Air Systems Flashcards
What are the sources of air to the Bleed Air System?
- Engines
- APU
- External Pneumatic Air
Cart.
What is the purpose of the Air Supply Controller (ASC)?
The ASC digitally controls the output of the 4th and 10th stage pneumatic air in response to bleed air demands.
What causes the engine bleed air valve to automatically close?
High Temperature (254 C) or High Pressure (170 psi for 5 seconds).
What does the illumination of the BLEED (amber) light indicate?
- Bleed sensors have automatically closed the engine bleed valve due to excessively high engine bleed air temperature or pressure, or
- a failure within the Bleed Air System that is not resettable, or
- an incorrect bleed air configuration is detected 45 seconds after flaps reach the UP position.
What will cause the automatic closure of the APU Bleed Valve?
- Shutting down the APU.
- The valve closes automatically when the APU is shut down, regardless of BLEED switch position.
What is the position of the isolation valve with the ISOLATION VALVE switch in AUTO?
- In AUTO, the Isolation Valve is closed when:
o Both Bleed Air Switches are ON, and
o Both Air Conditioning PACK switches are
in AUTO or HIGH.
What does the illumination of the DUAL BLEED (amber) light indicate?
- When the APU Bleed Air Valve is open and:
o Engine Number 1 Bleed Switch is
positioned to ON, and / or
o Engine Number 2 Bleed Switch is
positioned to ON with the Isolation Valve
OPEN. - This condition exposes the APU to engine bleed air back pressure should the APU Check Valve fail.
- Note the discrepancy:
o APU Bleed VALVE.
o Isolation VALVE.
o Engine Bleed SWITCH.
In the event of a single pack failure at altitude, the remaining PACK is capable of maintaining cabin pressure and comfort up to what altitude?
Service Ceiling.
What causes a pack to automatically switch to high airflow?
When the aircraft is airborne with flaps fully retracted, both PACK switches in AUTO, and ENG Bleed switches to ON, if one pack fails or a pack switch is selected to OFF, the remaining pack automatically switches to high air flow to increase ventilation.
How many controllers does each PACK have?
Both packs have two integrated pack/zone electronic controllers. Each controller has a digital primary channel to control its respective pack and an analog channel that provides backup control for the opposite side pack.
What does the illumination of the PACK (amber) light indicate?
- Indicates a failure of both the primary and standby pack controls for the same pack, or
- failure of the pack valve to open when commanded, or
- incorrect configuration after take-off.
- a PACK overheat.
- During Master Caution Recall, indicates a primary or standby pack control failure exists. The light extinguishes when the Master Caution System is reset.
Do the Flight Attendants have any control of cabin temperature?
Yes. Flight attendants may adjust the forward and aft cabin zones +/- 3 degrees Celsius.
How is the failure of either the primary or standby PACK controller indicated on the ground?
- Illumination of the MAINT (amber) light along with the Master Caution and OVERHEAD annunciation after landing indicates the failure of one controller.
What provides cooling air for the PACK systems?
Ram Air System provides cooling air for the Air Conditioning Pack Heat Exchangers. Operation is controlled through the positioning of the Ram Air Inlet Doors. They move to the full-open position for maximum cooling:
o on the ground, or
o during slow flight with flaps extended.
How is a supply duct overheat indicated?
Illumination of the ZONE TEMP (amber) light.
