ATR 72 - Air Conditioning
The air intended for air conditioning and pressurization is pressurized by engines compressors and delivered through the bleed valves.
Incorrect position of a turbo fan shutoff valve leads to the automatic opening of the associated pack valve.
Incorrect position of a turbo fan shutoff valve leads to closure of associated pack valve.
Which areas of the ATR 72 are ventilated by the flow of ambient air that is recirculated (underflow) to the pressurized compartment, or ducted overboard?
DUCT indicator - For the selected compartment, it indicates the temperature of the conditioned air before entering the duct.
It indicates in deg. C the temperature of the conditioned air before leaving the duct.
In case of smoke in forward cargo compartment, flight deck air extraction duct can be closed with a lever on right side maintenance panel in order to avoid contaminated air suction to the flight deck.
PACK VALVE pb - When pushed on associated PACK VALVE is open if:
A 6 second-delay has been provided on right pack valve for passengers comfort purpose.
The pack valve is:
If a pack valve is closed or inoperative:
Air is extracted by a fan which can operate at different speeds depending on flight deck temperature. Rotation speed is minimum below _____ , maximum above 52 deg.C (126 deg.F) and varies linearly between these values.
RECIRC FAN pb - When the pb is pressed in the fan runs. Recirculation of a part of the cabin air to supplement the conditioned air supply is provided. If temperature measured at cabin floor level is lower than 13 deg.C (55 deg.F), high speed is automatically stopped.
If temperature measured at cabin floor level is lower than 13 deg.C (55 deg.F), high speed is automatically selected.
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The butterfly valve has:
In automatic mode, each pack discharge temperature is controlled by an electronic temperature controller which computes the position of the temperature control valve taking into account:
What is the electrical power supply for the packs?
The air conditioning system is equipped with two packs which regulate air flow and temperature as required. The packs cool, remove moisture and pressurize the bleed air. The two packs are installed _____ and operate automatically and independently.
Temperature Control - In manual mode, each pack temperature control valve is controlled directly by the COMPT TEMP knob and limited by:
RECIRC FAN pb - The FAULT light will come on amber and the caution message 'AIR RECIRC FAN 1(2)' will be displayed on the EWD. It will be associated with a Master Caution and a single chime. This will occur if:
Double Temperature Indicator (DTI) - The Double Temperature Indicator (DTI) is a dual indicator, which enables the crew to monitor the duct inlet (DUCT) and the compartment (COMPT) temperature in the selected zone (Cockpit or Cabin). At power on, the DTI is set at full bright while dimming input is not available. Once dimming input is available (AC available) the indicator is automatically dimmed to the correspondent level.
The DTI is automatically full dimmed when the aircraft AC power is shut down (Ground AC power supply disconnection or during stop with Hotel mode), despite the brightness knob selection until AC Power is recovered. The flight crew should not consider this behavior as a failure of the DTI. DUCT temperatures are still monitored and FWS AIR DUCT 1 (2) OVHT alerts are also available. The cabin compartment temperature is available on SD Cabin page.
Only when OVBD VALVE AUTO MODE is selected, EXHAUST MODE pb may be used to control OVBD valve in a partially CLOSE position. This action is required in case of fan failure in order to create cabin differential pressure that generates some cooling air flow.
Only when OVBD VALVE AUTO MODE is selected, EXHAUST MODE pb may be used to control OVBD valve in a partially OPEN position. This action is required in case of fan failure in order to create cabin differential pressure that generates some cooling air flow.
If one pack is inoperative, the other one supplies both compartments through the mixing chamber.
Temperature Control - The system is designed to regulate and limit the temperature of the air discharged from the packs which is supplied to the different zones:
The pack temperature control valves adapt the amount of hot air mixed with the cool air in order to establish the required temperature.
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The pack valve closes automatically when the air downstream of the pack compressor overheats and the temperature is above:
Conditioned air is blown into the cabin by outlet ramps under the overhead bins. It is then evacuated through guides along the cabin side walls at floor level.
The toilet is ventilated by differential pressure through a vent line.
An OVHT caution is provided to the flight crew when the duct temperature is above 92 deg.C (198 deg.F). The pack valve will close immediately.
The pack valve does not close.
What is the electrical power supply for the OVBD valve, U/F valve?
In case of pack overheat downstream of the compressor:
DUCT indicator - For the selected compartment, it indicates the temperature (in deg.C) of the conditioned air before leaving the duct. Duct temperature is automatically limited to a maximum of 88 deg.C / 191 deg.F in AUTO mode only. There is no limitation in MAN mode.
Duct temperature is automatically limited to a maximum of 88 deg.C / 191 deg.F in AUTO mode or MAN mode.
Electric and electronic equipment and the forward cargo compartment are ventilated by _____ which is then recirculated or discharged outside the aircraft.
OVBD VALVE Selector Switch - The safety guard in auto position prevents valve opening control when cabin/exterior dP is _____.
Display on SD Cabin Page - What is the meaning of this information?
Air is cooled by:
- Air is cooled by two ground turbo fans through turbo shutoff valves when IAS is at or below 150 kt and landing gear is retracted for less than 10 min or when IAS is at or below 150 kt and landing gear is extended. - Air is cooled by By ram air when IAS is above 150 kt.