Air Management System Flashcards
What does the Air Management System consist of?
Pneumatics (air to be used), Environmental Control System (ECS, regulates and distributes air), Pressurization (maintains a safe cabin altitude)
What sources does the pneumatics get air from?
Engines, APU, External Air Source
What are pneumatics used for?
ECS, Engine Start, Pressurization, Anti-ice, Water Pressure
Where does pneumatic (bleed air) come from in the engine?
6th (Low) and 10th (High) stages of the COMPRESSOR
How is engine bleed air cooled?
There is a pre-cooler for incoming air to the pneumatic system.
What is engine bleed air used for?
ECS, Anti-Ics, Water Pressure, Pressurization, Engine Start
What is APU bleed air used for?
ECS, Water Pressure, Pressurization, Engine Start
What air the external air sources available for the pneumatic system?
Air conditioning cart can be used to cool the aircraft’s cabin, high pressure air start cart or air bottle? can be used to start an aircraft’s engine
When starting the engines with the air start unit, what is important to remember?
Both PACKs need to be turned OFF when starting with an external air source to prevent air contamination to the cockpit and cabin
What is the Environmental Control System (part of the AMS) composed of?
2 packs, recirculation fans, pre-cooler, grasper ventilation, electronic compartment ventilation, cargo bays ventilation, emergency ram air ventilation
Where are the packs for the ECS located?
one located in each wing to fuselage fairing (fwd)
What provides air for pack 1 and 2?
Engine 1 for pack 1, engine 2 for pack 2
How is pack air temperature controlled as it leaves the pack?
Set via temperature control knobs in the cockpit, cabin fwd panel
Can a single pack provide air for the entire ECS? Are there any limitations?
Yes, to a maximum altitude of FL310
What is the purpose of the recirculation fans?
Help reduce the load on the packs by recirculating already-conditioned air and remixing it with incoming cabin/cockpit air
When the recirculation fans mix air, what is the percentage of fresh to recirculated air?
52% fresh air, 48% recirculated air
In what situations will the recirculation fans not work?
When the DUMP button is pressed, Smoke is detected in the recirculation bay, or when the respective pack is OFF, when APU is bleed priority
What provides personal air to each pilot and passenger?
Gasper Ventilation
Which recirculation fan supplies air to Gasper Ventilation to passengers?
The right recirculation fan
Which electronics compartments are ventilated and how?
Fwd, central and aft with conditioned air from the cabin and expelled overboard
How are the cargo bays ventilated?
The aft cargo bay is not vented. The fwd cargo bay receives air from the cabin which is then vented overboard
What if both packs fail?
Emergency Ram Air Ventilation allows ventilation in case of failure of both packs
How does the emergency ram air ventilation work?
Enters the left side of the system through a valve if: in flight and both packs are OFF/failed AND below FL250; Enters the right side of the system through a check valve that opens when: outside pressure is greater than inside pressure
What is the purpose of the pre-cooler?
Uses ram air to cool the bleed air ~204deg C coming from the engines going to the ECS
What is the pressurization system composed of?
Cabin Pressure Control System (CPCS) which is comprised of: Cabin Pressurization Controller (CPC), Outflow Valve (OFV), Negative Pressure Relief Valve (NPRV), Positive Pressure Relief Valve (Safety Valve), and Static Port
What is the purpose of the pressurization system CPC Cabin Pressurization Controller?
Controls the OFV Out Flow Valve, 2 Channels that alternate each flight
What is the purpose of the OFV in the pressurization system?
Regulates the amount of air leaving to maintain aircraft pressurization
What are the functions of the pressurization mode switch?
AUTO - pressurization is controlled by the CPC Cabin Pressure Controller, MAN - pilot requests desired position of OFV, LFE - allows manual input of landing field elevation while still operating in the AUTO mode
What is the purpose of the NPRV Negative Pressure Relief Valve? Is there a NPRV limitation?
Opens automatically when outside (ambient) air pressure is greater than cabin pressure; limitation: -.5 psi
What is the purpose of the PPRV Positive Pressure Relief Valve?
(Safety Valve) opens when cabin pressure reaches 8.6 psi (OFV failure) to prevent 8.8 overpressure limit
What is the purpose of the static port?
Senses and transmits environmental static pressure to the Positive Pressure Relief Valve
What is the purpose of the DUMP button?
Only works in AUTO mode, shuts OFF packs and recirculation fans, allows cabin to climb to a max altitude of 12,400 feet at 2,000fpm
What does the AMS use bleed air for?
ECS (heating and cooling), engine start, pressurization, engine and wing anti-ice, water pressure, hot air leak detection
How many AMS controllers are installed?
One controller with 2 channels which control the respective onside systems
What happens if an controller channel fails?
The remaining channel is able to control the entire AMS
What provides bleed air for the AMS?
Engine bleeds, APU bleed, External Pneumatic Source
What is bleed air used for?
ECS, engine start, engine and wing anti-ice, water pressurization
What is external pneumatic air used for?
ECS on the ground, engine start on the ground
Where is the external ground source panel located?
Lower fairing between the wings
What is the primary use for APU bleed air?
ECS on the ground, engine starting on the ground, electrical source at or below FL330, assist with engine start at or below FL210, bleed source for pressurization, heating and cooling at or below 15,000’
Can engine bleed air flow back to the APU?
No. A check valve prevents flow back
Where is bleed air tapped from the engine?
6th (low) and 10th (high) compressors (EVB and HSV respectively), system alternates between valves to regulate an adequate and safe pressure
What is the normal pressure for any engine operation?
45 psi
What is the purpose of the pre-cooler?
Cools the bleed air coming from the engine to the AMS
What cools the pre-cooler?
Ground N1 fan, flight N1 fan or ram air FAMV fan air motor valve
What does the Overheat Detection System (ODS) observe?
Engine bleeds and packs, APU bleed, plumbing for the wing and engine anti-icing system
Do both ODS loops have to function in order to detect an overheat condition?
Yes, but if one fails the other will work alone to detect the overheat
How many ECS packs are on the airplane? What provides air for the packs?
2 independent packs (pack 1 and 2), each engine provides bleed air to its respective pack
Can a single pack provide adequate temperature control and pressurization?
Yes, up to FL310
Can a single bleed source power both packs?
Yes, through the crossfeed valve
What is the ratio of fresh air to recirculated air?
52% fresh, 48% recirculated
When are the recirculation fans commanded off?
Cockpit switch OFF, smoke detected in the recirculation bay, DUMP button is pressed, respective pack is commanded off
What keeps the 3 avionics E-Bays cool?
FWD and CTR E-Bays use 3 fans to pull cabin air into the E-Bay, AFT E-Bay uses natural air-flow from the cabin to the bay
When is the Emergency Ram Air Ventilation activated?
When both packs are commanded or failed OFF below 25,000’ (via left side and electronically controlled, SOV) or when ram air pressure is greater than cabin pressure (via right side, check valve)
How many channels are on the CPC Cabin Pressure Control?
2 channels, one active and one in standby
Where does the CPC Cabin Pressure Control get LFE Landing Field Elevation?
FMS or can be manually selected by the LFE knob
What happens when the DUMP button is pressed?
Commands both ECS packs OFF, Opens OFV and raises the cabin to 12,400’ at a rate of 2,000fpm
Can the cabin altitude be raised higher than 12,400’?
Yes, by using manual mode, cabin altitude will rise due to a natural leak
In manual mode will the cabin depressurize on landing?
No
What is the bleed system priority in flight?
Onside engine, opposite engine, APU if available
If engine and APU bleed air are available simultaneously on the ground, which has priority?
APU has priority if: aircraft is on the ground, wheel speed is less than 50kts, or opposite engine bleed pressure is not enough for engine start, APU bleed is OFF
When will the cross bleed valve open automatically?
Anytime manifold pressure is on one side but there is not a bleed source on the other side:
- On the ground main engine start APU bleed OFF
- Engine 2 start in the air
- Engine 1 start in the air IF APU is not available
What are some things that will close the ECS packs?
- Any engine start if APU is the bleed source
- engine start on the ground
- respective bleed system duct leak
- bleed air source not available for the pack
- TL set to MAX on takeoff and APU OFF
- REF A/I set to ALL on takeoff and APU OFF
- REF ECS set to OFF on MCDU (APU is OFF)
one engine inop and bleed is not available up to 9,700’
see Sys Manual
When are ECS packs recovered?
TL not at MAX, and: airplane is 500 AFE with both engines operating or airplane is above 9,700’ MSL with one engine operating
What happens if smoke is detected in the recirculation bay?
Both recirculation fans deactivate, cargo recirculation fan deactivates, and cargo OFV closes
Where does the CPCS get cruise FL and LFE from?
