Endeavor CRJ900 systems: Powerplant,
Fuel, Fire UPDATED ACTUAL Questions
and CORRECT Answers
What does the N1 section consist of? - CORRECT ANSWER - 28-blade titanium fan
4 stage low pressure turbine
What does the N2 section consist of? - CORRECT ANSWER - 10 stage axial compressor
2 stage high pressure turbine
What is the normal takeoff thrust? - CORRECT ANSWER - 13,600 lbs/ 14,510 with APR
Describe how the engine operates through the following stages; Intake, Compression,
Combustion, Exhaust - CORRECT ANSWER - Comes in through N1 section, most
bypassed, compressed in 10 stage axial flow compressor (N2), annular combustion chamber, 2
stage high pressure turbine (drives N2) then 4 stage low pressure turbine (drives N1), finally
exhaust
What percentage of engine air is bypass, and what percentage is core air? - CORRECT
ANSWER - 85% bypass, 15% core
What is different about the first four stages of the N2 compressor section? - CORRECT
ANSWER - FADEC controlled variable geometry
Describe the function and actuation of the Variable Geometry System - CORRECT
ANSWER - High pressure fuel is used to physically move the stators and inlet guide vanes
to prevent compressor stalls and surges (FADEC controlled)
How is the position, of the Variable Geometry System, controlled? - CORRECT
ANSWER - FADEC via high pressure fuel
, Describe the function of the Operability Valve - CORRECT ANSWER - Relieves pressure
in the system to prevent compressor stall/surge
What actuates the Operability valve? - CORRECT ANSWER - FADEC using high
pressure fuel from the fuel control unit
Which components are located on the Accessory Gear Box (AGB) 900SM 22-3 - CORRECT
ANSWER - 3 PUMPS: Hydraulic pump, Fuel pump, Engine lubrication Oil pump
2 ELEC: IDG, FADEC Alternator
1 AIR Turbine Starter.
From which compressor stages do we receive bleed air, and for what purposes? - CORRECT
ANSWER - 6 th stage low pressure and 10 th stage high pressure into the common bleed
manifold for ECS (Environment Control System), Anti-Ice, and Engine Starts.
How many igniters exist in the combustion section, and what are their power sources?
Are igniters AC or DC? - CORRECT ANSWER - 2 igniters
A: AC Ess Bus
B: DC Batt Bus (converts to AC)
Igniters are AC only
How can the Battery bus be the power source of Ignition B when both igniters use AC power? -
CORRECT ANSWER - Channel B includes an Inline Static Inverter to create the needed
AC power.
It just so happens that during a battery start, Ignition A is the active ignition. How will you be
able to start the engine? - CORRECT ANSWER - After 15 seconds FADEC will realize
the igniter isn't powered and will switch to the other channel, in this case channel B
Fuel, Fire UPDATED ACTUAL Questions
and CORRECT Answers
What does the N1 section consist of? - CORRECT ANSWER - 28-blade titanium fan
4 stage low pressure turbine
What does the N2 section consist of? - CORRECT ANSWER - 10 stage axial compressor
2 stage high pressure turbine
What is the normal takeoff thrust? - CORRECT ANSWER - 13,600 lbs/ 14,510 with APR
Describe how the engine operates through the following stages; Intake, Compression,
Combustion, Exhaust - CORRECT ANSWER - Comes in through N1 section, most
bypassed, compressed in 10 stage axial flow compressor (N2), annular combustion chamber, 2
stage high pressure turbine (drives N2) then 4 stage low pressure turbine (drives N1), finally
exhaust
What percentage of engine air is bypass, and what percentage is core air? - CORRECT
ANSWER - 85% bypass, 15% core
What is different about the first four stages of the N2 compressor section? - CORRECT
ANSWER - FADEC controlled variable geometry
Describe the function and actuation of the Variable Geometry System - CORRECT
ANSWER - High pressure fuel is used to physically move the stators and inlet guide vanes
to prevent compressor stalls and surges (FADEC controlled)
How is the position, of the Variable Geometry System, controlled? - CORRECT
ANSWER - FADEC via high pressure fuel
, Describe the function of the Operability Valve - CORRECT ANSWER - Relieves pressure
in the system to prevent compressor stall/surge
What actuates the Operability valve? - CORRECT ANSWER - FADEC using high
pressure fuel from the fuel control unit
Which components are located on the Accessory Gear Box (AGB) 900SM 22-3 - CORRECT
ANSWER - 3 PUMPS: Hydraulic pump, Fuel pump, Engine lubrication Oil pump
2 ELEC: IDG, FADEC Alternator
1 AIR Turbine Starter.
From which compressor stages do we receive bleed air, and for what purposes? - CORRECT
ANSWER - 6 th stage low pressure and 10 th stage high pressure into the common bleed
manifold for ECS (Environment Control System), Anti-Ice, and Engine Starts.
How many igniters exist in the combustion section, and what are their power sources?
Are igniters AC or DC? - CORRECT ANSWER - 2 igniters
A: AC Ess Bus
B: DC Batt Bus (converts to AC)
Igniters are AC only
How can the Battery bus be the power source of Ignition B when both igniters use AC power? -
CORRECT ANSWER - Channel B includes an Inline Static Inverter to create the needed
AC power.
It just so happens that during a battery start, Ignition A is the active ignition. How will you be
able to start the engine? - CORRECT ANSWER - After 15 seconds FADEC will realize
the igniter isn't powered and will switch to the other channel, in this case channel B
