Engine Interface Unit

[AF330]

A320 Engine Interface Unit (EIU)

Good morning,

Can anyone explain me what is the purpose of the EIU on the bus?
It is connected with the FADEC (ECU).

F-COM says that when we put the engine selector to START/IGN, it closes 1 PFCV (Pack flow control valve.).

But the engine selector is connected with the EIU. So basically (e.g), EIU sends a signal to the pack controller to close PFCV?

What else does it do?

Thanks in advance

[737Jock]

Have a look at what happens when the EIU fails.

[AF330]

Good evening,

Yes, that is really a very good idea!

Ok, so found this:



When we put the engine mode selector:


When the NORM position is selected, continuous ignition A and B is automatically selected when an engine is running and one of the following is met:

- FLX or TO/GA thrust is selected on the ground
- TO/GA thrust is selected in flight
- ENG ANTI ICE switch is ON
- Engine surge or stall occurs in flight
- FLAPS lever position is other than 0 in flight (approach idle is selected)

So we know that the selector is connected with the EIU but the thrust levers are connected with ECU (FADEC). So EIU has said to ECU to give continuous ignition A and B when levers are at FLX or TOGA on ground and at TOGA during flight.

We can see that the ENG ANTI ICE switch is connected with EIU.
So I think that EIU opens the engine anti-ice valve and tells the ECU to give continuous ignition.

When the selector is selected to START on ground, in an automatic starting sequence, the start sequence is identified:
- ECAM displays engine page
- Pack valve close (1)
So EIU will close 1 PFCV (pack flow control valve).

When the ENG MODE selector is positioned to IGN/START inflight the ENG MASTER switch is armed and provides continuous ignition using both igniters.
So EIU will ask ECU to do it.

When the ENG MODE selector is positioned to CRANK, the start valve opens if the ENG MAN START switch is ON and N2 is less than 10%. Ignition is not supplied. So the EIU will ask the ECU to open the starter valve.

Now, with the master switch:



Selecting ENG MASTER switch to ON:

- Opens the LP fuel valve if the ENG FIRE switch is IN
- Initiates an automatic start, if the ENG MAN START switch is OFF
- Initiates a manual start if the MAN START switch is ON

So EIU will ask ECU to open LP fuel valve. Will talk about the start later.

Am I right till here?