Air Conditioning Flashcards
How are the zone temperatures individually controlled?
- Temperature regulation is controlled by 2 air conditioning system controllers. - Temperature regulation is optimized via the hot air pressure regulating valve, and the trim air valves that add hot air, tapped upstream of the packs, to the mixing unit air.
What controls the packs and TAVs?
Pack operation is controlled by air conditioning system controller signals.
What happens to the system during engine start?
- If the crossbleed valve is closed, the valve located on the staring engine side immediately closes, when the mode selector is set to IGN or CRANK. 2. If remains closed on the starting engine side (provided the crossbleed valve is closed) when: a. MASTER SW on b. Start valve is open c. N2 <50% 3. On the ground, reopening of the valves is delayed for 30secs to avoid a supplementary pack closure cycle during 2nd engine start.
What happens when a duct overheat occurs?
- The FAULT light come son amber. - ECAM caution, when duct overheat is detected. - The fault circuit detects an overheat when the duct temperature reaches 80 degrees once.
When does the Pack Ram Air Inlet Flap close?
T/O: takeoff power is set and the main landing gear struts are compressed. LDG: as soon as the main landing gear struts are compressed, as long as speed is greater or equal to 70kts. They open 20sec after speed drops below 70kts.
What 3 conditions could cause the Pack Flow to be Higher than the selected on the overhead panel?
- In single-pack operation - When the APU is suppling bleed air - When temperature cannot be satisfied
The compartment temperature controllers can be set to what range of temps?
18 – 30 degrees Celsius (64 – 86 degrees Fahrenheit)
What happens if an ACSC has a LANE failure?
No effect, as the second lane takes over.
What happens if an ACSC has a double LANE failure?
Related pack is lost (ACSC1 – flight deck, ACSC 2 – cabin), Hot Air Pressure Regulating Valve and associated Trim Air Valves close.
When does a Pack Overheat FAULT light, (on OHP) extinguish?
When the temperature drops < 70 degrees and the flight crew selects OFF.
What happens when the Ram Air Pushbutton is selected ON?
If the DITCHING p/b, on the CABIN PRESS panel is in normal position: - Ram Air Inlet opens - If delta P is greater or equal to 1 PSI, no emergency Ram Air flow in (Closed) - If delta P is less than 1 PSI, outflow valve opens to 50% when under automatic control. It does not automatically open when it is under manual control. Emergency RAM airflow is directly supplied to the mixer unit.
What limitations apply to the opening of the Ram Air Valve?
Only open if differential pressure is lower than 1 PSI.
The LO/ECON pack flow setting thresholds.
A320 LO: if the number of occupants is below 141. A321 ECON: if the number of occupants is below 168.
What is the function of a pack & how does it achieve this?
Function - to cool hot pneumatic bleed air. Achieved by; Energy is removed by an Air Cycle Machine and also by Heat Exchangers which are themselves cooled by Ram Air.
What does the Pack Bypass valve do and what controls it?
It determines how much air passes through the Pack Air Cycle Machine and Main Heat Exchanger & how much bypasses them. This determines Pack output temperature. The Bypass Valve is controlled by the two channel Pack Controller. DSC-21-10-30
What does the Pack Flow Control Valve do? How is it operated? Which component controls it?
- it varies the rate of Air-flow to the pack - Electrically signalled closed (engine start, Fire p/b, o/heat,) Pneumatically opened by Upstream Pneumatic Pressure. - it is controlled by the onside Pack Controller DSC-21-10-20 DSC-21-10-30
What components are controlled by the Pack Controllers?
- Pack Flow Control Valve - Pack heat exchanger ram air inlets.
To where does the Emergency Ram Air inlet connect and what condition must be satisfied before it will open?
- mixer unit - Delta P < 1 psi
How is the Hot Air Pressure Regulating Valve Operated?
Electrically signalled, Pneumatically opened by Upstream Air Pressure.
How are the Trim Air Valves operated; what controls them?
- Electrically signalled & operated. - All 3 TAVs are controlled by the single Zone Controller.
When do Pack Ram Air Inlet Flaps Open & Close?
- CLOSE for Take-off when TOGA/FLEX thrust set - OPEN at Lift Off - CLOSE on Landing on touchdown - OPEN at 70 knots +20 seconds. DSC 21-10-30
With Pack Flow Rate selected to NORM; Give two occasions when Pack Flow rate will be HIGH.
- Single Pack Operations - APU supplying Bleed Air DSC 21-10-30
In Normal Operations, what temperature demand is signalled by the Zone Controller to the Pack Controllers?
That the packs both output air at the lowest demanded zone temperatures. DSC-21-10-30
What happens to zones requiring warmer air than the lowest demanded zone temperature?
Trim Air Valves will open to add Hot Air to the Air supplied to that zone.
What is the temperature range of the Flight Deck temperature controls?
18 deg C to 30 deg C.
The Zone Controller has two channels: Primary & Secondary. What happens if the Primary Channel Fails? What is this mode of Temperature Regulation called & how is it shown?
- The Secondary channel is unable to read the Flight Deck Temp Selectors or control the TAVs, although it can sense zone ambient temperatures. It assumes that all zones should be at 24 deg C, so commands the Pack Controllers to Output Air at appropriate temperatures to achieve this. - This is called ALTN MODE - Indicated by caption ALTN MODE on the COND SD. NB: When in ALTN mode control, the two packs may be running at different temperatures. REF: cannot find an official one (Alteon Question Pack.)
What happens if the Zone Controller Secondary Channel (only) fails?
Redundancy is lost, but System Temperature Control is not otherwise affected.
What happens if both Zone Controller Channels fail? What is this mode of Temperature Regulation called & how is it shown?
- The Zone Controller is unable to send control signals to the Pack Controllers. In the absence of such incoming signals, the Left Pack outputs air at a fixed 20 deg C and the Right at 10 deg C. There are no ECAM AirCond parameters. - This is called PACK REG - Annotated as PACK REG on the COND SD.
Each Pack Controller has two channels: Primary and Secondary. What is the effect of failure of the Primary?
The secondary channel continues to control the pack to the Temp signalled by the Zone Controller. However, Pack Valve Flow Rate will be fixed at the current setting.
