Boeing 747`s - PACKS

[Guest]

Hi,Can any expert let me know exactly what the `PACKS` are for on the747. When are they used, when turned on etc.Thanks for any replyJohn

[Peter Clark 21]

The packs (simplified) are part of the HVAC system of the aircraft, as well as providing controlled airflow for pressurization. For the 74x generally at least 1 is turned on when the crew arrives for the pre-flight, all but one are turned off when starting engines, all are turned on during taxi (unless you need extra duct pressure for anti-ice, but all are turned on after liftoff regardless because they do the pressurization and you need them for climb), and all but 1 are turned off after parking at the destination (so you keep the cabin comfortable for disembarking the passengers).Course, this is highly simplified...Take care!P

[Guest groundpounder75]

Check out wwww.aerowinx.com for a good tutorial on packs.