CRJ-200 ECS and Pneumatics

Question 0

What is 10th stage bleed air used for?

Answer 0

It is used for engine starting, packs for cooling and jet pump for outflow valve operation.

Question 1

What is the source of bleed air for the ECS and Pneumatics?

Answer 1

Bleed air is taken from the 10th and 14th stages to supply the ECS and Pneumatics with required air.

Question 2

Beyond the engines where else can 10th stage bleed air be supplied?

Answer 2

It can also be supplied by the APU and a high pressure air cart.

Question 3

What controls the 10th stage SOVs and how do they operate?

Answer 3

They are controlled by switch lights on the ECSCP. They are electo-pneumatic, which means that both electricity and pneumatics must be present to operate. They will fail closed if either is missing.

Question 4

What protects the APU from attempting to providing to the same duct work as an engine?

Answer 4

The interlock feature is based off of switch position only and will not allow the APU LCV to open regardless of engine operation if either engines 10th stage bleed air is selected.

Question 5

What valves will automatically open and close during engine start?

Answer 5

The L and R 10th stage valves, the isolation valve and the respective engines ATS will all open. The pack PRSOVs will both close during engine start.

Question 6

Why is there a limitation of 70% N2 on the operating engine during a start with the APU operating?

Answer 6

Since the LCV will not close the APU is suseptible to being back flushed by the operating engine should it’s bleed source provide too much pressure.

Question 7

What does the 14th stage bleed air do?

Answer 7

The 14th stage bleed air is utilized for wing and cowl anti-ice as well as thrust reverser deployment.

Question 8

What controls the 14th stage SOVs and how do they operate?

Answer 8

They are controlled by switch lights on the ECSCP. They are electo-pneumatic, which means that both electricity and pneumatics must be present to operate. They will fail open if either is missing. Thus ensuring adequate anti-ice is provided.

Question 9

What does BLEED MISCONFIG Caution mean and why do we get it?

Answer 9

It represents that the engine bleeds are being used to supply both ECS and anti-ice operations at the same time with the gear down or flaps extended beyond zero. Since utilizing both bleed air sources dramatically reduces engine thrust this is prohibited in critical phases of flight.

Question 10

What are the components of the ECS?

Answer 10

Packs, Display and Avionics Cooling, Cargo Bay cooling, Pressurization

Question 11

What are the components of the Pneumatics?

Answer 11

10th and 14th Stage and Bleed leak detection

Question 12

How are the bleed switches controlled and how do they fail?

Answer 12

The bleed valves are controlled by electro pneumatic switch lights that fail in the closed position.

Question 13

What is the interlock protection feature?

Answer 13

The interlock prevents the APU LCV from opening regardless of actual valve position if either the L or R and Isol Valves are selected open. It is based entirely off of switch light selection.

Question 14

What is the purpose of the interlock protection?

Answer 14

It prevents APU back flush from engine bleed air.

Question 15

What is the maximum N2% during APU engine start?

Answer 15

70% N2

Question 16

How are bleed leaks detected?

Answer 16

The outer casing surounding the bleed lines fill with the hot air. This air is exhausted in predrilled holes located adjacent to heat detector loop(s) which generate the warning.

Question 17

What areas are protected by dual loops?

Answer 17

The 10th stage area between the pack, SOV and ISOL valve is protected by dual loop protection.

Question 18

What areas are protected by single loop?

Answer 18

The 14th stage is protected by a single loop between the SOV and the wing SOV.

Question 19

Where are the air conditioning packs located?

Answer 19

The aft equipment bay.

Question 20

What does the pack switch light control?

Answer 20

The pack switch light controls the associated PRSOV allowing bleed air into the pack.

Question 21

Where does pack precooler exhaust air?

Answer 21

On the rear left side of the fuselage.

Question 22

What does the manual increase/decrease switch control?

Answer 22

The dual bypass valve controls the amount of air going through the heat exchangers and through the hot air bypass.

Question 23

Why is operation of the packs below 3 C not allowed while in manual mode?

Answer 23

As the ice resulting from the negative temperatures builds in the water seperator which can lead to damage and cycling out of the pack.

Question 24

Where is the cabin temperature sensor located?

Answer 24

Under the overhead bin in row 8.

Question 25

What is the source of the air used to cool the bleed air in the packs?

Answer 25

Ram air enters the top of the fuselage in the APU door.

Question 26

What are the causes of PACK FAULTs?

Answer 26

Either high temp or high pressure causes a pack fault.

Question 27

What happens when there is a pack fault?

Answer 27

A caution message with the associated pack switch light illuminating are the visual indicators. The associated pack PRSOV will automatically close. If the engine is the source of the bleed air the engine 10th SOV and isolation valve close automatically.

