MD-11 Flight Crew Operations Manual
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Air -
Description and Operation
Air.10.8
Cabin altitude remains at departure field elevation until passing through 5,000 feet
above departure field elevation.
With FMS data, the CPC schedule is enhanced when cabin rates are set as a
function of planned and predicted flight altitudes.
In automatic control, the CPCs:
• Prepressurize to about 100 feet below takeoff field elevation when slats
are extended.
• Climb the cabin during aircraft climbout according to takeoff altitude and
aircraft altitude.
• Schedule cabin to be at 8.6 psi, or less, higher pressure than ambient
during cruise. This limits cabin altitude to 8,000 feet.
• Descend cabin during aircraft descent according to landing elevation and
aircraft altitude or, if FMS data is available, the planned flight altitude
schedule.
The CPC FAULT alert indicates one of the two CPCs has failed and control has
been switched to the backup CPC.
If the second CPC fails, the system switches to manual mode. The SEL CAB
PRESS MAN alert is displayed and the CABIN PRESS SYSTEM SELECT light
illuminates.
In manual mode, the flight crew can adjust the outflow valve position with a
CABIN PRESS rate selector on the CABIN PRESS control panel.
Automatic Operation
Normal Configuration
During normal configuration operation, the ESC pressurizes the 3 pneumatic
systems, operates the 3 packs, reconfigures the pneumatic system for engine start,
and monitors for the following failures:
• Manifold failures.
• High manifold temperatures.
• Low anti-ice pneumatic supply.
• Avionics and CAC fan failures.
• Cabin pressure failures.
• Trim air failures.
• Pack failures.
• Anti-ice failures.
• Recirculation fan failures (Passenger Configuration).
Phase of Flight Configuration
The ESC senses phase of flight and operates the systems as required. The phases
of flight and the associated functions are:
October 02, 2006
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