CHAPTER 21 Flashcards
How many separate cabin temperature aircraft zones are
supplied from the mixer unit?
Cockpit, Forward cabin and aft cabin.
What is the function of the cabin recirculation fans?
The two cabin recirculation fans are installed to reduce the bleed air demand and therefore save fuel.
How is a warmer demand processed for individual zones?
For the zones in which warmer temperatures are necessary, the ACSC sends a signal to the related TRIM AIR VALVE to open. Hot air mixes with the Mixer Unit discharge air and the temperature increases.
Where is the mixer unit located on the aircraft?
The mixer unit is installed at the rear of the forward cargo compartment.
What is the purpose of the mixer unit?
It mixes air from the packs and re-circulated air from the cabin before distribution to each zone.
What supplies cooling air when the aircraft is on the ground?
During aircraft operation on ground, the ACM FAN is used to supply
cooling air around the primary and the main heat exchangers.
In flight what position will the ACM FAN be in?
In flight with ram air available, the fan will be bypassed to prevent a negative effect on the ACM operation.
To prevent a pack overheat the ACSC monitors the temperature of what location?
To prevent a pack overheat, the ACSC monitors the COMPRESSOR DISCHARGE TEMP SENSOR.
Pack temperature in normal conditions is maintained at what temperature?
Pack temperature controls up to 180°C for normal operation.
What causes a pack FAULT light comes on with regards to compressor outlet temperature?
The pack FAULT light comes on in if there is compressor outlet temperature of 260°C.
The pack discharge temperature sensor will cause an overheat warning at which temperature?
The pack discharge temperature sensor gives pack overheat warning indications if the pack outlet temperature exceeds 88°C.
What controls the Avionics Equipment cooling system?
The Avionics Equipment Ventilation Computer (AEVC) ensures control and monitoring of the AVNCS ventilation system.
How does the AEVC control the Avionics Equipment cooling system?
The AEVC will change the system configuration depending on whether the A/C is on ground or in flight and on A/C skin temperature. The system is automatic no crew action is required.
In order for the Avionics Equipment Ventilation Computer (AEVC) to operate automatically what switch settings are required?
The BLOWER and EXTRACT P/Bs must be in AUTO position.
What is the normal cabin altitude maintained at?
8000ft
What cabin altitude will CABIN ALTITUDE warning be activated?
9550ft
What cabin altitude will PAX SIGNS be activated?
11300ft
What cabin altitude will cause the outflow valves to automatically close?
15000ft
What backup devise is fitted to ensure that sufficient fresh air is delivered to the cockpit in case of pack 1 failure.
An electrically operated mixer unit flap is installed to ensure that sufficient fresh air is delivered to the cockpit in case of pack 1 failure.
When the aircraft is on the ground with the electrical systems powered, the avionics ventilation system is normally in what configuration?
When the aircraft is on the ground with the electrical systems powered, the avionics ventilation system is normally in the OPEN configuration. In this configuration, the ventilation BLOWER fan pulls air in from the open Skin Air Inlet Valve on the LH side of the fuselage.
If the Skin Air INLET or OUTLET valve fails on the ground how is the Avionics systems prevented from overheating?
If the Skin Air INLET or OUTLET valve fails on the ground, either valve may be manually operated to the OPEN position. Before flight, the
failed valve must be deactivated in the proper configuration.
How is the air dispersed from the main cabin in a smoke detection situation?
Air from the main cabin is drawn down into the cargo compartment by the extract fan or by differential pressure in flight. After circulating through the compartment, the air is discharged overboard.
