Pneumatics - AMS Anti-Ice Systems

Question 1

What is the function of the Air Management System Controller, (the dual-channel, software based, electronic digital controller)?

Answer 1

It continuously monitors the performance of the pneumatic system components, the WHSAIS, as well as the airflow schedule of the ACS and maintains system functionality through sstem logic.

Question 2

What sub-systems are considered pneumatic?

Answer 2

Air conditioning, cabin pressurization, wing and horizontal stab anti-ice system

Question 3

How is the bleed system controlled?

Answer 3

By two bleen Pressure Regulating Shutoff Valves (PRSOV) located in each pylon

Question 4

What are the functions of the two Pressure Regulating Shutoff Valves (PRSOVs)?

Answer 4

They regulate the hot bleed air released to the ECS and AIVs and provide a firewall shutoff capability for the bleed air lines.

Question 5

What would expect regarding the AMC if the temperature were above 30c?

Answer 5

A white crew awareness EICAS message stating that one or both bleed valves has closed, which can be verified on the schematic page.

Question 6

Does a PRSOV automatically close in case of a single engine takeoff condition?

Answer 6

Yes

Question 7

Can the remaining bleed air supply all of the bleed air required by the system when in OEI condition?

Answer 7

Yes, via the cross bleed valve.

Question 8

How can the pilot override the RH PRSOV to the closed position?

Answer 8

By placing the pneumatic bleed 2 toggle switch to the OFF position.

Question 9

What does turning the ECS knob to OFF VENT do?

Answer 9

Opens the Ram Air Valve (RAV) in the rear fuselage providing fresh to both the cabin and cockpit, closes the FCSOVS and closes both PRSOVs.

Question 10

What two air conditioning modes control cockpit and cabin temperature?

Answer 10

Auto and manual modes.

Question 11

How does the crew transfer cabin temp control to the passengers?

Answer 11

By dialing the cabin temp knob full counter-clockwise into the detent.

Question 12

How is the temperature of the air to the cabin controlled?

Answer 12

Temperature modulating valves (TMVs) mix cooled air from the heat exhangers with hot bleed air based on temperature selection on the cockpit control panel.

Question 13

What is the function of the Vapor Cycle System?

Answer 13

Provides cooling air for the cabin and cockpit and is operated automatically by the ECS controller. (The VCS uses a refrigerant, evaporators, condenser and a fan to produce the cold air)

Question 14

When can the VCS be operated on the ground?

Answer 14

With GPU power, or one engine operating.

Question 15

What is used to cool the heat exchanger?

Answer 15

Ground cooling fan on the ground or ram air in flight.

Question 16

For the pressurization system to operate automatically, what input is required by the flight crew priort to departure?

Answer 16

Landing field elevation (LFE) must be set.

Question 17

What is the purpose of the dump button?

Answer 17

Provides cabin depressurization by opening the outflow valve. If pressed a second time, the system returns to normal. It also turns off the recirculation fans.

Question 18

Where is the outflow valve located?

Answer 18

It is mounted on the aft pressure bulkhead

Question 19

What is the purpose of the negative and postive relief valves?

Answer 19

They are designed to prevent over or under pressurization of the fuselage; the are not actuated during normal operation.

Question 20

Which subsystems do the ice and rain protection include?

Answer 20

Wings, horizontal stab, engine air intakes, pitot and static, and windshields

Question 21

What heats the engine nacelle intake?

Answer 21

Engine bleed air.

Question 22

With the loss of electrical power, what is the default position of the engine anti-ice valves?

Answer 22

Open, providing continuous bleed air to the engine inlet

Question 23

What does an “A-I E 1/2 FAIL” indicate?

Answer 23

Loss of anti-ice protection to that engine; must avoid icing conditions

Question 24

How are the wings and horizontal stab heated?

Answer 24

Each side is heated using bleed air from the respective sie engine; if one bleed source fails, the entire system is heated from the remaining source. (The pneumatic system supplies bleed air at controlled temperature and pressure to the WHSAIS, using controlled ot pleed air from the engine compressors. The hot air is then delivered to piccolo tubes for heating the wings and stab.)

Question 25

In order to deal with engine bleed flow limitations, how is the WHSAIS operation limited?

Answer 25

By a WHSAIS envelope. (Temperature and altitude are the two variables that determine the envelope’s parameters. If the aircraft is flying inside the envelope and the wingstab switch is ON, the FADEC increses the engine idle levels to provide the minimum engine bleed pressure and temperature for proper operation.)

Question 26

What does “A-I WINGSTB INHB” CAS message indicate?

Answer 26

WHSAIS switched ON outside the icing envelope. Or, aircraft is in single bleed configuration and above 15,000 ft. Icing envelope when WHSAIS is switched on.

Question 27

At what altitude is the WHSAIS operation limited to in a single-bleed source scenario?

Answer 27

15,000 ft