KLM MD-11 - Aft Cargo Compartment Heating and Ventilation System; Pressurization System

MD-11 Flight Crew Operations Manual
k
Air -
Description and Operation
Air.10.6
A thermostat controls temperature between 12.7° ±2.8° C and 18.3° ±2.8° C.
Aft Cargo Compartment Heating and Ventilation System
The aft cargo compartment is heated, ventilated, and cooled in flight. Pneumatic
system 2 bleed air heats the compartment. Temperature sensors maintain the
temperature, as selected by the flight crew. Animals may be carried in this
compartment.
The air vented into the compartment exhausts through two ceiling outlets, where
it is dumped near the cabin air outflow valve.
A flow detector in the flow stream of the exhaust ducting signals the flight crew
of insufficient exhaust airflow. Excess fan flow, over the exhaust flow, maintains
positive pressure in the compartment.
The Miscellaneous Systems Controller (MSC) automatically shuts off the
ventilation system if a compartment fire is detected. The flight crew manually
latches off airflow to the compartment. This prevents dilution of the firex agent,
and airflow does not resume when the smoke or fire signal ends. The firex agent
remains isolated inside the compartment when check valves close.
Pressurization System
The pressurization system controls the aircraft pressurization. Pressurized air
supplies the cockpit, cabin, cargo, center accessory and avionics compartments.
Pressurization is controlled by regulating the outflow of conditioned air from the
pressurized areas of the fuselage. Pressure relief valves limit the cabin differential
pressure to 9.1 psi. The CABIN PRES RELIEF alert is displayed when the relief
valves open up at a differential pressure of about 8.9 psi.
The Cabin Pressure Control System (CPCS) provides the following functions:
• Pressurization control during all flight phases.
• Fuselage overpressurization protection.
• Negative pressure relief provided by the door seals.
• Data for monitoring pressure levels and cabin altitude change rate.
Pressurization is normally controlled automatically. A manual back-up mode is
provided in case of failure of the automatic mode.
The CPCS allows flight up to 43,200 feet while maintaining a cabin pressure
equivalent to an altitude of less than 8,000 feet. The maximum cabin climb rate is
750 fpm and maximum cabin descent rate 350 fpm.
October 02, 2006