PNEUMATICS
AIR CONDITIONING
AND PRESSURIZATION
AIRPLANE
OPERATIONS
MANUAL
2-14-05
Page
6
Code
01
DECEMBER 20, 2002
PNEUMATIC SYSTEM FUNCTIONAL LOGIC
The pneumatic system functional logic provides automatic control and
protection for itself and the user systems, giving priority according to
the airplane operation or condition.
ENGINE BLEED VALVE LOGIC
The Engine Bleed Valve (EBV) opens when the following conditions
occur simultaneously:
− Bleed Air Button is pressed to open the valve;
− Respective Essential Bus is energized;
− There is no massive leakage on the respective side of the rear
electronic compartment;
− There is no leakage downstream of the respective pre-cooler;
− Respective engine N2 is above 56.4%; and
− Respective engine fire extinguishing handle is not pulled.
− Bleed is requested by one of the bleed consuming systems
(airplanes Post-Mod. SB 145-36-0028).
APU BLEED VALVE OPERATIONAL LOGIC
The APU Bleed Valve (ABV) receives an electrical input to open when
the following conditions occur simultaneously:
− APU Bleed Button is pressed to open the valve;
− Essential DC Bus 1 is energized;
− Engine 1 bleed valve is closed (no pressure from the left side);
− Engine 2 bleed valve or cross-bleed valve is closed (no pressure
from the right side);
− APU rpm above 95% after 7 seconds; and
− There is no massive leakage on the APU line.
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