APU Feed

FWD APU pump runs when :

The APU is feed from the left inner tank, via the trim pipe. The APU feed has two pumps that operate mutually exclusive. The two APU fuel feed pumps are the FWD APU pump and the AFT APU pump.

The FWD APU pump has priority and normally feeds the APU. The Aft APU Pump functions when the FWD APU pump is not running.

On the ground (except for trim tank fueling)

In flight below FL255 except when FWD XFR occurs

In flight above FL255 when the Trim Tank is empty

AFT APU pump runs when :

On the ground when trim tank fueling occurs

In flight below than FL255 when FWD XFR occurs

In flight above FL255 unless Trim Tank is empty

When the APU feed is active, the APU low pressure valve is shown in green