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