How much unusable fuel is in the A320?

Question

I was wondering how much unusable fuel is in each tank or maybe in total for an A320. I searched through the FCOM and could not find answers.

To add to this question is the fuel shown on the fuel SD page all usable fuel? Or is it unusable + usable fuel?

Please show the references to the answers.

Answer 1

You can find the amount of unusable fuel in the EASA Type Certificate Data Sheet. Here is an example table for the A320-200 from that document:

In general, the cockpit displays will always show the amount of usable fuel only. This is mandated e.g. by EASA CS 25.1337:

(b) Fuel quantity indicator. There must be means to indicate to the flight-crew members, the quantity, in litres, (gallons), or equivalent units, of usable fuel in each tank during flight. In addition –

1. Each fuel quantity indicator must be calibrated to read ‘zero’ during level flight when the quantity of fuel remaining in the tank is equal to the unusable fuel supply determined under CS 25.959;
2. Tanks with interconnected outlets and airspaces may be treated as one tank and need not have separate indicators; and
3. Each exposed sight gauge, used as a fuel quantity indicator, must be protected against damage.

^{(EASA Easy Access Rules for Large Aeroplanes)}