Question 28

What is the purpose of ram air in normal operations?

Answer 28

Ram air is normally used for heat exchangers and hydraulic cooling.

Question 29

What is the purpose of the dual position valve in the left pack plumbing?

Answer 29

The butterfly switch is electrically controlled valve that modulates in order to keep equal pressurization between the flight deck and the cabin.

Question 30

Where is air from the distribution manifold routed?

Answer 30

The conditioned air leaves the distribution manifold and is introduced through the gasper vents and dado floor panels.

Question 31

What type of air is utilized in flight to cool the avionics and displays?

Answer 31

Reconditioned air from the flight deck passes through a filter and cools the displays.

Question 32

When is conditioned air utilized for avionics and display cooling?

Answer 32

On the ground.

Question 33

Where does the standby fan draw air from to cool the avionics and the displays?

Answer 33

It uses unfiltered air pulled through the fan to cool.

Question 34

How many ARINC fans are there and where do they draw there air for cooling the ARINC racks?

Answer 34

There are two fans associated with ARINC rack cooling. They draw air from cabin exhaust under the floor to cool the racks.

Question 35

Where is the air exhausted from the ARINC racks and the CRT displays?

Answer 35

When the main cabin or service door is open the air is exhausted overboard. After the doors are closed it is vented in the aft fuselage near the outflow valves.

Question 36

What happens when the cargo fan switch is selected to off?

Answer 36

The recirculation, exhaust and conditioned air SOVs are closed. The fan and heater are deactivated as well.

Question 37

What happens when the cargo fan switch is selected to fan?

Answer 37

The conditioned air SOV is closed and the fan is heater is deactivated.

Question 38

Where does the cargo bay recieve it's conditioned air?

Answer 38

The air is distributed from the right pack distribution manifold to the cargo bay.

Question 39

What happens when either of the cargo bay smoke detectors detect smoke?

Answer 39

The exhaust, conditioned air and recirculation SOVs all close and the heater are both deactivated.

Question 40

What controls the pressurization of the aircraft?

Answer 40

There are two electro pneumatic outflow valves that control the pressurization.

Question 41

What is the maximum pressure differential for the aircraft?

Answer 41

8.7 psi

Question 42

What is the maximum negative pressure differential?

Answer 42

-0.5 psi

Question 43

What is the the altitude limiter on the outflow valve?

Answer 43

The altitude limiter provides protection to stop cabin altitude at 14,250' +/-750'

Question 44

Do the pressure differentials and altitude limiter require power or pneumatics?

Answer 44

They require neither, these are built directly into the outflow valves.

Question 45

What normally controls the outflow valves?

Answer 45

The Cabin Pressure Controllers (CPCs) normally control the outflow vavles via an electric tourqe motor that controls the required vacuum.

Question 46

What is used to control the outflow valves?

Answer 46

10th stage air passes through a venturi jet pump that provides the necessary vacuum to open the valves.

Question 47

How many CPCs are on the aircraft?

Answer 47

There are two CPCs, CPC 1 is the primary and CPC 2 is the secondary.

Question 48

How is it decided which CPC is active?

Answer 48

The CPC is switched from one to the other if one fails or 3 min after each landing. Although only one is active at any given time they control both outflow valves since they are interconnected.

Question 49

How many pressurization modes are there and what are they?

Answer 49

8; Ground - W on W, outflows are commanded to full open; Prepressure - W on W and thrust levers advanced, cabin pressurizes to -150' AGL @ 300 fpm; Takeoff abort - Cabin climbs at 500 fpm for 20 s then outflow valves are commanded to full open; Climb - W of W in climb, the cabin climbs at 500 fpm to the selected landing pressure or scheduled cabin pressure; Descent - cabin descends to the selected landing pressure -150' or the normal P; Landing - cabin climbs at 500 fpm for 60 seconds then outflow valves fully open; Touch and go - If the levers are advanced after activation of landing then the a/c will go to prepressure mode; Flight Abort - if the a/c has not reached 6000' AFE and begins a descent of 1000'/min within 10 minutes of departure the cabin will return to the departure airport elevation

Question 50

What situation would be required to have a Press Cont Fault on the switchlight?

Answer 50

The failure of both CPCs would result in a fault light on the Press Cont switchlight, it would also be noted by the AUTO PRESS caution.

Question 51

At what rate and to what altitude will the CPCs take the cabin by depressing the EMER DEPRESS switchlight?

Answer 51

~5000 fpm to 14,250' +/-750'

Question 52

What monitors the cabin pressurization?

Answer 52

The Cabin Pressure Acquisition Module, CPAM monitors the cabin altitude and pressure differential. It will display resulting EICAS messages along with seatbelt and no smoking signs in auto above 10,000'.