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CARGO COMPARTMENT VENTILATION - DESCRIPTION AND OPERATIONThe AFT cargo-compartment ventilation-system, supplies air to the AFT cargocompartment. The ventilation air comes from the cabin zones through openingsin the cabin floor behind the sidewall panels.

System Description

AFT Cargo-Compartment Ventilation-SystemSuction from the extraction fan 35HN

causes air to flow into theventilation system of the AFT cargo compartment when the

extraction fan35HN operates on the ground or in flight. Three inlets installed along the

compartment lower left-hand sidewall, direct the air towards the compartment floor area.

An isolation valve 34HN is installed in distribution ducts upstream of the compartment

inlets.The AFT compartment air is extracted through two outlets near the compartment

ceiling on the aft end wall. The air goes through the extraction fan 35HN and an

isolation valve 33HN and is discharged in the area of the outflow valve 10HL.

B. System Performance

(1) Flowrate The flowrate through the AFT cargo compartment is:

Volumetric Airflow Mass Flow - ground 160 l/s 190 g/s,- flight 160 l/s 141 g/s.

Component DescriptionA. Cargo Ventilation ControllerThe cargo ventilation controller 10HN is of a modular construction and consists of: - achassis, - a common power supply module, - a FWD cargo ventilation module, - a FWDcargo power relay, - an AFT cargo ventilation module,- an AFT cargo power relay, - aspare module connector, - a spare power relay socket. These modules are enclosed ina metal case. They are installed on the outboard side of relay box103VU, in the avionicscompartment. The cargo ventilation controller 10HN controls and monitors the isolationvalves 33HN, 34HN and the extraction fan 35HN. The controller sends a signal toECAM and CFDS if there is a fault in the isolation valves or extraction fan.B. AFT Cargo-Compartment Isolation-Valves

The isolation valves 33HN and 34HN are electrically operated butterfly valves. Eachconsists of a body assembly and an actuator housing which are bolted together andinternally connected. The actuator housing contains a gear-train, two microswitches, a28 VDC motor and an electrical connector. The 28 VDC motor drives the gear-train,which turns a shaft to which the butterfly valve is attached. Two microswitchessignal the fully open/fully closed position of the isolation valves 33HN and 34HN to thecargo ventilation controller 10HN.Accidental blockage of either isolation valve will causea torque limit mechanism to disengage the gear-train. This protects the gear-train andbutterfly valve from damage. A manual override and visual position indicator isconnected to the end of the shaft at the top of the actuator.C. Extraction FanThe AFT cargo extraction fan 35HN is installed in line with the extraction duct. It ispowered by a three-phase four-pole induction motor that drives a fan-wheel. This fanruns continuously when the aircraft is on the ground or in flight. Thermo switches areinstalled inside the motor stators of the extraction fan. If the temperature of the stators

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CARGO COMPARTMENT VENTILATION - DESCRIPTION AND OPERATIONgets to 140 DEG.C. (254 DEG.F), the thermo switches isolate theelectrical supply to the fan. The AFT cargo extraction fan 35HN is secured with clampsto brackets on the aircraft structure in the rear underfloor area. Arrows on the fancasing show the direction of airflow through the fan and the direction that the fan-wheelrotates. If the impeller breaks up, the casing is strong enough to contain the debris.

These modules are enclosed in a metal case. They are installed on the outboard side ofrelay box 103VU, in the avionics compartment. The cargo ventilation controller 10HNcontrols and monitors the isolation valves 4HN, 5HN and the extraction fan 6HN. Thecontroller sends a signal to ECAM and CFDS via the Zone Controller if there is a fault inthe valves or fan. D. Pressure SwitchThe pressure switch 21HN consists of a body with two pressure ports, a diaphragm, a

spring, a microswitch and an electrical connector. One pressure port contains a filterand senses outside ambient pressure, the other senses cabin pressure. The diaphragm,when pressurized, exerts a force on a snap-action spring. When the differentialpressure gets to 1psi the spring will snap over and depress the microswitch actuator.

