APU start on batteries

[PS74 3]

Good evening,

just a quick question, is it possible in the MD to start the APU without additional GPU. I mean, Batterie master on, proper fuel pumps setting and APU master start. I tried it several times, APU starts, EGT and N rotation starting and than a shut down of the APU after prox 20 percent N rotation.

Maybe in the real plane not possible, but specially on isolated airfields it should be working. May I do someting wrong?

greetings

Peter

[Wothan 173]

You must turn on the Start pump situated on the left side of the overhead panel somewhere below the Galley power switch.

[PS74 3]

Ah okay, thank your. I thought the start pump is only related for engine start!

will try it later!

greetings

peter

[PS74 3]

with start pump on APU start on batteries was good! thanks for the advise.

Peter

[FormerSF3 15]

This is due to the main fuel pumps are on the AC BUS.  The START PUMP is a DC motor that can be used off the battery.