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)?

  • $\begingroup$ Hi Harry. I edited the title of your question to try to summarize what you are asking. Feel free to Edit further. $\endgroup$
    – user
    Commented Feb 4, 2019 at 16:11
  • $\begingroup$ Thanks @a CVn :) $\endgroup$ Commented Feb 4, 2019 at 22:02

1 Answer 1


The LH fuel line feeds the APU unless the pressure is too low. In this case the advisory "FUEL LO PR" will be displayed on the APU page of the lower ECAM and backup pump is started.

From the A320 family FCOM:

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