Air Systems Flashcards
What sources supply air to the bleed air (pneumatic) system?
Engines, APU, or an external pneumatic air cart/source (on the ground)
SH 2.010 pg 1
What systems rely on bleed (pneumatic) air for operation?
WHAP PNES
Air Conditioning/Pressurization Wing Thermal Anti-Icing Engine Thermal Anti-Icing (respective engine bleed air) Engine Starting Hydraulic Reservoir Pressurization Water Tank Pressurization Nitrogen Generation SH 2.010 pg 1
What is the purpose of the Engine Bleed Air Valve, and how is it operated?
Acts as a pressure regulator and shutoff valve
–*DC controlled, pneumatically actuated
Automatically closes when fire handle pulled & during engine start (isolate and ventilate)
SH 2.010 pg 5
What is the purpose of the Precooler System?
Precools the air
SH 2.010.3
What causes Bleed Trip Sensors to automatically close the Engine Bleed Air Valve?
Overheat or overpressure.
Associated with a Master Caution and AIR COND annunciator.
SH 2.010 pg 5
How is the bleed trip condition reset?
Push the TRIP RESET switch
(Condition must no longer exist for a successful reset).
SH 2.010 pg 5
What do the WING-BODY OVERHEAT, BLEED TRIP OFF, and DUAL BLEED amber lights
on the Bleed Air Panel indicate? What causes these lights to illuminate?
WING-BODY OVERHEAT = leak in a critical area air duct (no reset possible)
BLEED TRIP OFF = overheat or overpressure (TRIP RESET possible)
DUAL BLEED = indicates APU bleed valve is open and
- engine #1 bleed switch is on, or
- engine #2 bleed switch is on and isolation valve is open
SH 2.010 pg 8
What is the purpose of the APU Bleed Air Valve, and how is it operated?
To provide bleed air to the left duct.
*DC powered, pneumatically operated.
SH 2.010 pg 7
What is the purpose of the Isolation Valve?
The Isolation Valve isolates the left and right bleed air ducts during
normal operations, when in the closed position.
SH 2.010 pg 8
What do the Isolation Valve positions CLOSE, OPEN, and AUTO do?
*opens when any L/R pack or L/R engine bleed turned OFF (four corner
switches)
CLOSE = forces valve closed, isolating L & R bleed air ducts
OPEN = forces valve open, allowing flow between L & R
AUTO = valve will be closed when
- Both engine bleed are switches are ON and
- Both Air Conditioning PACK switches are in AUTO or HIGH
SH 2.010 PG 8 and bleed air app
*How do the Engine BLEED Air or Air Conditioning PACK switches impact operation of the
Isolation Valve?
Turning any engine bleed air switch or pack switch OFF will OPEN the valve
*Isolation valve position is not affected by the APU BLEED AIR Switch
SH 2.010 PG 8 and bleed air app
Where is the external pneumatic air connection located?
Located on the right side of the aircraft (immediately aft of the right landing
light) underneath a quick release access panel.
SH 2.010 pg 6
What is the path of conditioned air from an external (ground) source?
Pre-conditioned ground air enters directly into the mixing manifold downstream
of the packs.
SH 2.020 pg 1
When connected to external air, which position should the PACK switches be in?
OFF - with external air connected, packs must be OFF (limitation)
Leaving packs on will reduce efficiency of external cart. Flight deck controls are ineffective for external preconditioned air.
SH 2.020 pg 15
What is the primary source of conditioned air to the Flight Deck? To the passenger cabin?
Flight Deck = Left pack
Pax Cabin = Right pack and some left pack air
through mix manifold
SH 2.020
How is the forward cargo compartment heated?
Exhaust air from the equipment cooling fans
SH 2.020 pg 16
How is heat provided to the aft cargo compartment?
Aft cargo is unheated.
What do the PACK amber lights on the Bleed Air Panel indicate? What causes these lights to
illuminate?
PACK (with MC/AIR COND) = overheat condition OR fault of both primary and
secondary controllers (TRIP RESET possible)
PACK (on recall only) = failure of primary OR standby controller
SH 2.020 pg 5
What happens with the Master Caution light during a failure of Primary pack control? Standby
pack control?
Nothing - single failure is only shown in recall
Both fail? MASTER CAUTION and AIR COND annunciator with PACK light
A single pack in high flow mode can maintain pressurization and comfort up to what altitude?
41,000ft
SH 2.020 pg 2
** SE PACK is 25,000 if MEL
Explain the auto logic for high airflow during normal operations and with a pack or engine
failure.
In AUTO: Pack fails or engine fails? Automatically goes into HIGH with the flaps
up
SH 2.020 pg 2, but use Bleed Air App schematic and click on the info button on the
pack for the best information
What controls pack temperature control?
Zone that needs the most cooling is what decides what the packs do, then the
Trim Air System regulates the other 2 zones
SH 2.020 pg 2
What is the purpose of the recirculation fans?
Reduces demand on the bleed air system and recirculates air.
RIGHT recirc fan takes air from holes in floor and runs it to mix manifold
LEFT recirc fan takes in air from the air conditioning distribution compartment
SH 2.020 pg 9
What is the purpose of the Equipment Cooling System?
-Cools electronic equipment in the Flight Deck and the
E/E bay.
-Smoke removal (drives to full open and allows smoke to escape)
-Heats FWD cargo compartment (keeps the puppies warm)
SH 2.020 pg 16
