What are 3 primary functions of the Fuel control system?
- Meter fuel
- Provide overspeed protection
- Provide fuel cutoff
In a governor flyweight assembly, what does on speed, over speed and under speed meas?
- on speed-fly weights=speeder spring tension
- under speed-speeder sring>flyweights
- overs speed-speeder spring<flyweights
The difference in fuel pressure felt across metering valve is compensated by ?
Delta P valve
What's not a required input for the FCU?
What are 3 inputs for the N2 governor?
What are the 4 lines that attach to the N2 governor?
What provides the fuel scheduling from start up to ground idle?
What are 5 lines that would normally be found on the fuel pump?
- Fuel input
- fuel output
- fuel bypass
- filter in
- filter out
What are 2 types of fuel nozzles?
Simplex and Duplex
In a duplex nozzle, when does fuel come through the primary holes? secondary holes?
- pri- low speed
- sec-increase in pressure pushes spring down to open at high speeds
What is a common precaution when handling fuel nozzles?
What is the most efficient spray pattern?
- Don't touch the end of the nozzle, effects spray pattern
- Finely Atomized Spray is most efficient
What is incorperated into a simplex nozzle to slow the atomized fuel down so it will burn?
What are some of the tasks that can be done with a FADEC system?
- Fault detection
- Auto Start
- Auto relight
- Auto Overspeed protection
- Surge Protection
What do the follow ancronyms mean?
- Rotor speed
- compressor speed
- power turbine speed
- comp discharge air
- governor pressure
- ambient air pressure
- governored air pressure
What does FADEC stand for?
Full Authourity Digital Electronic Control
What does TMOP and MGT stand for?
- Measured gas temp
- Torque metered pressure
What is the function of the flw divider in the Pratt fuel system?
Shuttles over to set primary or secondary fuel nozzle
What are some adjustments that can be made on the FCU?
- Acceleration adjustments
- idle speed
- max govering speed
- part power trim stop
In a FADEC system, what are the 3 faults called?
- Fadec Degrade-may effect engine proformance,
- Fadec Fault-may effect engine operating features such as engine limiting
- Restart Fault-engine may not start in auto
How are N1, N2 and Nr measured
uses mono pole pickups to count the number of teeth over time
How does the auto relight system know when to fire?
- looks for N1, ITT and torque
- Initiated if ECU detects flame out, annunciator light will stay illuminated during the duration
What is setting the Ng idle speed?
idle screw in speeder spring
What is the relationship between Px and Py when the governor is onspeed?
In a PT-6 engine what comps for altitude to give an absolute pressure reference?
What would happen if the acceleration bellows had a hole in it?
engine would go to min fuel flow