PILOT’S OPERATING HANDBOOK
SECTION 7
DESCRIPTION
Edition 0 -- October 31, 2013
Rev. 1
Page 7.9.4
CABIN PRESSURIZATION CONTROL SYSTEM
The cabin altitude check is automatically ensured by the pressurization control system through a monitoring of the
cabin pressure. The opening of the Outflow Valve (OFV) is controlled by the GASC through a torque motor fitted on
the valve.
The Landing Field Elevation entered by the pilot in the MFD is used by the GASC to manage the optimal cabin
altitude rate of change in order to land with a cabin altitude equal to LFE minus 200 ft.
The Landing Field Elevation selection is done using :
-
Destination airport of the flight plan pressing ”SYSTEM” and then ”FMS LFE” on the MFD
-
A manual entry pressing ”SYSTEM” then ”MAN LFE” on the MFD.
The cabin altitude is automatically calculated by the GASC using the data sent by GDU 1500 MFD.
In flight, the GASC controls the opening of the OFV in order to reach the automatic computed cabin altitude. The
”PRES MODE” switch allows to select 2 pressurization modes :
-
if set to AUTO, the GASC controls the cabin altitude rate of change in order to optimize comfort and avoid
reaching maximum
∆
P or negative
∆
P
-
if set to MAX DIFF, the cabin altitude is minimized throughout the flight. For airplane altitudes below 13500 ft,
this results in cabin altitudes that could be as low as 0 ft. Above 13500 ft, the cabin altitude is minimized while
maintaining
∆
P
≤
6.0 PSI.
The GDU 1500 MFD shows landing field altitude, cabin climb speed in Sea Level ft/min and cabin-atmosphere
differential pressure (
∆
P) in PSI.
Cabin is automatically depressurized as soon as the airplane is on ground through landing gear switch (airplane on
ground) or, if necessary, by actuating ”DUMP” switch located on ”ECS” panel (in normal operation, this switch is
protected and locked by a cover).
Overpressure and negative relief safety are managed by both OFV and SFV. The safety functions are ensured by
independent pneumatic modules fitted on both valves, which override the GASC control when necessary.
The
”CABIN ALTITUDE”
CAS message appears in the GDU 1500 MFD ”CAS” window (in display normal
conditions) when the cabin altitude is over 10000 ft.
The
”CABIN DIFF PRESS”
CAS message appears in the GDU 1500 MFD ”CAS” window (in display normal
conditions) when the cabin-atmosphere differential pressure is over 6.2 psi (427 mb).
The ”DUMP” switch allows the pilot to open the OFV in order to de-pressurize the cabin. The OFV is fitted with a
cabin altitude limitation device which overrides the ”DUMP” function and forces the closure of the OFV if the cabin
altitude reaches 14500 ft.
The
”CPCS BACK UP MODE”
CAS message appears in the GDU 1500 MFD CAS window when, due to
malfunction, GASC cannot compute optimal cabin altitude.
In this case, cabin altitude is controlled by GASC to 9800 ft default value.
