Pneumatics

Question 0

What side of the pneumatic sys does the water sys get air from?

Answer 0

L side

Question 1

What does the pneumatic sys supply air to?

Answer 1

The Pneumatic System supplies bleed air to operate the Air Conditioning Systems, Wing and Engine Anti-ice Systems, water system pressurization, hydraulic reservoir pressurization, and to operate the Engine Starters.

Question 2

How do the engine pneumatic start valves work?

Answer 2

The start valves are electrically controlled from the Battery Bus and are pneumatically operated.
Operation is initiated when the Engine Start switches are moved to the GRD position.

Question 3

Which stages of air does the pneumatic sys get air from?

Answer 3

5th stage primary

9th stage if needed

Question 4

Will the bleed valve open if the bleed switch on, and no bleed air available from the associated engine

Answer 4

No, remains closed

Question 5

How do the bleed valves power and operate?

Answer 5

As with most pneumatic valves - DC electrical power activates the bleed valve - but the valve is opened by bleed air pressure.
Therefore this type of valve is electrically controlled but pneumatically operated.
With the bleed switch on and air available from the associated engine, the valve opens

Question 6

What 2 things can cause the bleed valve to close?

Answer 6

The Bleed Valve automatically shuts off pneumatic airflow as a result of a high bleed air temperature signal that is detected downstream of the precooler.
A pressure sensor prior to the bleed valve can also automatically shut off the bleed valve for excessive pressure.

Question 7

What stage air has higher temp and pressure?

Answer 7

The 9th stage air is delivered at a higher temperature and pressure.

Question 8

How is the APU powered and operated?

Answer 8

The APU Bleed Valve is electrically controlled from the battery bus and is pneumatically operated.

Question 9

How does the ISOL VALVE AUTO position work?

Answer 9

In the AUTO position, the Isolation Valve automatically opens when either Pack switch is turned OFF or either engine Bleed Switch is turned OFF.
Thus - in AUTO - if any engine bleed or pack switch is off - the Isolation Valve enables all pneumatic users to receive air from either manifold.

Question 10

Does the APU bleed air valve position effect the ISOL VALVE position?

Answer 10

No

Question 11

What is the logic for the ISOL VALVE?

Answer 11

If all 4 corner switches (2 pack and 2 bleed) are in AUTO or HIGH the Isolation Valve is closed.
If any of these 4 switches are OFF, the Isolation Valve is open.

Question 12

What does the DUAL BLEED light mean?

Answer 12

A DUAL BLEED light illuminates when the APU Bleed Valve is open and a possibility exists that engine bleed air could provide back pressure on the APU.
This light provides protection in the event the APU check valve should fail.
There are a number of combinations that allow a DUAL BLEED condition.

Question 13

Does the DUAL BLEED valve light look at airflow or switch position?

Answer 13

This light will illuminate whether engine #1 is running or not - since the light monitors only the position of the engine bleed switch - not the engine bleed valve.

Question 14

What is the engine limit with the DUAL BLEED light on?

Answer 14

Idle power

Question 15

Will the DUAL BLEED light will be on during normal engine starting?

Answer 15

Yes

Question 16

When do BLEED TRIP OFF lights come on?

Answer 16

Pneumatic system protection is provided by the sensors in the ductwork, when the applied bleed air temperature or pressure are too high.
A temperature sensor will close the Bleed Valve and activate the BLEED TRIP OFF light.
A Bleed Trip Off occurs to protect the pneumatic system from overtemperature conditions.
A Bleed Trip Off can also occur when excessive pressure is sensed downstream of the 9th stage bleed. The pressure sensor is located upstream of the Bleed Air Valve.

Question 17

What happens when you push the TRIP RESET button?

Answer 17

This action will reset the MASTER CAUTION lights and the AIR COND annunciator, reset the protective circuits, and restore the operation of the bleed air valve.

Question 18

What light comes on with a duct leak?

Answer 18

WING BODY OVERHEAT

Question 19

What areas are monitored for WING BODY OVERHEAT?

Answer 19

The areas monitored include the engine strut, wing leading edge, and air conditioning bays-for both left and right systems and the APU bleed air duct.

Question 20

What sensors activate the right side WING BODY OVERHEAT?

Answer 20

RIGHT LIGHT:
Right Engine Strut
Right Wing Leading Edge
Right Air Conditioning Bay

Question 21

What sensors activate the left side WING BODY OVERHEAT?

Answer 21

LEFT LIGHT:
Left Engine Strut
Left Wing Leading Edge
Left Air Conditioning Bay
Keel Beam
APU Bleed Duct

Question 22

How do you test the WING BODY OVERHEAT sys?

Answer 22

Press the OVHT TEST button.

Question 23

What is the normal air switch position for engine start?

Answer 23

Turn OFF both Pack switches before engine start so all APU air is available to start the engines.
Both Engine Bleed switches should be ON - as this is the normal position of these switches.
Each Bleed Valve remains closed until the engine is started.

Question 24

If one pack is operating on the ground, what should you consider?

Answer 24

Running it at high

Question 25

it is prohibited to use engine bleed air with the pack switch in HIGH for:

Answer 25

takeoff, approach, or landing.

Question 26

Normal air position for takeoff:

Answer 26

It is preferred to takeoff with the engines supplying the bleed air.
The Pack switches are in AUTO, the Bleed Switches are On, the APU Bleed Switch is OFF, and the Isolation Valve switch is in AUTO.

Question 27

Configuration for high performance takeoff:

Answer 27

APU bleed ON and dedicated to Left pack in AUTO.
Eng 1 bleed OFF.
Eng 2 bleed OFF.
Isolation switch CLOSE.

Question 28

After a high performance takeoff, what should you do to make sure a DUAL BLEED light doesn’t come on?

Answer 28

The APU air shutoff can be verified when the left duct pressure drops to zero.