Questions about the bleed air system

Hi Two things I’m curious about. First, the documentation
seems to suggest that APU BLEED PRESSURE RECEIVED BY ENGINE only considers
bleed air coming from the APU. However, during experimentation in the A320neo,
I found that it also considers engine bleed as it matches the TURB ENG BLEED AIR:1 and TURB ENG BLEED AIR:2 exactly, even with APU bleed turned off.

Secondly, looking at the same
screenshot above. I am wondering whether it’s intended for both engines to
provide bleed air to each other (according to APU BLEED PRESSURE RECEIVED BY ENGINE) even when BLEED AIR ENGINE:1 and BLEED AIR ENGINE:2 are off? I
believe the reason for this behavior to be that BLEED AIR SOURCE CONTROL is
3, meaning the engines can provide bleed air. This is the case because
BLEED AIR ENGINE:3 is set to on, so the system sees at least one engine
providing bleed air, even if the A320neo only has two engines. I find this
confusing because spawning on the runway shows all BLEED AIR ENGINE:i to be
on. Consequently, even turning off both BLEED AIR ENGINE:1 and BLEED AIR ENGINE:2 will leave bleeds 3-99 (?) supplying bleed air, which is not
correct. It also means that it’s possible to perform a crossbleed start on the
A320neo with both bleed air pushbuttons off. Alternatively, is there a way to
have only BLEED AIR ENGINE:1 and BLEED AIR ENGINE:2 on during
initialization? It doesn’t make much sense to have the others on when the
aircraft has only two engines? At the moment, it seems like the way to do it
would be by invoking the ENGINE_BLEED_AIR_SOURCE_TOGGLE event to force all
engine bleeds off, then manually turning them on for #1 and #2. Is there an
easier way through a .cfg or .flt file? Thanks for looking into this :slight_smile: