Pneumatics Flashcards
What is bleed air used for?
- Engine starting
- Engine Cowl anti-icing
- Wing anti-icing
- Air-conditioning
- Pressurization
What are all the possible sources of bleed air?
- Engines
- APU
- External High-pressure ground air source
What is the purpose of the ACSCs?
The Air Conditioning System Controllers regulate air pressure to ensure it is supplied at an adequate pressure to satisfy pneumatic system demands
What does the Bleed air leak detection system do?
Monitors pneumatic ducting for high temperature bleed air leaks
What will happen if the bleed air leak detection system detects a leak?
It will generate a MASTER WARNING “L/R BLEED DUCT” CAS message and give an aural warning that alerts the crew to shut down the bad bleed air system.
What is the purpose of the bleed isolation valve?
Separates the right and left pneumatic systems
What position is the Bleed air Isolation Valve in normally and why?
In the Closed position in order to allow the system to be pressurized by one or both of the engines
On the bleed air panel, what does moving the bleed valves knob to the manual position do?
It allows the bleed isolation valve to be positioned manually using the “ISOL OPEN/CLSD” switch.
How is the Isolation Valve normally controlled and by what?
It is normally controlled automatically by the ACSCs
When will the ISOL OPEN/CLOSED status message display?
Whenever the bleed isolation valve is in either the fully open or closed configuration.
When will the “BLEED MISCONFIG” caution occur?
When in the manual mode and an impossible bleed configuration exists.
When the bleed valves selector knob is in manual and what does the bleed source selector knob do and what are the four options?
Allows you to change the bleed air source to one of the following:
- Both engines
- L engine
- R engine
- APU
When an engine is selected as a bleed air source, what stages from the engine does the bleed air come from?
- The LP Bleed Air - 6th stage compressor port
2. The HP Bleed Air - 10th stage compressor port
When is the HPV opened and why?
The high pressure valve is opened when the ACSC determines low pressure (6th stage) bleed air is insufficient for system requirements.
When will the HPV close?
When the LP Stage air is sufficient to satisfy system demands
What is the purpose of the check valve installed on the LP Bleed air source?
To prevent HP bleed air from flowing into the LP port
Is the HPV shown on the ECS synoptic page?
Nope
What are PRSOVs?
Pressure Regulating Shut Off Valves
What is the purpose of PRSOVs?
Regulate bleed air system manifold pressure to approximately 45 PSI.
Are the PRSOVs shown on the ECS synoptic page?
Yup
“L/R ENG BLEED” status message will be displayed when?
The respective pack inlet pressure sensor has failed
“L/R ENG BLEED” Caution message will display when?
Failure of:
- HPV
- PRSOV
- Controller
When will the “L/R ENG BLEED CLSD” status message display?
When the respective engine bleed is not selected with the HPV and PRSOV closed
How high can the APU be used as a bleed air source?
25,000’
When will the APU BLEED ON caution message display?
When the APU is selected above 25,000’ as a bleed source
What side of the Bleed Air manifold is the APU routed to?
The left side
How can the bleed air from the APU be used as a source for the entire system?
By opening the isolation valve
What is the purpose of the LCV?
The Load Control Valve allows bleed air from the APU to enter the bleed air manifold
What is the purpose of the ECU with regards to the bleed air system?
The engine control unit modulates the Load Control Valve (LCV) to limit APU exhaust gas temperature.
If the “APU LCV OPEN/CLOSED” caution message appears, what does this tell you?
The APU LCV did not move to it’s commanded position
Where is the external air connection located on the CRJ?
Located on aft left side of the fuselage below engine No. 1
For External high pressure ground air source to be used for engine starting, what should we ensure?
The bleed valves must be selected closed to avoid reverse flow to the engines. Do this by setting the BLEED VALVES selector to CLSD
What is the AILC and it’s purpose?
Anti-Ice and Leak Detection Controller, monitors pneumatic and anti-ice suction for high temperatures associated with bleed air leakage
How does the AILC sense a bleed air leak?
It uses continuous sensing loops routed in parallel (2 of them) along pneumatic ducting
What are the five zones of the AILC system?
- Left bleed
- Right bleed
- Left engine cowl
- Right engine cowl
- Wing
How many loops must detect a leak of the leak detection system before an EICAS message is displayed?
2
if both loops of leak detection system detect a leak, what will happen?
EICAS displays message indicating the faulty zone, allowing the crew to isolate the duct by closing appropriate shut-off valves
What does the DUCT MON FAULT status message indicate?
Loss of redundancy in the bleed leak detection
When will the “ANTI ICE DUCT” warning message display?
When a bleed air leak has been detected in the wing anti-ice ducting or piccolo tubes
If a “ANTI-ICE DUCT” warning message occurs, what will the AILC do?
AUTOMATICALLY select the respective system off.
When will “ANTI-ICE DUCT” caution be displayed on the CAS?
If there is a leak detected in the wing anti ice system, the AILC closes the wing anti-ice valves, BUT the crew doesn’t select the system to off.
Describe the Cowl Anti-Ice system.
Consists of an inner and outer duct, hot bleed air travels through the inner duct. The space between the inner and outer duct is monitored for pressure changes, which if a large enough one is detected, will trip the AILC to close the affected areas valves.
How are the Bleed-air leak detection system loops tested?
Automatically upon power-up
How do you know if the leak detection system loop test was successful?
There’s no message displayed if it was
If an anti-ice loop caution message appears, what happened?
Both WING anti-ice leak detection loops failed the test.
With the Bleed valves switch selected to MANUAL, where is the BLEED MANUAL text displayed?
On the ECS synoptic page and Status Page.
What is the pressure regulated to in the bleed air manifold?
45 PSI
Can you use the APU to run the Anti-Ice system?
No
If the cowl anti-ice switch is selected ON with the APU manually selected as the bleed air source, what caution message will appear and why?
BLEED MISCONFIG; because APU can’t supply adequate bleed air to handle the Anti-ice system.
What is the minimum PSI required for cross-engine bleed start?
42 PSI
Which Bleed air valves will fail-open?
COWL anti-ice shutoff valves
Where will the isolation and wing anti-ice cross bleed valves go if they fail and why?
They’ll fail where they’re at because they are electronically controlled and electronically actuated.
What are the only bleed air valves that will fail close?
All except Cowl anti-ice (fail open), isolation (fail where it’s at, electric operated), an the wing anti-ice cross bleed valve (fail where it’s at, electric operated)
Any time you’re single engine, you’re ______ pack.
Single
ANTI ICE CAUTION means what?
The wings aren’t warm enough yet.
Who does the isolation valve open during single engine operation?
To provide bleed air available to the offside pack in case we need to use it.
What prevents the cowl anti-ice valve from opening during single-engine operation?
Control system logic
Normally in flight, the whole bleed air system is _________.
On side related
AILC
Anti-Ice Leak Detection Controllers.
What do AILCs do?
Monitors temperature of the bleed air and anti ice ducting and will shut down a bleed air section that is leaking.
BLEED MISCONFIG means what?
APU manually selected, with anti-ice on.
What could happen if the WING OVHT warning is false?
The AILC will close wing anti-ice shutoff valves, message won’t go away so it closes the PRSOVs which results in no more bleed air going to the L and R PACKs
What do the packs normally supply air to?
Left Pack: Flight deck (70-85%)
Right Pack: Passenger Compartment (70-85%)
If you have a right pack deferral, what should you brief the FA on?
Don’t use the galley heater.
What do PACKS produce?
Produce cool air.
How is the AC temperature controlled and selected?
Controlled by letting more or less hot air bypass through the temperature regulating valve and selected using the AC panel.
Should we use high pressure ground air to run the packs?
No because they typically have only enough air in them for 6 engine starts.
DISPLAY COOL caution means what and what should we do about it?
Fan quit, if on ground go to GRD ALT, if in the air, go to FLT ALT.
What is the maximum altitude to select “EMER DEPRESS”?
15,000’
STBY on the display FAN knob will do what?
Turns both display fans off.
When can we use Low-pressure ground air?
Passenger door OR avionics bay door must be open.
When is the only time you would use RAM air?
If both packs are failed and not on.
The Display cooling EICAS message relays on _______ sensors
Flow sensors… not temperature
The CPAM is the primary interface with the DCU’s providing Cautions and Warnings. The static source used is provided from ________
S3
