Engines Flashcards
Describe T45C main components
- Single Engine
- Non-After Burning
- 2 stage low px (N1) - > Driven by single-stage low px turbine
- 5 Stage high px (N2) compressor - Driven by single stage high px turbine
-
N1 and N2 on concentric shafts and can spin freely
- Spin CW
- Produces installed static sea level thrust of 5527#’s
- 100 percent N2 is 15,512 rpm
Installed static sea level thrust
5,527 pounds
RPM of N2 at 100%
15,512 RPM
When does the bleed valve close?
61±4%
What indicates the bleed valve is closed?
- N2 idle rpm increase ~3%
- EGT decreases 50*C
When does the bleed valve close?
Once N2 reaches ~45% RPM during engine shutdown
Does the bleed valve remained closed at all flight regimes?
No the bleed valve will open dyuring airstart when the GTS start button is pressed.
It will remain open for 60 seconds after button release
What does the bleed air system do?
- Bleed air from N1 and N2 is used to seal compressor and turbine bearing compartments
- Provide cooling for turbine assemblies
- N2 (5th Stage) supplies the bleed air for the
- environmental systems and
- OBOGS/anti-g systems
- fuel tank pressurization
What stage provides the bleed air for the environmental systems?
N2 5th
What does the bleed air from the N2 5th stage do?
Gives bleed air for
- Environmental system
- OBOGS/antiG
- Fuel tank pressurization
When is the steam ingestion bleed valve open?
- Launch bar is not retracted
- WOW
- N2 RPM above 70%
- Provided by the 70% N2 switch
What caution light is associated with the steam ingestion valve?
- ACCEL caution light when the valve position does not match the commanded position
- 2 second delay prevents transient warning
- ACCEL indicates
- Steam Ingestion valve not in commanded position -or-
- shot of fuel solenoid is not in the commanded position
Describe the engine Anti-Ice system
- A small flow of bleed is air is continuously ducted through the fan N1 shaft spinner.
What is connected to the Engine Accessory Gear Box?
- Hydraulic pumps
- DC Generator
- LP Fuel pump
- HP Fuel pump
- Engine Oil Pumps
- N2 RPM Tachometer
How does the air turbine starter transmit power to rotate the N2 Shaft?
Through the accessory gear box
What makes of up the engine fuel system?
- LP fuel pump
- Fuel cooled oil cooler
- LP fuel filter
- HP fuel pump
- FCU
- 18 spray nozzles in the engine combustion chamber
Caution asscoiated with Low Pressure pump
LP PMP - Fuel pressure drops below 35 PSI
What type of fuel system does T45 have?
Flow scheduling type with acceleration control
What schedules fuel and how does it do it?
- Fuel Control Unit
- Uses throttle position and compensates the flow for
- Altitude
- Airspeed
What controls engine acceleration?
- 75 GPH shot of fuel solenoid
- Throttle valve dashpot and hydromechanical acceleration swithc
What does the shot of fuel solenoid do?
Provides increased fuel flow to reduce engine aceleartion time and provide improved engine surge contorl
What does the throttle valve dashpot do?
Ensures that the throttle valve opens at a rate to give the max stall free acceleartion regardless of the rate of throttle movement.
Shot of fuel solenoid altitudes of operation
- Always open below 7200’ MSL
- Open on the ground and remains open until climbing through 9500 ±300’MSL and reopens when descending 7700±500’ MSL
- Acuated to approach mode when below 6500’
When does MFUEL caution come on?
When manual fuel system is selected
How does manual fuel system work?
The system bypasses the control elements downstream of HP pump.
There is no automatic control of
- N1
- N2
- EGT
All fuel metering is done with direct conection to throttle setting
How is engine operation different when using the manual fuel system vs the main fuel system?
- Airstarts may require throttle modulation due to bypassing of the Sub Idle Fuel Control Unit (SIFCU)
- Retarding the throttle to IDLE results in lower than normal idle N2 rpm
- Dashpot accel is inop so engine accel at lower altitude are significantly slower than usual
- at higher altitudes it will be faster
- Bleed valveremains closed at all engine speeds expect during airstat when it is held open with60 second timer
- To keep N1 within limits
- N2 RPM should not exceed 95% below 20,000’ MSL
- -or- 90% above 20,000’ MSL
Can you start the engine with the manual fuel system?
No NATOPS prohibits
Can you switch to MFUEL with complete loss of electrical power?
No.
What is the SIFCU and what does it do?
Sub Idle Fuel Control Unit and it meters fuel to spray nozzles during the start cycle
What is the ECA and what does it do?
Engine Control Amplifier and it automatically prevents overspeed and overtemp conditions by controling fuel flow.
What does the ECA monitor?
N1 shaft speed and two sets of thermocouples located behind the N1 turbine section
What sets off the EGT/RPM caution light?
When ECA reads EGT > 650±8*C or N1 >112.4±1%
What is the total oil capacity?
25.2 US pints
How much is the unusable oil?
9.6 US pints
Max Oil Consumption
Max oil consumption rate is 0.8 US pint/hour
How many sacavenge pumps are there?
3
How does the OIL PRESS warning work?
If the differential of the scavenge oil and the internal gearbox drops below 10 PSI
How many igniters are there?
Two 12 joul dc ignition units
What controls the ingntion?
ECA and starter control unit
Weight on wheels ignition conditions
- The GTS start button is pressed, ignition ceases immediately when the button is released
- The ENGINE switch is set to START and the READY advisory lightis on.
- Ignition is continuous until the engine reaches 45% RPM or after 45 seconds when igntion terminated and GTS returns to idle
When is ignition provided in the air? (Weight off Wheels)
- GTS start button is pressed and continues for 30 seconds after the button is released
- ENGINE switch is set to START and the READY advisory light is on. Ignition is continuous until engine reaches 45% N1 or after 45s when ignition auto terminated and GTS idles
