Engines Flashcards
What engines are installed on the CRJ-700?
Two fuselage mounted General Electric CF34-8C5 engines.
What controls the engine during normal operations?
The Full Authority Digital Engine Control System (FADEC).
What is the normal Takeoff and Go-Around thrust rating?
12,670 pounds of thrust
What is the Automatic Performance Reserve (APR) thrust rating?
13,790 pounds of thrust
What is the definition of Bypass Air?
Air that is accelerated by the single stage N1 fan and is ducted around the engine nacelle to produce most (80%) of the thrust generated at takeoff.
What is the definition of Core Air?
Air accelerated by the N1 fan that enters the N2 core where it is compressed, mixed with fuel and ignited. The resulting combustion gases are then exhausted onto the high pressure turbines to drive the N2 assembly. The exhaust gases are then discharged onto the low pressure turbines to drive the N1 fan. Jet pipe thrust accounts for a smaller portion (14%) of the thrust generated at takeoff.
What is the function of the N1 fan Inlet Temperature Probe (T2)?
It provides temperature data to the FADEC to set engine thrust (power) and control the variable geometry
What is the maximum ITT to introduce fuel during a ground start?
120 degrees C
What is the maximum ITT to introduce fuel during an in flight start?
90 degrees C
What is the function of the Low Pressure Turbine Assembly?
It powers the N1 Compressor
What is the function of the High Pressure Turbine Assembly?
It powers the N2 Compressor.
How many stages comprise the high pressure compressor (N2)?
10
What is the definition of variable geometry (VG) axial flow compressor?
The variable geometry (VG) system regulates airflow across the N2 compressor by changing the position of the inlet guide vanes and the stator vanes for the first four stages of the compressor.
What is the function of the Inlet Guide Vanes?
The inlet guide vanes direct the N1 discharge air into the compressor inlet (core) at the correct angle of attack to minimize turbulence.
What is the function of the Operability Bleed Valve?
The operability valve extracts bleed air to offload the compressor during engine starts and during high aerodynamic loading of the compressor.
What controls the variable geometry (VG) compressor and the operability valve?
The operability valve is programmed by the FADEC and hydraulically activated by high pressure fuel from the engine’s fuel metering unit.
What mechanical force drives the variable geometry compressor (VG), inlet guide vanes and operability valve?
High pressure fuel from the engine’s fuel metering unit).
What are the uses for the engine fuel system besides providing fuel for combustion?
- Actuate the VG compressor linkage
- Operate the operability valve
- Cool the engine oil (heat transfer)
- Actuate & lubricate the fuel system components
- Provide motive flow for the scavenge & main ejectors
What is the function of the Full Authority Digital Electronic Control (FADEC)?
The FADEC is a two-channel digital electronic control computer that controls the fuel flow and the airflow to the engine.
How many FADEC units are installed on each engine?
One
How many channels comprise each FADEC unit?
Two
What is the function of the FADEC channel operating in standby mode?
The standby channel of the FADEC processes all the input information but does not provide control output. It automatically provides output control if the operating FADEC fails.