shutdown. The duct pressure might read below 11/12 psi before the pack valve actually closes. If the green flow bar disappears at a low psi, then I suspect the synoptic is not using duct pressure.

I'm working in a Line environment, so I might get opportunities to do things that you might not be able to do (and vice versa), without getting my *^$% kicked

Rgds
JHW.