I have a question relating to APU fuel system. As said in material, there are 2 system supplying fuel for APU to operate. 1st one is primary and 2nd one is secondary.
In the 1st system or low pressure system, there is an APU fuel boost pump locating in LH main fuel tank. Its said that this boost pump is used in starting process or in condition when fuel feed system is lower than required.
Does it mean that, in normal condition, APU fuel boost pump is OFF and fuel is supplied to APU by Main Engine Boost Pump (or Engine Driven Pump)?