Cargo Compartment Heating

ATA21

  • Hot bleed-air from the APU bleed-air duct goes through the pressure regulating valve 11HC and the trim-air valve 12HC. It then mixes with air from the cabin before going to the AFT cargo compartment. This air enters the supply duct upstream of the inlet isolation-valve 34HN.
  • Proximity switches are installed at the AFT cargo-compartment door and at the bulk cargo-compartment door. These switches will inhibit the AFT cargo-compartment heating system if one of the doors is open. Both doors must be closed to enable the heating system to function.
  • The temperature control system ( Aft Cargo Heating Controller 10HC ) regulates the amount of hot air added, to give the preselected temperature in the AFT cargo compartment. The heating controller 10HC, which gets information from the temperature sensors 13HC and 14HC, controls the system. These sensors are installed in the inlet duct (13HC) and at the extraction duct of the Cargo Compartment (14HC).
  • The temperature of the air, which enters the supply duct, is controlled to a maximum of 70 DEG.C (158.00 DEG.F) by the trim-air valve 12HC.When the duct temperature goes above 88 DEG.C (190.40 DEG.F), the FAULT light on the HOT AIR switch 16HC comes on and the pressure regulating-valve 11HC closes. This overheat condition is latched by the heating controller ( 10HC ). When the duct temperature decreases to 70 DEG.C (158.00 DEG.F) the system can be reset. To do this you must push the HOT AIR switch 16HC OFF and then ON again.
  • The temperature range that the selector can set is between 5 DEG.C (41.00 DEG.F) and 26 DEG.C (78.80 DEG.F) with 15.5 DEG.C (59.90 DEG.F) at the 12 o’clock position. However, if the temperature is, for example, already 15 DEG.C (59.00 DEG.F), the adjusting range lies between 15 DEG.C (59.00 DEG.F) and 26 DEG.C (78.80 DEG.F).
  • A hot trim-air valve 12HC is installed in the trim air supply duct to the AFT cargo compartment. The valve also has mechanical stops and limit switches. The limit switches stop the valve opening or closing more than their preset position and the mechanical stops are a backup. A manual override and a visual position-indicator are installed on the end of the shaft. The step counter of the controller 10HC counts the steps of the stepper motor to calculate the position of the valve butterfly for indication on ECAM. A return spring closes the trim-air valve 12HC if the power supply or the controller 10HC do not operate.
  • The pressure regulating valve (11HC) is used to control the pressure of the hot trim air supply to 4 psi above cabin pressure. The secondary function is to provide a shut-off facility to the aft cargo compartment. This butterfly type valve is under normal conditions actuated by a pneumatic actuator and controlled by a regulator. The valve is activated when the solenoid is energized.The valve can be operated manually and includes a visual position indicator. A limit switch indicates closed/not closed to the ACSC (47HH) and to the ECAM system.
  • The ventilation controller 10HN sends a signal to the heating controller 10HC to close the trim air valve 12HC if there is : a Fan Fault (35HN) or an ISOL valve closed (33HN, 34HN).
  • The AFT ISOL VALVE switch 36HN is installed on panel 22VU in the cockpit overhead panel. It controls the isolation valves 33HN, 34HN and the extraction fan 35HN. The cargo ventilation controller 10HN will only start the fan if a fully open signal is received from both isolation valves( 33HN & 34HN ). With the isolation valve switch 36HN pressed-in , the isolation valves 33HN and 34HN open fully and the extraction fan 35HN starts. With the isolation valve switch pressed-out, OFF light comes on white, the isolation valves close and the extraction fan stops. The FAULT light comes on amber if either isolation valve is not fully open or fully closed. If there is an isolation valve disagree (not fully open or not fully closed) the ventilation controller will also send a signal to the Flight Warning Computer (FWC).If there is an extraction fan fault, the ventilation controller gives a signal to the FWC via the ACSC1 47HH which generates the appropriate failure message for the Centralized Fault-Display System (CFDS) (Ref. 21-63-00 or 31-32-00).
  • Cargo compartment temperature :14HC
  • Duct inlet temperature :13HC
  • TASK 21-43-00-810-817-AAFT Cargo Temperature Sensor Fault

-AFT CARGO DUCT SENSOR (13HC).

-AFT CARGO COMP SENSOR (14HC).

Job need perform : Cleaning of the Cargo Compartment Duct Temperature Sensors and the Cargo Compartment-Temperature Sensor

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