What are the primary functions of the Bleed Air System?
- (ECS) - Transfer bleed air from the low & high pressure ports to individual system requiring bleed air;
- (Pressurisation) - Control bleed air Pressure;
- (A/C) - Supply and control Temperature of bleed air to the Air Conditioning System;
- (Engine Start) - Supply bleed air for Engine Starting;
- (A/I) - Supply bleed air for the Wing and Cowl Anti-Ice Systems;
- (APS) - Supply and control Temperature and Pressure of bleed air to the APS (Air Preparation System).
What is both the Normal and Maximum Positive relief Differential Pressure?
- Normal: 10.30 psi at FL510;
- Maximum: 10.73 psi.
What is the Maximum Negative relief Differential Pressure?
Minus - 0.5 psi.
What is the Maximum Differential Pressure during Taxi & Takeoff?
+0.1 psi.
What is the Maximum Differential Pressure upon Landing?
+1.0 psi.
Above which altitude is AUX PRESS prohibited?
AUX PRESS prohibited above 41,000 ft.
How is the Landing Elevation set during QFE operations?
- Must be manually set to 0 (zero);
- Via the CTP, MIN/LDG, LDG ELEV, MAN;
- On any MFW, MISC page, AVIONICS Tab.
Where is the cabin pressure and landing elevation information depicted?
- Below the fuel quantities on the EICAS, or
- On the BLEED Synoptic page.
Which Stages in the HPC (High Pressure Compressor) is Bleed Air extracted?
- 4th Stage LP Bleed;
- 7th Stage MP Bleed (Starting engine & Cowl anti-ice);
- 10th Stage HP Bleed.
Note: Wing Anti-Ice is supplied from the 4th and 10th stage (depending on demand).
When is the HPV (High Pressure Valve) prevented from opening?
When N2 is Less than 55%.
During ground operation, what is the priority bleed source for Engine starting?
- 1st APU Bleed Air;
- 2nd External High-Pressure ground connection;
- 3rd Crossbleed.
How are Hot Bleed Air leaks monitored?
- Dual Loop sensing elements (Loop A & B) are routed along the HP ducts and monitored by the IASCs
(Integrated Air System Controller).
What occurs automatically when a bleed air leak is detected?
IASCs automatically close the bleed air valve that supplies the affected duct.
How is a bleed leak depicted on the BLEED Synoptic page?
- Amber Flow Lines;
- The corresponding valves are closed.
What happens to the PACK airflow schedule when Heating/Cooling Demand is High?
- PACK FLOW HI schedule is automatically selected by the IASCs to drive maximum airflow.
What are the 2 functions of the Air Conditioning Packs?
- Decrease the air temperature;
- Decrease the water contained in the Hot Bleed Air.
When do the AISCs automatically close the Flow Control Valves?
When a pack fails and either the DITCHING PBA is selected ON or a Pack System fault is detected.
Which valves close when selecting the TRIM AIR PBA switch to OFF?
- All 4 Trim Air Valves;
- Both HASOV (Hot Air Shutoff Valve).
When is Manual operation of the APU BCV (Bleed Control Valve) not possible?
- Anti-Ice is Active;
- LH Engine PRV (Pressure Regulating Valve) is manually opened;
- RH Engine PRV (Pressure Regulating Valve) & the Crossbleed Valve are manually opened.
What are the two functions of the RAM AIR System?
- Alternate source of fresh air at altitudes less than 15,000 ft.
- Cool the packs and APS (Air Preparation System) Heat Exchangers;
What malfunction will require the use of AUX PRESS?
Failure of both Packs.
What is the Altitude Limitation for using the AUX PRESS?
Prohibited above 41,000 ft.
What are the typical Cabin Altitudes for FL 510 and FL 450?
- FL 510: 5,670 ft
- FL 450: 4,500 ft
Describe the two modes of operation with the CPCS (Cabin Pressure Control System) in AUTO:
- Primary Mode (Predictive): FMS has an active flight plan with altitude, AP is on, VNAV on.
- Secondary Mode (Reactive): Uses airplane Altimeter and Vertical Speed (ADC).
