737NG APU in Main Engine Start (MES) mode [Archive]

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allendc

18th Apr 2006, 14:36

Hello
I have a quick question about the 737NG APU in Main Engine Start (MES) mode. In main engine start mode, the APU ECU opens the APU Inlet guide vanes to meet the increased airflow requirements.

Anyone have the specification on the increase in APU bleed pressure during MES mode?

Thanks in advanced.

David
www.737FlightSim.com

DDG

21st Apr 2006, 05:18

AlliedSignal 131-9b APU as fitted to the B737NG has a bleed load operating limit at sea level,60F day of 160pounds per minute at 60psi.The ECU will modify this output pressure and flow during MES mode depending on actual atmospheric conditions to allow for changes in surge margins.
Best info i could find at hand,referance was AMM part 1 Chapter 49-00-00 page 5.
Cheers