FMS before takeoff or CPCS calculated using ambient pressure, LFE may be manually inputted
What color is the LFE on the EICAS?
Green FMS input, Cyan Manual input (an “M” will be in front of the LFE)
What is the ABORT mode?
Cabin is scheduled back to the takeoff altitude IF: airplane stops climbing and starts a descent AND airplane has not climbed above 5,000’ AFE or above 10,000’
What does the cabin up/down switch do?
the up opens the OFV, raising cabin pressure. down closes the ofv, decreasing cabin pressure
When should the hot weather checklist be used?
Above 30deg C or 86deg F
Pushing the dump switch on the pressurization panel in the cockpit will
depressurize the cabin to a maximum of 12,400’ cabin altitude, and deactivates the recirculation fans and the ECS packs
Cabin zone temperature control
can be transferred from the cockpit control panel to the flight attendant control panel
The warning message CABIN ALT HI together with a red cabin altitude indication will be displayed whenever the cabin altitude exceeds
9,700’
The CPCS cabin pressure control system consists of the following components
cabin pressure controller, cabin outflow valve, negative relief valve, positive pressure relief valve, static port
During cruise below FL370, the nominal differential pressure is limited to
7.8 PSI
Which of the following components regulate the air flow into the ECS packs?
The flow control valve
The CPCS calculates a target cabin altitude for each of the following CPCS flight modes:
ground, taxi, takeoff, climb, cruise, descent, and abort
The positive pressure relief valve (safety valve) opens independently whenever the differential pressure exceeds
8.6 PSI
The emergency ram air valve is commanded open when
if Pack 1 and Pack 2 are commanded/failed OFF and the altitude is less than FL250
Where is the AMS Controller located and what does it provide? (The Pressurization system has a separate controller the CPCS)
SPDA 2
Bleed Control Environmental Control Hot Air Leak Detection Crex Oxygen Monitoring Wing and Anti-Ice Protection
What are the pneumatic system sources?
Engine Bleed Air, APU Bleed Air, or External Pneumatic Source (Air Start Cart OR AC low pressure tube)
What 4 systems is bleed air provided to?
The engine starter, the anti-ice system, the ECS, and for water pressurization.
How are the various changes in engine temperature and pressure output regulated in the pneumatic system?
Bleed air is taken from LP at stage 6 via a check valve or HP at stage 10 to help regulate temperature. Stage 10 is used during low engine power settings and stage 6 is used when the engine is at high power settings. THEN the precooler regulates the temperature further. Pressure and temperature sensors are past the precooler
How does the pneumatic system precooler function?
It cools the pneumatic air to a predetermined value by fan air on the ground or in flight by ram air or fan air. The AMS controller automatically controls bleed air.
What happens when the Bleed buttons are pushed?
A white bar illuminates and the bleed valves are closed
What is the primary purpose for APU pneumatics?
Primarily for the ECS on the ground or for engine start, although it may be used for ECS in flight as well.
What prevents engine bleed air from flowing to the APU while the engines are running?
A check valve
What stops the APU bleed air from connecting to the pneumatic system?
The APU bleed button closes the APU bleed air valve (separate from the check valve) as commanded by the APU FADEC
Where is the air start cart connection located?
With the AC Cart connection under the fuselage.
What monitors the pneumatic system for dangerous hot air leaks?
The overheat detection system uses sensor loops to send a signal to the AMS controller if there is a leak. And the bleed system is shut down according to system logic (leak on side 1, side 1 bleed off) AN AMBER BAR ILLUMINATES ON THE BLEED BUTTON
What are the 2 lights for on the bleed buttons?
The lower light is white for bleed air valve manually closed, and the upper light is amber for a bleed air leak detected.
How many pneumatic networks are there?
2 individual pneumatic networks
If more than 1 bleed air source is available, what is the bleed air logic priority?
Onside engine, opposite engine, APU if activated (except for the anti ice system operation in flight)
If a bleed air source, like the engine, fails, how is bleed air transferred from one side to the other?
Via the crossbleed valve, which is normal for engine start operation.
In what conditions will the ECS PACK 1 or 2 close?
