Pilot's Operating Handbook
Section 7
Description
Edition 0 - October 31, 2013
Rev. 6
Page 7.9.3
System operation
See figure 7.9.3.
The BLEED switch allows selection of the engine bleed air system provided that the
engine is running.
The Ground Fan (GF) operates until takeoff, when BLEED switch is set to AUTO, and
MAIN GEN is OFF.
The BLEED switch is fitted with a blocking device between AUTO and OFF/RST
positions. This prevents the operator from inadvertently setting the BLEED switch to
OFF/RST position.
To reset the system, set BLEED switch to OFF/RST, then back to AUTO.
System protection
Power for the engine bleed air system is supplied by the BUS 2 bar and is protected by
the CAB BLEED breaker.
Cabin pressurization control system
In flight, the GASC controls the modulation of the Outflow Valve (OFV) in order to
reach the computed cabin altitude.
System operation
See figure 7.9.3.
The BLEED switch allows to activate the pressurization system.
The PRES MODE switch allows selection of either one of two pressurization modes :
- If set to AUTO, the GASC controls the cabin altitude rate of change in order to :
. optimize comfort,
. avoid reaching maximum or negative cabin differential pressure.
- MAX DIFF mode controls the cabin pressure to assist passengers that might
require the lowest cabin altitude possible. When selecting this mode :
. flights below 13500 ft will result in cabin altitudes as low as 0 ft,
. for flights above 13500 ft, the cabin altitude is minimized throughout the
flight while maintaining cabin differential pressure below 6.0 PSI.
The GASC controls the OFV through a torque motor on the valve.
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