Air Conditioning Flashcards
How many cabin zones are there?
There are 6 cabin zones.
How is the Air Conditioning demand from the cockpit sent to the Pack Controllers?
The Zone Controller (ZC) sends the demand from the cockpit to the Pack Controllers (PC).
What valves do the Pack Controllers (PC) control?
The Pack Controllers control the Pack Flow Control Valves.
What components does the Zone Controller (ZC) control?
The Zone Controller controls the trim air valves and trim air pressure regulating valves.
Where are the safety valves installed, and how many are there?
There are three safety valves installed on the rear pressure bulkhead.
Where is the negative-pressure relief valve located, and how many are there?
There is one negative-pressure relief valve installed on the forward fuselage.
How many outflow valves are there, where are they located, and what controls them?
There are two outflow valves, one forward of the wings and one aft of the wings. Both are controlled by the Cabin Pressure Controllers.
How many motors are on each outflow valve, and what are they used for?
Each outflow valve has three motors: one for each Cabin Pressure Controller (CPC) and one for manual operation.
Where does position feedback from the outflow valves come from, and how is it activated?
Position feedback from the outflow valves comes from CPC 1, which is activated by pin programming.
What does the Residual Pressure Control Unit (RPCU) do after landing?
The Residual Pressure Control Unit (RPCU) fully opens the outflow valves after landing (after 70 seconds if the valves aren’t already open).
Where are the Cabin Pressure Controllers installed?
The Cabin Pressure Controllers are installed on the 800VU rack.
What happens when the Ditching switch is pushed?
Pushing the Ditching switch closes the outflow valves and the emergency ram air inlet flap.
What pressure does the trim air system maintain, and why?
The trim air system maintains around 4 psi to ensure a positive air flow.
How does the Vent Controller (VC) ensure redundancy in case of failure?
The Vent Controller has two lanes, so if one fails, full VC functionality is still maintained.
What additional function do the two cabin re-circulation fans serve?
The two cabin re-circulation fans are also used for Avionics Equipment Ventilation.
What controls the turbofan for pack compartment cooling, and when does it operate?
The AEVC (Avionics Equipment Ventilation Controller) controls the turbofan for pack compartment cooling, which operates only on the ground when the packs are running.
What component is installed in the AEV duct to monitor for sufficient cool air?
The Cooling Effect Detector (CED).
How are the main batteries cooled?
The main batteries have their own cooling via a venturi.
What does the fault light on the Extract pushbutton indicate?
A fault light on the Extract pushbutton indicates an extract fan fault.
What causes airflow through the lavs and galleys while in the air?
Differential pressure via an overboard venturi causes airflow through the lavs and galleys while in the air.
What causes airflow through the lavs and galleys while on the ground?
An extract fan causes airflow through the lavs and galleys while on the ground.
What controls the Lav and Galley ventilation system?
The Vent Controller.
What does the Vent Controller use to determine air/ground status?
The Vent Controller communicates with LGCIU 2 for an air/ground signal and also receives a discrete signal from a differential pressure switch.
What protects the Lav and Galley Extract fan in case of overheat conditions?
A thermal switch protects the Lav and Galley Extract fan in case of overheat conditions.
What monitors for excessive high and low pressure in the Lav and Galley ventilation duct?
A safety switch inside the Lav and Galley ventilation duct.
What happens to the zone controllers if the Vent Controllers or fan become unserviceable?
If the Vent Controllers or fan become unserviceable, the cabin temperature sensors are no longer reliable, so the zone controllers switch to a fixed duct temperature based on the TAT probe indication.
What conditions must be met for Aft Galley Heating to be active?
The galley heating switch must be on, at least one pack must be on, and cargo loading must be off.
What are the two temperature settings for Aft Galley Heating, and how do they function?
The Aft Galley Heating has two temperature settings:
1- Low: Heats one element.
2- High: Heats all three elements.
What happens to the Avail light if the Aft Galley Heating system’s thermal protection is active?
If the Aft Galley Heating system’s thermal protection is active, the Avail light will be off.
What are the two automatic pressurization modes?
The two automatic pressurization modes are External and Internal.
What does External Pressurization Mode use to pressurize the cabin?
External Pressurization Mode pressurizes the cabin according to data from the FMGEC.
What does Internal Pressurization Mode use to pressurize the cabin?
Internal Pressurization Mode pressurizes the cabin according to ambient parameters.
What monitors the three safety valves?
The three safety valves are monitored by the Cabin Pressure Controllers (CPCs).
What happens to the outflow valves if the cabin altitude exceeds 15,000 feet?
A pressure switch on each outflow valve’s automatic actuator will close the outflow valve if the cabin altitude exceeds 15,000 feet.
How are the outflow valve actuators powered?
The two automatic actuators are AC powered, while the manual actuator is DC powered.
What is the maximum cabin altitude for flights less than 2.5 hours?
The maximum cabin altitude for flights less than 2.5 hours is 8,000 feet.
What is the maximum cabin altitude for flights longer than 2.5 hours?
The maximum cabin altitude for flights longer than 2.5 hours is 7,350 feet.
What is the maximum vertical speed for cabin altitude changes?
The maximum vertical speed for cabin altitude changes is 1,000 feet per minute.
When does the pressurization system revert to Internal mode?
The pressurization system reverts to Internal mode in two cases:
1- During a long level off at the top of climb.
2- At the start of descent for 30 seconds while waiting for FMGEC data validation.
