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Goldbird
5th May 2011, 12:25
Good afternoon

Wondering if anybody could help me with this, I need B752 APU fuel consumption for these 3 circumstances.

-Electrical (Ground)

-Electrical Load (FL350)

-Pneumatic Load

Source of information would be highly appreciated.

Regards

mustbeaboeing
6th May 2011, 22:19
This is about all I can find.



Ground Operations

Fuel can be saved by minimizing APU utilization.
Average APU fuel flow rate under normal operation is
105kg per hour on the ground.


APU Operation During Flight

For APU operation during flight, increase fuel flow
acording to the following table. These increments
include the APU fuel flow and the effect of increased
drag from the APU door.

Pressure
Altitude........ APU FUEL FLOW (KG/HR)
(1000ft)

39................ 70
35................ 75
31................ 85
25................ 95
20................ 105
15................ 110
10................ 125
5.................. 135


page 2.1.1

Source

Flight Planning and Performance Manual B757-200 RB 211-535
CAA July 30 2010



B757 Systems Manual states....

APU Electrical power is available throughout thre airplane operating envelope. In flight, APU bleed air is available up to approximately 17,000ft.



Hope this helps. A search on the web may find more.

Goldbird
7th May 2011, 11:57
Thank you for the comment, I have searched the web without any result, this table you mention is probably correct for Electrical load FL350 = 75kg,

I am guessing that the difference between Electrical(ground) and Pneumatic load is probably if we are using the APU bleed to feed the packs or not during ground operation

I have those figures for B737 classic APU

-Electrical (Ground) - 75kg/h

-Electrical Load (FL350) - 45-50kg/h

-Pneumatic Load - 115kg/h

According to these figures B737 APU under Pneumatic load has higher fuel flow than average B757 APU on ground.

Any more comments?