Originally Posted by
wheremi
Why pack1(2) overheat when its closed. For example pack1 on,pack2 off, apu bleed on. In this configuration pack2 will overheat in 10-15 minuets. Why it is so ?
The packs are located in a very tight compartment in the belly. The APU duct also runs through there
When pack 1 runs, it generates a lot of heat in the ambient area. The opposite pack when switched off, doesn't have any cold air exiting it's own turbine so it simply soaks up the heat from the surrounding area and triggers an overheat message.