ERJ 175 ECS QUESTIONS &
SOLUTIONS
What does the AMS use bleed air for? (6) - ANSWER WHEEEP
-Water Pressure
-Hot air leak detection
-ECS heating and cooling
-Engine Start
-Engine and wing anti ice
-Pressurization
Where is the external ground source panel located? - ANSWER Lower fairing between
the wings
What is the primary use for APU bleed air? (4) - ANSWER BAEE
-Bleed source for pressurization, heating, and cooling below 15,000 ft MSL
-Assist with engine start below 21,000
-Engine start on the ground
-ECS on the ground
Can engine bleed air flow-back to the APU? - ANSWER No. A check valve prevents
flow back.
Where is bleed air tapped from the engines? - ANSWER The 6th and 10th stages of the
compressor. The system automatically alternates between values to regulate an
adequate and safe pressure.
What must the bleed pressure be for an engine start? - ANSWER 40-45 psi
What is the purpose of the pre-cooler? - ANSWER Cools the bleed air after coming from
the compressor before going to the AMS.
What cools the pre-cooler? - ANSWER On the ground, the N1 fan.
In flight, the N1 fan or ram air.
What components does the overheat detection system check? - ANSWER APPE
-APU bleed
-Plumbing for the wing and engine anti icing system
-Packs
-Engine bleeds
Do both loops have to function in order to detect on overheat condition? - ANSWER No,
if one fails then the other will work alone to detect the overheat condition.
, How many ECS packs are on the airplane? - ANSWER 2
What provides air for the packs? - ANSWER -2 independent packs (left and right)
-Each engine provides bleed air to its respective pack
-APU
Can a single pack provide adequate temperature control and pressurization? -
ANSWER Yes, up to 31,000 feet
What is the ratio of fresh air to recirculated air? - ANSWER 52% fresh to 48%
recirculated
When are the recirculation fans commanded off? - ANSWER -Dump button is pressed
-Both packs are OFF
-The recirculation cockpit switch is pressed
-Smoke is detected in the recirculation bay
-The cargo bay fire signal activates
When is emergency ram air ventilation activated? - ANSWER -If the outside air
pressure is higher than the inside of the cabin.
-If both packs are off below 25,000ft.
-The emergency ram air ventilation is on the left side and electronically controlled.
Where does the cabin pressure controller get landing field elevation? - ANSWER The
FMS, or it can be manually selected.
What happens when the dump button is pressed in AUTO mode? - ANSWER -Both
packs turn off
-Recirculation fans turn off
-It opens the outflow valve and raises the cabin to 12,400 ft at 2,000 fpm and continues
to leak.
Can the cabin altitude be raised higher than 12,400 ft after the dump button is pressed?
- ANSWER -Yes, manually
-Cabin altitude will rise due to natural leak
In manual mode will the cabin depressurize on landing? - ANSWER No
What is the bleed system priority in flight? - ANSWER -Onside engine
-Opposite side engine
-APU if available
If both engine and APU bleed air are available at the same time, which has priority? -
ANSWER -The APU has priority if the aircraft is on the ground and slower than 50kts
SOLUTIONS
What does the AMS use bleed air for? (6) - ANSWER WHEEEP
-Water Pressure
-Hot air leak detection
-ECS heating and cooling
-Engine Start
-Engine and wing anti ice
-Pressurization
Where is the external ground source panel located? - ANSWER Lower fairing between
the wings
What is the primary use for APU bleed air? (4) - ANSWER BAEE
-Bleed source for pressurization, heating, and cooling below 15,000 ft MSL
-Assist with engine start below 21,000
-Engine start on the ground
-ECS on the ground
Can engine bleed air flow-back to the APU? - ANSWER No. A check valve prevents
flow back.
Where is bleed air tapped from the engines? - ANSWER The 6th and 10th stages of the
compressor. The system automatically alternates between values to regulate an
adequate and safe pressure.
What must the bleed pressure be for an engine start? - ANSWER 40-45 psi
What is the purpose of the pre-cooler? - ANSWER Cools the bleed air after coming from
the compressor before going to the AMS.
What cools the pre-cooler? - ANSWER On the ground, the N1 fan.
In flight, the N1 fan or ram air.
What components does the overheat detection system check? - ANSWER APPE
-APU bleed
-Plumbing for the wing and engine anti icing system
-Packs
-Engine bleeds
Do both loops have to function in order to detect on overheat condition? - ANSWER No,
if one fails then the other will work alone to detect the overheat condition.
, How many ECS packs are on the airplane? - ANSWER 2
What provides air for the packs? - ANSWER -2 independent packs (left and right)
-Each engine provides bleed air to its respective pack
-APU
Can a single pack provide adequate temperature control and pressurization? -
ANSWER Yes, up to 31,000 feet
What is the ratio of fresh air to recirculated air? - ANSWER 52% fresh to 48%
recirculated
When are the recirculation fans commanded off? - ANSWER -Dump button is pressed
-Both packs are OFF
-The recirculation cockpit switch is pressed
-Smoke is detected in the recirculation bay
-The cargo bay fire signal activates
When is emergency ram air ventilation activated? - ANSWER -If the outside air
pressure is higher than the inside of the cabin.
-If both packs are off below 25,000ft.
-The emergency ram air ventilation is on the left side and electronically controlled.
Where does the cabin pressure controller get landing field elevation? - ANSWER The
FMS, or it can be manually selected.
What happens when the dump button is pressed in AUTO mode? - ANSWER -Both
packs turn off
-Recirculation fans turn off
-It opens the outflow valve and raises the cabin to 12,400 ft at 2,000 fpm and continues
to leak.
Can the cabin altitude be raised higher than 12,400 ft after the dump button is pressed?
- ANSWER -Yes, manually
-Cabin altitude will rise due to natural leak
In manual mode will the cabin depressurize on landing? - ANSWER No
What is the bleed system priority in flight? - ANSWER -Onside engine
-Opposite side engine
-APU if available
If both engine and APU bleed air are available at the same time, which has priority? -
ANSWER -The APU has priority if the aircraft is on the ground and slower than 50kts
