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tsrp
14th Nov 2007, 04:09
Why is there a Maximum Altitude limitation while the APU is running?


Thanks

tsrp

411A
14th Nov 2007, 04:42
On the L1011, it is an APU generator cooling issue.
Max KW reduced as well, while airbourne.

spannersatKL
14th Nov 2007, 06:45
APU Surge Margin and basicaly keeping the fire alight!

Chrome
14th Nov 2007, 12:14
There is no maximum altitude limitation running the APU on the A320 in a normal 2 engine operation. But at levels greater than FL300 or in greater ISA conditions, APU generator load reduces. There are however limits to APU battery-assisted starts and running the APU for bleed operation.

It has something to do with the pressure, density and temperature at higher levels. Someone else help, I am too hungry now to think :)