MFC, the MultiFunction Computer

This is the heart of the ATR72. If it is not powered, almost nothing can be switched on. Should the ATR72 loses it's batteries (drained flat), you would not be able to charge the batteries through a GPU (Ground Power Unit). Why? You still need the MFC to authorise the switch.
No batteries = no MFC.
No MFC = no switches are authorised.

That's the beauty and bane of the MFC. It makes life so much easier, if it is powered.

General description

There are two independent computers (MFC1 and MFC2). Each is with two independent modules (A and B). So there are four modules 1A, 1B, 2A, and 2B. The MFCs monitors, controls and authorises the aircraft systems. It manages system failures (auto switching to backup), monitors system limits and thus triggers warnings. Most function are duplicated, so a failure on one module will still allow systems to function but at a degraded state (Example, visual warning but without aural chime).
When the aircraft is powered (Battery ON), all the modules goes into self test.
There is an exception though. With the aircraft not powered, when the cargo door panel is opened, the MFC 1A and 2A goes into self test. So when the aircraft is subsequently powered, only 1B and 2B goes into self test, since 1A and 2A was already tested.

Should the MFC faults, always try a reset. That fixes it almost every time.
The ATR72 can be dispatched with one module inoperative.