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What does the AMS use bleed air for?
- • ECS (heating & cooling)
- • Engine start• Pressurization
- • Engine and wing anti-ice
- • Water pressure
- • Hot air leak detection
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How many AMS controllers are installed?
One controller with 2 channels which control the respective onside system
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What happens if a channel fails?
The remaining channel is able to control the entire AMS
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What provides air for the AMS?
• Engine bleeds
• APU bleed
• External Pneumatic Source
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What is bleed air used for?
• ECS (heating & cooling)
• Engine start
• Engine and wing anti-icing
• Water pressurization
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What is external pneumatic air used for?
• ECS on the ground
• Engine start on the ground
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Where is the external ground source panel located?
Lower fairing between the wings
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What is the primary use for APU bleed air?
- • ECS on the ground
- • Engine starting on the ground
- • Electrical source (< FL330)
- • Assist with engine start (< FL210)
- • Bleed source for pressurization, heating, and cooling (< 15,000 ft MSL)
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Can engine bleed air flow-back to the APU?
No. A check valve prevents flow-back
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Where is bleed air tapped from the engines?
• 6th and 10th stage compressors (EBV and HSV respectively)
• System alternates between valves to regulate an adequate and safe pressure
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What is normal pressure for any engine operation?
45 psi
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What is the purpose of the pre-cooler?
Cools the bleed air coming from the engine to the AMS
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What cools the pre-cooler?
• Ground N1 fan
• Flight N1 fan or ram air
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What does the Overheat Detection System (ODS) observe?
• Engine bleeds and packs
• APU bleed
• Plumbing for the wing and engine anti-icing system
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Do both loops have to function in order to detect on overheat condition?
Yes, but if one fails the other will work alone to detect the overheat
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How many ECS packs are on the airplane? What provides air for the packs?
• 2 independent packs (left and right)
• Each engine provides bleed air to it’s respective pack
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Can a single pack provide adequate temperature control and pressurization?
Yes, up to FL310
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Can a single bleed source power both packs?
Yes, through the crossbleed valve
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What is the ratio of fresh air to recirculated air?
52% fresh air to 48% recirculated air
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When are the recirculation fans commanded off?
- • Cockpit switch
- • Smoke detected in the recirc bay
- • DUMP button is pressed
- • Respective pack is commanded off
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What keeps the 3 avionic E-BAYs cool?
• FWD & CTR E-BAY 3 fans each pull air from cabin to bay
• AFT E-BAY Natural air-flow from cabin to bay
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When is the Emergency Ram Air Ventilation activated?
• Both packs commanded or failed OFF below 25,000 ft (via left side and electronically controlled)
• Ram air pressure greater than cabin pressure (via right side)
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How many channels on the Cabin Pressure Control (CPC)?
2 channels, one active and one in standby mode
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Where does the CPC get Landing Field Elevation (LFE)?
FMS or can be manually selected
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What happens when the dump button is pressed?
• Commands both ECS packs OFF
• Opens OFV and raises the cabin to 12,400 ft at a rate of 2,000 fpm
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Can the cabin altitude be raised higher than 12,400 ft?
• Yes, by using manual mode
• Cabin altitude will rise due to natural leak
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In manual mode will the cabin depressurize on landing?
no
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What is the bleed system priority in flight?
• Onside engine
• Opposite side engine
• APU (if available)
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If engine and APU bleed air are available simultaneously, which has priority?
• APU has priority if
- ? Aircraft is on the ground
- ? Wheel speed < 50 kts
- ? Opposite engine bleed pressure is not enough for engine start
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When will the crossbleed valve automatically open?
• Only one side bleed source is available
• Engine 2 start in the air
• Engine 1 start in the air if APU is not available
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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
- • REF A/I set to ALL on takeoff
- • REF ECS set to OFF on MCDU (APU is OFF)
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When are ECS packs recovered?
• TL not at MAX, and
- ? Airplane is 500 AFE with both engines operating
- ? Airplane is > 9,700 MSL with one engine operating
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What happens if smoke is detected in the recirculation bay?
- • Both recirc fans deactivate
- • Cargo recirc fan deactivates
- • Cargo outflow valve closes
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Where does the CPCS get cruise flight level & landing elevation from?
• FMS before takeoff or CPCS calculates using ambient pressure
• LFE may be manually inputted
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What color is the LFE on the EICAS?
• Green FMS input
• Cyan Manual input (an ‘M’ will be in front of LFE)
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What is the ABORT mode?
• Cabin is scheduled back to the takeoff altitude if
- ? Airplane stops climbing and begins a descent, and
- ? Airplane has not climbed > 5,000 AFE or > 10,000 MSL
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