Heating & Aircon Flashcards
The air conditioning system provides what kind of air ?
Conditioned & recirculated air at controlled temperatures
The air conditioning system includes what components?
2x packs,
The trim air system,
2 upper & 2 lower recirculating fans
How does the air conditioning system work?
The air con packs receive hot bleed air from the engines/APU/ground air. Packs cool the bleed air before passing it to the conditioned air manifold. Conditioned air is then distributed to the flt deck & from the manifold to zones A-F in the cabin & to the fwd cargo compartment. Hot trim air from the bleed air system is mixed with conditioned air from the manifold to control the temp in each zone.
Upper & lower recirculating fans augment cabin ventilation. Why is this a good thing?
This allows the packs to operate at reduced flow settings during cruise = it saves fuel!
When the trim air switches are ON & the valves are open the hot trim air mixes with?
Cool conditioned air to modify temperature in all zones, except the zone that requires the coolest air
In the Auto range, the flight deck temperature can be adjusted from ?
18 - 29 degrees C
With the FLT DECK TEMP selector in manual what valve are you actually controlling?
The trim air valve
What is the range of temperature control in the cabin (in auto)?
18 - 29 degrees Celsius
The master temperature setting becomes the baseline temperature for air supplied to the main cabin. With the control at mid position, the master temperature is approximately ……… degrees
24 degrees Celsius
How much can the temperature in individual zones be adjusted, from the master temperature?
+/- 6 degrees from baseline
Individual zones are modified at the ………………………?
Cabin management system panel (in the main cabin)
Where does the air for the upper recirculation fans come from?
The area above the main passenger compartment. The air is recirculated to the zone ducts.
Air for the lower recirculation fans comes from ?
Under the floor area. The fans recirculate the air to the conditioned air manifold.
The upper & lower recirculation fans …………… air flow throughout the cabin.
Augment
Fan operation is automatically controlled by system logic.
How does the equipment cooling system work?
In auto, a supply fan pulls air from the cabin into the system.
Air from the cabin enters the ducts, passes by a smoke detector & low flow sensors.
Smoke detector checks for presence of smoke in the ducts. Sensors detect fan failures by the lack of airflow.
The smoke/override valve, is normally open to allow air flow to flow in the ducts, but closes for certain non-normal conditions.
Cooling air enters the flight deck panels, displays & equipment racks from ………….
Below - & is drawn into the exhaust ducts by a vent fan.
Air is then exhausted into the FWD CARGO COMPARTMENT to heat the compartment when FWD CARGO A/C is OFF & the a/c is airborne.
On the ground, air is either exhausted into the fwd cargo compartment or overboard.
When both in the air & on the ground, the FWD CARGO air conditioning exhaust air vents ………….. ?
Overboard
What is the temperature range for FWD CARGO?
4 - 27 degrees Celsius
Mid range FWD CARGO compartment temperature?
12 degrees Celsius
Are the AFT & BULK cargo compartment temperature selectors accessible from the pilot’s seated position?
No
AFT & BULK cargo compartment heat: Low setting - temperature maintained between ……….
4 - 10 degrees Celsius
The temp control valve opens if the temp in the compartment is < 7 degrees
AFT & BULK cargo compartment heat: HIGH setting; temperature maintained between - …………..
18 - 24 degrees Celsius
What does the BULK CARGO have that the AFT CARGO compartment doesn’t?
A BULK CARGO ventilation fan
The BULK CARGO vent fan operates only on ……………. setting
HIGH
The foot heater is an ……………. heated footplate which only works ………….
Electrically, in the air
Does the electric shoulder heater (in the side window) work on the ground?
No, only in the air.
“EQUIP COOLING” on the EICAS is caused by ?
Low air flow or high air supply temperature
How are ground crews alerted to an equipment cooling issue?
The sound of a ground crew call horn located in the wheel well activating
“EQUIP COOLING OVRD” EICAS advisory message displays if:
Equipment cooling fans inop
Smoke detected in ducts
Low air flow
Systems faults
Standby power operation
Arming FWD CARGO FIRE ARM switch
EQUIP COOLING switch off
If you get a “EQUIP COOLING OVRD” EICAS message you should minimise flight time at ………. altitudes since…….
Low
Since sufficient cooling air for the equipment & displays may not be available. As a result, equipment could fail.
What altitude does the Flight Deck Humidification system automatically operate at ?
Above 26,200 ft & more than 90 mins before TOD
How does the Flight Deck Humidification system work?
It uses water from the potable water system to introduce moisture into the circulation air.
During humidification, minerals precipitating from the potable water may circulate in the cabin, appearing as dust or haze.
What determines the PACK outlet temperature?
The zone requesting the coldest temperature.
Why should the CABIN TEMP selector to be set to mid position?
To allow full temperature range adjustment (65-85 deg F) in cabin zones on Cabin Attendant panel
Why minimise low altitude flight time for EQUIP COOLING OVRD message?
Equipment/displays could fail.
The left air conditioning pack is in standby mode. During descent, the left pack shuts down. What is one possible reason for the pack to shutdown?
The airplane is not in an area of favourable atmospheric conditions.