A bleed air source is not available, the pack button is off, any engine is starting, any engine is starting and APU is the bleed source, bleed system duct leak, BIT failure shutdown
When are the ECS packs recovered if the thrust levers are not set to MAX?
when any of the following occur:
TLA reduction
500’ AFE with 2 engines operating
Flight above 9,700’, for takeoffs at or below 8,000’ and SE
The airplane is above 15,000’ for takeoff fields above 8,000’ and or SE
The airplane is above 9,700’ during GA, if SE
What does the AMS auto logic control?
Engine Bleed, APU Bleed, ECS packs, recirculation bay smoke detection
When is the EBV Engine Bleed Valve commanded to Open? How about the APU bleed valve?
Bleed valve switch is in auto, engine bleed is available, no fire is detected in the engine, no bleed duct leak is detected
Same for APU except Left engine bleed is not available, anti-ice system not requested, or A/I system requested ON and A/I system is failed
When the APU and Engines bleeds are both available, when will the APU be prioritized?
When all of the following are met:
- Opposite engine bleed is below the min for engine start
- WOW
- GS < 50kts
- Altitude < 15,000’
- APU bleed is avail and wing A/I is not requested
- The crossbleed valve is operating normally
When is the crossbleed valve commanded open automatically?
- One side provides manifold pressure and there is not a bleed source on the opposite side
- APU bleed button is pushed out for main engine start
- Engine #2 start in the air
- APU bleed OFF for engine #1 start in the air
- No bleed leak, unless starting an engine
What situations will close Packs 1 and 2?
- Bleed air not available
- Pack switch is OFF
- Engine is starting and WOW
- Engins is starting and APU is the bleed source
- Respective bleed system duct leak
- Pack BIT senses a failure (PACK 1 FAIL)
- ECS OFF on MCDU according to system logic
- The respective engine is starting, no WOW, opposite engine is not starting
How does FADEC system logic turn off the ECS packs?
The ECS OFF signal is sent from the engine FADEC to the AMS controller (in the SPDA), depending on the:
- TDS input (REF ECS OFF)
- Pressure alt
- Flight Phase
- Engine Inoperative Detection
When will the AMS controller disregard the FADEC signal to turn the ECS packs off?
Above 15,000’
What operating conditions close the Packs automatically? What conditions automatically recover the packs?
- SE and APU bleed not available
- TLA set to MAX and APU bleed not available
- TDS REF ECS OFF and APU bleed not available
- TDS REF ECS OFF and TDS REF A/I ALL
The packs are recovered if:
- TLA below TO/GA
- 500’ AFE on takeoff
- Flying above 9,700’ for takeoff at fields 8,000’ or below AND SE
- Flying above 15,000’ for takeoff at fields above 8,000’ AND SE
- Flying above 9,700’ during GA AND SE
What happens if smoke is detected in the recirculation bay?
The recirculation bay smoke detector will command the recirculation fans off.
What does the ECS system provide air to?
- AC for cockpit and cabin
- AC for gaspers
- Filtered air recirculation
- Fan air cooling for avionics bays
What is the purpose of the ECS emergency ram air ventillation system?
For cockpit smoke removal
Where are the packs located?
The wing to fuselage fairing
How does the AMS control the quantity of air provided to the pack?
Before each pack in the pneumatic system there is a pack flow control valve FCV.
What provides bleed air to pack 1 and 2 during normal operations?
Engine 1 and 2 respectively
How can 1 engine provide pneumatic air to both packs?
Via the crossbleed valve
Where do the recirculation fans get the air it sends to the cabin from?
The recirculation bay and sends it back through the mixer to the gaspers.
What does the RECIRC button control?
Recirculation bay fans. Pushed in is AUTO, pushed out is OFF
When will the recirculation fans turn off?
Dump button, smoke detected in the recirculation bay, turned off via the RECIRC button
Do the pilots have Gaspers?
Yes
How are the Gaspers normally fed?
Via the pack air from the mixer
How are the gaspers fed if the gasper air supply exceeds 35deg C (95deg F) to keep passengers from being fed hot air?
The gasper SOV automatically opens and air from the right recirculation fan now supplies air to the mixer. In normal operation, the gasper SOV is closed.
How is the forward e-bay ventilated? How many fans are there?
The forward e-bay is provided with forced cooled air from 3 fans that pull air from the cockpit area and expell the heated air to the recirculation bay. A flow sensor monitors fan/flow monitoring.
How is the center e-bay ventilated? How many fans are there?
3 fans provide forced cooling air to the center e-bay from the rear cabin return area of the recirculation bay and expell the hot air towards the lower forward recirculation bay area. Flow sensors are used for fan/flow monitoring.
