Systems - Powerplant Flashcards
What is the maximum normal takeoff thrust setting for the 700 and 900?
700 = 12,670lbs
900 = 13,600lbs
Describe the compressor and turbine section for N1
1 fan,
4 stage low pressure turbine
Describe the compressor and turbine section for N2
10 stage axial flow compressor, 2 stage to high pressure turbine
What percentage of engine air is bypass?
85% bypass, 15% core air
What is different about the first 4 stages of the N2 compressor section?
The first 4 stages have variable stater veins, or variable geometry system (VGVs)
Describe the function and actuation of the VGV’s
Actuated with high pressure fuel from FADEC, moves by mechanical by linkage to prevent stalls and surges
How is the position, of the variable geometry system, controlled?
FADEC changes the position of the VGV via high-pressure fuel and mechanical linkage
Describe the function of the operability valve
Provides additional compressor air flow control - extracts bleed air to offload the compressor during engine starts and high aerodynamic loading.
Programmed by FADEC and hydraulically activated by high-pressure fuel.
Which components are located on the accessory gearbox? (AGB)
3-2-1
3 pumps: hydraulic, oil, fuel.
2 sparks: IDGs & FADEC
1 ATS (Air turbine starter)
From which compressor stages do we receive bleed air and for what purpose?
6th and 10th. Used for AC, engine start, wing/cowl anti-ice and pressurization.
How many igniters exist in the combustion section, and what are their power sources?
2 AC igniter’s.
AC - A is powered by AC ESS BUS
AC - B is powered by DC BATT BUS with a static INVERTER (turning it into AC)
If during a battery start, ignition A is active, how will you be able to start the engine?
Wait 15 seconds for the “alternate” start. FADEC will control this.
Switching to ignition B stems from BATT BUS.
What happens when continuous ignition is selected?
Both ignition A and B are energized
When is continuous ignition required?
Contaminated runway, moderate or greater turbulence or rain, thunderstorms in the vicinity
When would FADEC automatically engage continuous ignition?
Close to the critical AOA, detects a disruption in airflow, or auto-relight
Where is the probe located that gives us inter turbine temperature information?
Between the high and low pressure turbines (2nd & 4th)
When will FADEC be powered by its own alternator? When will it rely on the aircraft electrical power?
Below 50% N2 or failure of FADEC - it will operate off of the aircraft power.
Above 50% N2 the AGB-Mounted FADEC alternator will operate on its own.
How many channels are on the FADEC and what if the active channel fails?
Two channels, one always active and one on standby to take over
When will the active FADEC channel switch during normal ops?
After every start at 7% N2
When will FADEC command a shut down of the engines?
Overspeed (x3) & ITT over temp on start
True or false: the thrust levers are mechanically connected to the fuel metering unit.
False, they are connected by wire
What happens if left or right FADEC fails completely?
The engine was shut down, flame out
What is APR? When would FADEC command it?
Automatic performance reserve.
ENGINE FAILURE OR if thrust levers are in the TOGA detent.
When will APR arm during takeoff?
When the N1 RPM of both engines are within 8% of schedule takeoff thrust. 
