View Full Version : 737-800 APU Fuel Consuption
Mrs-rodge-bless-her
5th Jul 2010, 17:40
I cant seem to find how much fuel the apu uses per min.
Can anyone help?
Regards.
CaptainSandL
5th Jul 2010, 17:59
How long is a piece of string?
Try this link (http://www.b737.org.uk/apu.htm#Pack_Operation)for some figures in different configs.
As / big turbine engine performance it depends on environmental conditions / systems selections etc.
Select maint on FMC and APU (think these are the correct prompts) and it will give you the fuel flow for the specific condition you have at that point in time.
Nicoals
5th Jul 2010, 19:57
2 kgs a minute roughly
ampclamp
5th Jul 2010, 23:30
nicoals is about right.But it does vary widely depending on the load.use th APU bite via the CDU to see real time rate, temps etc.
egsshell
6th Jul 2010, 09:19
I am retired now, but I seem to recall that the MEL says to increase fuel consumption by 50 kg per hour if dispatched with APU running. This would typically be with APU bleed off and generator supplying the bus. The figure presumably takes into account the increased efficiency of the APU at altitude.
Not the 73 but similar size I imagine...
A320 = 130kg/hr on the ground
65kg/hr abv FL300 just to run it and becomes 80kg/hr if the gen is used at alt.
D O Guerrero
6th Jul 2010, 11:16
On a related note - anyone know why the APU burn is higher with one pack than it is with 2? I always thought it was because one pack in auto defaults to high if the other is off. Someone was telling me that is not the reason though - I didn't understand what he was getting at though - something about fans...
ampclamp
9th Jul 2010, 01:44
ng apu has a separate compressor for air unlike the classic that pulls air out of the engine.
so the engine needs to run the compressor anyway so unloading it by turning on bleed and the packs unloads the apu.
My terminology maybe dodgy but I think its close enough.
STBYRUD
9th Jul 2010, 07:07
The pressure demand of one pack running in high is higher than the demand for two packs running in normal configuration to deliver the same airflow - hence the APU has to work harder (the EEC cleverly adjusts VBVs and fuel flow) to deliver it.