How is the aft e-bay ventilated? How many fans are there?
Air flows naturally from the passenger cabin to the aft e-bay and is expelled towards the underfloor recirculation bay. There are no fans.
Where does the fwd cargo bay fan get air from to cool animals? Where does it leave the bay?
Fan air enters the back of the fwd cargo compartment via the recirculation bay and is expelled via the SOV which brings air back to the recirculation bay when open.
When is the Pack 1 emergency ram air (SOV) valve commanded open?
Airplane in flight, pack one and 2 are OFF or failed, and below FL250
When is the Pack 2 emergency ram air check valve commanded open? Does it use electricity like the Pack 1 emergency ram air SOV?
It does not use electricity it is mechanical. The check valve opens whenever the pressure in the ram air ducting is greater than cabin pressure.
What regulates the cockpit and pax cabin temperature once the dials are moved? Can the fwd and aft pax cabins be controlled separately?
The AMS controller
The fwd pax cabin can be controlled separately from the aft pax cabin via separate temperature dials on the FA control panels. There are 3 indications on the EICAS synoptic page: ckpt, fwd cab, aft cab
How do you know what temperature you are selecting when you turn the temperature dial?
Look at the ECS synoptic page. The set temperature is on the left in blue while the actual is to the right in green.
Where is the static port for the PPRV located?
On the left, aft fuselage
What does LFE stand for?
Landing field elevation
What does the cabin alt switch do?
Controlls the OFV manually
What information inputs does the CPCS use to set the reference cabin pressure?
Ambient pressure, engine power signals, landing gear information, barocorrection, landing field elevation LFE, and cruise flight level
What happens to the Cabin pressure controller channels while in manual mode?
Both channels become standby so the cabin alt switch position can be controlled by the pilots. One channel will still be used to change the OFV when the manual switch is used.
What are the limits to consider while operating in manual pressurization mode?
Manual mode IS differential pressure limited
Manual mode IS NOT cabin altitude limited and no automatic cabin depressurization on ground is provided
When does the PPRV open?
8.6PSI or more
What limits the negative differential pressure?
The negative pressure relief valve uses springs to limit the negate differential pressure to -.5PSI (for example, if you were landing at an airport below MSL)
Is the PPRV (safety valve) heated?
Yes. To ensure there is no ice accetion.
What happens when the LFE CTRL mode switch is used?
The CPC remains in AUTO mode, but allows the pilot to override the LFE landing field elevation. The LFE selector knob can then be used to set the LFE (perhaps the airport is not in the MCDU so the LFE must be manually set)
What is the purpose of the DUMP button?
For emergency smoke removal or emergency evacuation
When will LFE automatically return to takeoff field elevation?
If the present pressure altitude is below 10,000’ or 5,000’AFE
What is the nominal differential pressure limited to below FL370? Above FL340 to FL410? What is the max cabin pressure altitude?
7.8PSI below FL370 (system limits it but it is not a limitation)
8.4PSI FL370 - FL410
As a result, maximum cabin pressure altitude is 8,000’
When is the CABIN ALTITUDE HI warning activated?
Whenever the cabin pressure altitude rises above 9,700’
OR if taking off from an airport above 8,000’, it will activate for cabin altitudes 500’ AFE
What happens if the cabin altitude exceeds 14,500’?
The cabin outflow valve will close automatically to prevent the cabin from climbing further.
Can the cabin altitude rise above 12,400’ after pressing the DUMP button?
Yes. Due to natural leak as the OFV will be closed.
Can the cabin be depressurized to a cabin altitude above 12,400’ by the pilot instead of by natural leak?
Yes. The pilot can switch to manual mode
What happens if the DUMP button is pressed twice?
The system returns to normal operation.
How can you tell the OFV positon?
Look on the ECS synoptic page
How do pilots find the proper cabin altitude to select?
In the flight manuals
Can the FWD cargo compartment temperature be controlled?
No dedicated temperature control is available for cargo compartments.
The air flowing from passenger cabin heats the FWD cargo compartment, providing proper conditions for live animals carriage.
ABV
Auxilliary Power Unit (APU) Bleed Valve
EBV
Engine Bleed Valve
FAMV
Fan Air Motor Valve
FCV
Flow Control Valve
HPSOV
High Pressure SOV
OBV
Operability Bleed Valve
PRV
Pressure Regulating Valve
RAID
Ram Air Inlet Door
