Trim-Air Valve Figure 006
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Temperature Controller - Location Figure 007
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Pressure Regulating Valve 11HC
Figure 008
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When the downstream pressure in chamber C3 reaches the set regulation value, the diaphragm M1 closes the poppet valve C. The pressure in chambers C4 and C2 increases (these two chambers are at the same pressure through the restrictor G2) to stop the valve opening. Downstream pressure in chamber C3 modulates the pressure in chambers C4 and C2 through the poppet valve C. The actuator piston position controlled by the pressure in chamber C2 corrects the butterfly valve opening to maintain downstream pressure at the set regulation value. During the transient phase (when upstream pressure or flow changes), the diaphragm M2 acts on the the poppet valve C and controls the pressure variation speed in chamber C4 to avoid downstream pressure instability. During the opening function, restrictor G1 reduces the pressure increase speed in chamber C1, while the opposite chamber C2 is subjected to upstream pressure through the check valve V1. This avoids downstream pressure surge during valve opening. When the solenoid is deenergized, chamber C1 is vented more quickly through the restrictor G1 than chamber C2 through restrictor G2. Therefore the differential pressure C2-C1 added to the return spring effort moves the actuator piston to close the butterfly valve. The inlet port to the regulator is designed to avoid ingestion of dust into the sensing line. It consists of a tube with two lateral orifices that face downstream to the airflow, which senses the inlet pressure. The outlet port vents the regulator to the outlet duct of the valve, whose pressure is used as a measure of regulated pressure. This venting is done through lateral holes of a venturi positioned after the butterfly valve to compensate for turbulence and variations in the airflow.
6. Operation/Control and Indicating________________________________ (Ref. Fig. 005)
A. AFT Cargo-Compartment Temperature-Selector The AFT cargo-compartment temperature-selector 15HC is installed on panel 22VU in the cockpit. The temperature in the AFT cargo compartment is controlled to between 5 DEG.C (41.00 DEG.F) and 26 DEG.C (78.80 DEG.F) in heating mode. 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). Turning the selector knob to the right or left will select any temperature between the above temperatures. When the selector knob is pointing to the 12 o'clock position, the temperature in the cargo compartment is selected to about 15.5 DEG.C (59.90 DEG.F). The heating controller 10HC limits the temperature in the inlet duct to a maximum of 70 DEG.C (158.00 DEG.F).
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B. Hot-Air Switch The hot-air supplied to the pressure regulating-valve 11HC is unconditioned bleed-air from the downstream side of the flow control valves. The HOT-AIR switch (16HC) installed on panel 22VU in the cockpit, controls the pressure regulating-valve.
7. BITE Test_________ (Ref. Fig. 009)
A. CHC Power-up Test
(1)
Conditions of Power-up Test Initialization
(a)
How long the computer must be de-energized:
-200 ms
(b)
A/C configuration:
-A/C on ground
(2)
Progress of Power-up Test
(a)
Duration:
-28 s
(b)
Cockpit repercussions directly linked to power-up test accomplishment (some other repercussions may occur depending on the A/C configuration but these can be ignored):
-Trim air valve cycling on ECAM system display
(3)
Results of Power-up Test
(a)
Test passed:
-none
(b)
Test failed:
-
ECAM warning:
COND AFT CRG HEAT FAULT
-
ECAM COND page:
hot air valve displayed in amber
-Maintenance status:
AFT cargo heat
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B. CFDS Maintenance Messages
(1) The AFT cargo-compartment heating-controllers (10HC) sends failure data detected by its BITE to the Centralized Fault Display System (CFDS). A possible failure can be class 1, class 2 or class 3.
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