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32 Cards in this Set
- Front
- Back
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Which pack supplies COCKPIT, FWD CABIN & AFT CABIN?
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Conditioned air from the left pack flows directly to the cockpit (20%). Excess air from the left pack (80%) and air from the right pack and recirculation fans supply the cabin via the mix manifold
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Is two pack operation from a single bleed source allowed?
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It is not recommended due to the excessive bleed requirements.
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How many zones and controllers are there?
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There is 3 zones:
- CONT CAB (flt deck) - FWD CAB - AFT CAB These are controlled by 2 controllers, left and right. |
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Explain what each controller controls. (LEFT & RIGHT)
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LEFT
- controls aft cabin - backup for cockpit - left pack temp control valve - right stby temp control valve - left ram-air door RIGHT - controls forward cabin - primary cockpit control - right temp control valve - left stby temp control valve - right ram-air door |
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What does ZONE TEMP light indicate.
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ZONE TEMP light indicates:
CONT CAB - duct overheat - cockpit primary and stby controllers failed FWD CAB/AFT CAB - duct overheat DURING MASTER CAUTION RECALL: CONT CAB - failue of primary or stby temp controller (auto switching) FWD CAB/AFT CAB - failure of associated temp control ( temp selectors will operate normally but the temps of the 2 zones will be averaged) |
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SMOKE in the cockpit caused by the pack, could be from which side?
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The LEFT pack as it supplies air directly to the cockpit.
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What does a PACK light indicate?
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The primary and stby pack controls have failed or there is a pack overheat.
If PACK light illuminates on MASTER CAUTION recall: - indicates primary or stby pack control has failed and auto switching to remain controller has occurred |
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Explain air flow with PACK SWITCH in AUTO.
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In AUTO:
- the pack provides noraml air flow - with one pack valve closed, the other pack auto switches to HIGH (inhibited on the ground or inflight with flaps extended to ensure adequate power for single engine operations) |
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What is RAM AIR used for?
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RAM AIR is used to cool the heat exchangers in the air con system.
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RAM DOOR FULL OPEN light indicates what?
When is the deflector door extended? |
RAM DOOR FULL OPEN indicates the ram air door is fully open, providing maximum cooling. Usually occurs on the ground or inflight with flaps extended.
Deflector door extends on the ground to prevent FOD entering the ram air system. |
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What is the job off the recirculation fans?
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The recirc fans reduce bleed demands by increasing the volume of air in the mix manifold. It also reduces air con system pack load and creats low pressure area to pull EE compartment hot air to radiate around fwd cargo compartment.
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With the RECIRC FANS in AUTO when will they automatically shut off?
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In flight
- if both packs are operating and either pack is switched to HIGH, the left RECIRC FAN will shut off. - the right recirc fan will operate in flight unless both packs are in HIGH. On the ground - the left recirc fan operates unless both PACK switches are in HIGH - the right recirc fan operates even if both PACK switches are in HIGH |
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Explain the Equipment Cooling in the ground configuration.
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On the ground, or with cabin differential pressure less than 1 psi, the exhaust fan air is routed thru an overboard exhaust valve and dumped overboard.
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Explain how the supply and exhaust fans work.
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The supply fan provides cool air to the flight deck displays and electrical equipment in the E & E bay.
The exhaust fan collects and discards warm air, either overboard or around the FWD cargo compartment, from behind the flight displays, E & & bay, CB panels and behind the overhead panels. |
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If an over tempertaure occurs, associated with equipment Cooling system, how is it indicated on the ground?
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A warning horn is sounded in the nose wheel gear.
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What does EQUIP COOLING SUPPLY/EXHAUST OFF light indicate?
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EQUIP COOLING SUPPLY/EXHAUST OFF light indicates:
- a failure of the associated fan (light will extinguish once ALTN source is selected) - if light remains illuminated, indicates both fans have failed (NG - if flight is continued for >30 mins with: - supply fan inop, Capt loses DU's & lower DU. - exhaust fan inop, FO loses DU's & upper DU. ) |
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What power source runs the main outflow valve?
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3 DC motors
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What is maximum differential pressure?
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9.1 psi
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How many outflow valves are fitted?
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One, Main outflow valve
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Explain the 3 modes of pressuristaion on the NG and which power source is used?
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AUTO - automatic, normal mode. If failure occurs automatic switching occurs. Uses DC motor
ALTN - automatic, back up controller. Automatically switched to if failure occurs. Uses DC motor MAN - manual control using DC motor |
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From where is altitude and barometric information supplied for pressurisation?
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Aircraft altitude is sensed by ADIRUs.
Barometric corrections are supplied from both CAPT and FO altimeters. |
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Explain the airflow from cabin to outflow valve.
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Air flows from the cabin via foot level grills, around the aft cargo compartment (for heating) and out via the main out flow valve.
Inlfight cabin air is taken from the cabin thru instruments and E & E bay, via closed foverboard exhaust valve and around fwd cargo compartment (for heating). The overboard exhaust valve remains closed inflight, unless both pack switches are in HIGH and the recirc fan is off. On the ground or inflight with low cabin diff psi, the overboard exhaust valve is open and dumped overbaord prior to the fwd cargo compartment. |
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Why is the cabin slightly pressurised on the ground prior to departure?
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The ground pressurisation makes the transition to pressurised flight more gradual for pax and crew, and also gives the system better response to ground effect pressure changes during take-off.
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When is cruise mode activated? What is the constant differential pressure schedule?
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Cruise mode is activated when aircraft climbs within 0.25 psi below selected FLT ALT. The controller schedules a constant differential pressure schedule:
- 7.45 psi to 28 000' - 7.8 psi 28 000' - 37 000' - 8.35 psi > 37 000' |
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What does OF SCHED DESCENT light indicate?
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Aircrafts descends before reaching cruise mode/relay trip off.
( If OFF SCHED DESCENT occurs, controller programs cabin to land at take-off elevation without further pilot inputs.) |
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When does the pressurisation DES mode activate?
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When aircraft dexcends 0.25 psi below FLT ALT
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What are the 4 conditons which cause the AUTO FAIL light?
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AUTO FAIL light indicates:
- loss of DC power - controller fault - excessive rate of cabin psi change (> 2000 fpm) - high cabin alt (> 15 800') |
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How is ALTN mode selected and how does it differ from AUTO?
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ALTN mode is automatically selected when an AUTO FAIL occurs.
The AUTO FAIL remains illuminated until ALTN mode is selected, then the green ATLN light remians illuminated. ALTN mode is automatic just like AUTO (requires no pilot inputs) |
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How does the cabin 'pre-pressurise' without a FLT/GRD switch?
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On the ground at low power settings, the outflow valve is held open to depressurise the aircraft.
On the ground at higher power settings, the outflow valve is moved towards closed to pressurise the aircaft for takeoff. |
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With the TRIM AIR switch in the OFF position, how is cockpit/cabin temp regulated?
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With TRIM AIR switch in OFF, the packs independently regulate the cockpit/cabin temp.
Left pack regulates the cockpit temp using the CONT CAB setting. Right pack regulates the cabin temp using the cooler of the FWD CAB or AFT CAB settings. |
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What can the TRIP RESET switch reset?
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BLEED TRIP OFF
PACK ZONE TEMP |
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What does BLEED TRIP OFF light indicate?
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Excessive bleed temp or pressure is sensed. Engine bleed closes automatically. A reset is available once temp ro pressure reduces.
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