A320 Startup
 

2 Quick questions:

For A320 startup do you need:

1) Packs?
2) Fuel pumps?


Cheers


1234

Packs: No. Start valves are not supplied by the packs.

Fuel Pumps: SOP requires Fuel pumps to be on. I've started a B727 with them off (by mistake), but there is no reason to find out if this is possible.

I would recommend the fuel pumps on - saying that the gravity feeding system might be able to handle it.......


As for the packs the computer deals with the air supply, so you can have them on (not working), or off doing nothing (i think).

B

The engins will start.., you will receive a low pressure ECAM though

I'm sure I've seen some start with PACK 1 on and 2 off. Can you start with BOTH packs off though?

mmm...


1234

yes... as long as the bleeds are not. Remember, its the APU bleed starting the engines, even when one is started.

Don't get confused. If you are sitting ready for start with APU bleed on and both packs on (as you normally would) when you select eng mode selector to START, both packs turn off automatically.

Would the start also be possible with APU on but the APU BLEED button switched off? Would it engage automatically?

No. The start valve will open but with no pressure, nothing will start turning. If the start master is left on, after a time (depending on engine type) an ECAM warning will appear.

Fuel pumps
 

Interestingly if you start the V2500 with the fuel pumps off you don't get the low pressure warning until the secon engine start.

Not sure why. Perhaps someone could enlighten me?

Perhaps the alert is inhibited until after the second engine start because fuel pressure drops below a certain threshold (in regards to gravity feeding) which may coincide with centre fuel tanks unable to run after 2 minutes from engine start, hence no pressure triggering the master caution..

You can use the air conditioning in ground operations with the APU bleed, the switches are always in ON positon. The air conditioning packs will automatically turn off in the moment you select IGN/START in the engine mode selector. It turns on again about 20 seconds after the second engine is on.
The engines can be started with gravity feeding, you will have the abnormal procedure ENG/fuel pump lo press 1+2 for both engines in the ECAM.

The APU or external pnuematic cart supply the PACKS on ground. The PACKS have nothing to do with engine start but rather are only used for air conditioning on ground/air, and cabin pressurisation (controlled ofcourse by the CPC's). During engine start, as correctly pointed out in previous posts, PACKS automatically close once ENG MODE selector is at IGN/START, and open automatically 30 seconds after the second engine's N2 reaches 50% (on V2527 IAE engines).

The fuel pumps however need to be on for engine start as you would get the associated FUEL PUMP 1+2 LO PRESS ECAM.

Cheers

Well, once started with fuel pumps off.
After start the ECAM told us to switch'em on.
Easy. I love France.