Air systems/Bleed

Question 1

What sources supply air to the bleed air (pneumatic) system?

Answer 1

Eng, APU, Ext.

Question 2

What systems rely on bleed (pneumatic) air for operation?

Answer 2

Air Cond/Press, Wing/Engine Anti-Ice, Engine Starting, Hyd Res Press, Water Tank Press, NGS

Question 3

What is the purpose of the Engine Bleed Air Valve, and how is it operated?

Answer 3

Pressure regulator and shutoff valve. DC-controlled, pressure-operated.

Question 4

What is the purpose of the Precooler System?

Answer 4

Regulates (cools) the temp of the Eng bleed air down via an air to-air heat exchanger.

Question 5

What causes Bleed Trip Sensors to automatically close the Engine Bleed Air Valve?

Answer 5

Excessively high engine bleed air temp, or pressures. Illuminates BLEED TRIP OFF light, AIR COND
annunciator, and MASTER CAUTION.

Question 6

How is the bleed trip condition reset?

Answer 6

Push the TRIP RESET switch if Condition must no longer exist

Question 7

What do the WING-BODY OVERHEAT, BLEED TRIP OFF, and DUAL BLEED amber lights on the Bleed Air Panel indicate?

Answer 7

a. WING-BODY OVERHEAT: a duct leak in a critical area
b. BLEED TRIP OFF - Sensors around the Bleed air Valve sense an over temp/pressure
c. DUAL BLEED – 2 sources on left duct, APU and Eng 1 bleed, or Eng 2 bleed and isolation valve open

Question 8

What is the purpose of the APU Bleed Air Valve, and how is it operated?

Answer 8

APU bleed air to the left duct. DC-controlled, pneumatically operated. APU Bleed Switch

Question 9

What is the purpose of the Isolation Valve?

Answer 9

Isolates the left and right bleed air ducts during normal ops

Question 10

What do the Isolation Valve positions CLOSE, OPEN, and AUTO do?

Answer 10

a. CLOSE: remains closed
b. OPEN remains open
c. AUTO - Isolations valve will auto closes when Both engine bleed ON and Both PACKs AUTO/HIGH and
switching any to OFF. (four corner switches)

Question 11

How do the Engine BLEED Air or Air Conditioning PACK switches impact operation of the Isolation Valve?

Answer 11

a. Turning any engine bleed air switch or pack switch OFF will OPEN the valve

Question 12

Where is the external pneumatic air connection located?

Answer 12

e right side of the aircraft (immediately aft of the right landing light)

Question 13

What is the path of conditioned air from an external (ground) source?

Answer 13

Directly into the mixing manifold

Question 14

. When connected to external air, which position should the PACK switches be in?

Answer 14

off

Question 15

What is the primary source of conditioned air to the Flight Deck?

Answer 15

Left pack

Question 16

To the passenger cabin?

Answer 16

Right pack

Question 17

How is the forward cargo compartment heated?

Answer 17

Exhaust air from the E/E bay via equipment cooling fans

Question 18

The aft cargo compartment?

Answer 18

Aft cargo is unheated

Question 19

What do the PACK amber lights on the Bleed Air Panel indicate?

Answer 19

Overheat or failure of a pack controllers

Question 20

What causes these lights to illuminate?

Answer 20

Immediately for overheat or dual controller failure, during recall for single pack controller failure

Question 21

. What happens with the Master Caution light during a failure of Primary pack control?

Answer 21

Nothing.

Question 22

. Standby pack control?

Answer 22

Nothing. Single failure is only shown in recall

Question 23

. A single pack in high flow mode can maintain pressurization and comfort up to what altitude?

Answer 23

41,000

Question 24

Explain the auto logic for high airflow during normal operations and with a pack or engine failure.

Answer 24

In AUTO: Pack fails or engine fails? Automatically goes into HIGH with the flaps up

Question 25

What controls pack temperature control?

Answer 25

Zone that needs the most cooling is what decides what the packs do, then the Trim Air System regulates the other 2 zones

Question 26

What is the purpose of the recirculation fans?

Answer 26

a. Reduction of bleed air demand and recirculates air b. 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

Question 27

What is the purpose of the Equipment Cooling System?

Answer 27

a. Cools electronic equipment in the Flight Deck and the E/E bay. Warms Fwd cargo bay, Smoke removal

Question 28

What does the EQUIP COOLING OFF (amber) light indicate?

Answer 28

Low flow from Equipment Cooling Fan.

Question 29

What causes the AUTO FAIL and OFF SCHED DESCENT amber lights to illuminate?

Answer 29

AUTO FAIL - one or both pressurization channels are INOP b. OFF SCHED DESCENT - descent without reaching initial cruise altitude.

Question 30

How does the primary heat exchanger lower the bleed air temperature?

Answer 30

Ram air flow augmented with an induction impeller driven by an extension of ACM shaft.

Question 31

What is indicated by a bright blue RAM DOOR FULL OPEN light? Dim blue? Extinguished?

Answer 31

Bright Ram door is in the full open position Dim=Never happens Extinguished= closed or modulating

Question 32

What do the ALTN (green) light and MANUAL (green) light on the Cabin Pressurization panel indicate?

Answer 32

a. ALTN - Alternate mode activated b. MANUAL - manual mode

Question 33

What causes these lights to illuminate?

Answer 33

a. ALTN- manually selected or main CPC unit has failed b. MANUAL- mode selected to manual pressurization

Question 34

What does the Pressurization Mode Selector do?

Answer 34

Selects either auto, alt, or man pressurization

Question 35

Describe the 3 temperature control zones

Answer 35

Control cabin (cockpit), Forward cabin, Aft cabin

Question 36

. What does an illuminated ZONE TEMP (amber) light indicate?

Answer 36

Overheat in associated ducting, or double controller failure

Question 37

What happens with the Master Caution light when ZONE TEMP illuminates?

Answer 37

Master caution illuminates. Not inhibited

Question 38

What is the purpose of the Mix Manifold?

Answer 38

Joins recirculated air with conditioned air from PACK, distributes to pax cabin

Question 39

On the Cabin Pressurization Panel, what do the FLT ALT indicator and LAND ALT indicator display?

Answer 39

a. FLT ALT- scheduled cruise alt for pressurization b. LAND ALT- Landing airport altitude (schedule)

Question 40

What are indications and impact of a panel failure?

Answer 40

Display 8888888, if all is normal nothing is affected. If Display ------------ controller failed, manual mode

Question 41

What is indicated by the CABIN ALTITUDE (red) light and the Cabin Altitude Warning Horn? How can this horn be silenced?

Answer 41

>10000’ cabin alt. Alt horn cutout by cabin alt gauge silences.

Question 42

What does AUTO FAIL light indicate?

Answer 42

Dual controller failure or Single controller fail if ALTN is on