in the engine shut down cl we see that if the eng 1 fire p/b is pushed we use apu bleed with xbleed at shut position.
We don't do it with engine 1 fire bush button pushed. But with No2 Fire button pushed you may do it if required. It's not mandatory.
‐ If the ENG 1 FIRE pb-sw is pushed, APU bleed must not be used.
If ENG 2 FIRE pb-sw is pushed, APU bleed may be used, provided the X BLEED
rotary selector is set at SHUT.