This sends a signal to the cargo ventilation controller 10HN which stops the extractionfan 6HN. When pressure decreases, the microswitch returns to its original position, thisremoves the pressure signal and the extraction fan startsA.OperationThe extraction fan of the ventilation system for the AFT cargo compartment operateswhen the aircraft is on ground and in flight.The cargo ventilation controller 10HN opensthe isolation valves 33HN and 34HN. After the ventilation controller receives fully opensignals from both valves, it starts the extraction fan 35HN.The controller will close theisolation valves, and stop the extraction fan when:- the isolation valve switch 36HN is selected OFF,- the smoke detection control unit 10WQ detects smoke in the AFT cargocompartment (Ref. 26-16-00).NOTE : In this case the isolation valves are closed/latched. Reopening is only possiblein the absence of a smoke signal by power interrupt.- the cargo SMOKE TEST switch 13WH located in the overhead panel (22VU) ispressed.NOTE : If the smoke test switch is pressed, the controller will receive the test signal andthe simulated smoke signal, the latter a few seconds later. In this case the isolationvalves are closed but not latched. Reopening happens, if the SMOKE-signal is removeda few seconds earlier than the Test-signal, which is controlled by the smoke detectionand control unit automatically.B. Control and IndicationThe AFT ISOL VALVE switch 36HN is installed on panel 22VU in the cockpit overheadpanel. It controls the isolation valves 33HN, 34HN and the extraction fan 35HN. Thecargo ventilation controller 10HN will only start the fan if a fully open signal is receivedfrom both isolation valves. With the isolation valve switch 36HN pressed-in, the isolationvalves 33HN and 34HN open fully and the extraction fan 35HN starts. With the isolationvalve switch pressed-out, OFF light comes on white, the isolation valves close and theextraction fan stops. The FAULT light comes on amber if either isolation valve is notfully open or fully closed.If there is an isolation valve disagree (not fully open or not fully

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CARGO COMPARTMENT VENTILATION - DESCRIPTION AND OPERATIONclosed) the ventilation controller will also send a signal to the FlightWarning Computer (FWC). If there is an extraction fan fault, the ventilation controllergives a signal to the FWC via the zone controller 8HK which generates the appropriatefailure message for the Centralized Fault-Display System(CFDS) (Ref. 21-63-00 or 31-32-00).

_CARGO COMPARTMENT HEATING - DESCRIPTION AND OPERATION1 . GeneralAft Cargo-Compartment Heating----Hot bleed-air, from the APU bleed-air duct, is mixedwith cabin-air and delivered to the AFT cargo-compartment ventilation-system (Ref.21-28-00). This raises the temperature in the compartment to a preselected level. Hotbleed-air from the APU bleed-air duct goes through the trim-air valve 12HC. It thenmixes with air from the cabin before going to the AFT cargo compartment. This airenters the supply duct upstream of the inlet isolation-valve 34HN. A proximity switch,installed at the AFT cargo-compartment door, inhibits the AFT cargo-compartment

heating system if the cargo-compartment door is open. This door must be closed toenable the heating system to function. The temperature control system regulates theamount of hot air added, to give the preselected temperature in the AFT cargocompartment. The heating controller 10HC, which gets information from thetemperature sensors 13HC and 14HC, controls the system. These sensors are installedin the inlet duct (13HC) and at the extraction duct of the Cargo Compartment (14HC).The temperature of the air, which enters the suppWhen the duct temperature goesabove 88 DEG.C (190.40 DEG.F), the FAULTlight on the HOT AIR switch 16HC comes on and the pressure regulating-valve11HC closes. This overheat condition is latched by the heating controller.When the duct temperature decreases to 70 DEG.C (158.00 DEG.F) the systemcan be reset. To do this you must push the HOT AIR switch 16HC two times.R **ON A/C 004-099,

A. Rly duct, is controlled to a maximum of 70 DEG.C (158.00 DEG.F) by the trim-airvalve 12HC.

B.