Originally Posted by
AerocatS2A
1. Airbus wants the APU bleed on prior to shutdown so it is available for a tailpipe fire and to avoid excessive pack cycles. The statement to do it immediately before shutdown to avoid fumes is in comparison to turning it on earlier. There is even less chance of getting fumes if you leave it until after shutdown down but this is not what Airbus recommend. They think it should be on, they recognise there may be fumes, to minimise the fumes they suggest putting it on as late as possible but still before engine shutdown.
Thank you I get what you are saying now.
If the APU Bleed is switched ON just before engine shut down , there will be some engine exhaust sucked in by the APU inlet but it will be minimum as compared to if you switch it on minutes earlier
Thank you