Engine Fuel And Fuel Metering System Flashcards
Gasoline and other liquid fuels do not burnt at all, unless they are mix with what other elements 
Mix with air
Where are the fuel spray nozzle located in a turbine engine?
Either externally or internally on the combustion chamber in such a way that fuel can be sprayed into the combustion area
name the heat sources for operation of fuel heaters used in turbine engines
Bleeder as air to liquid heat exchanger, engine lubricating oil as liquid to liquid heat exchanger
What engine variables are sensed by Hydro mechanical fuel control
Power lever position, rpm, compressor inlet pressure temperature, burner pressure or compressor Discharge pressure and EGT or TIT
In an electrical fuel control system,what are the two import components
Electrical and fuel
What are the two most commonly used carburetor in a small reciprocating engine?
Float type and pressure type
What type of fuel control unit is used in a turbine engine
Both Hydro mechanical and electronic fuel control. Most common unit control is the Hydro mechanical type.
What is meant by trimming a turbine engine?
 adjusting fuel control for proper specific gravity of the fuel and for proper idle and full throttle rpm
When should a turbine engine be trimmed?
When there is a loss of engine, power or manufacturer specified
What specification are used to trim a turbine engine
 Data plate on engine typically contains trimming specification
What are the three type of fuel controls for turbine engines?
Supervisory EEC (electronic engine control) ,FADEC and mechanical
What is FADEC
full authority digital electronic control is high precision digital electronic fuel control that use electronic engine control and a flight management computer to measure the fuel nozzle that prevent over temperature and over speed conditions. It also sends information to the education system for the aircraft crew.
Does an engine control by FADEC required manual trimming
 No, it is self-trimming
What is the purpose of a mixer control in a float type carburetor?
Controls the fuel air mixture as air density change with altitude change
What is the purpose of an accelerating system on a flow type carburetor
When the throttle is open rapidly, the fuel air mixture will lean out momentarily, to overcome tendency a charge of fuel from the accelerating pump will temporarily enrich the mixture in the Venturi
Describe the purpose and operation of Venturi
Is an example of Bernoulli principle as the velocity of a gas or liquid increases, the pressure decrease. Venturi performs three function. 1-proportion to fuel air mixture .
2-lower the pressure at discharge nozzle.
3-and limit the airflow at full throttle. The carburetor depends on differential between the atmospheric pressure, and decreased pressure offered by Venturi
What is the function of a metering jet
To limit the fuel flow when the throttle valve is wide open
What is the fuel metering force in a float type carburetor?
The differential pressure between the pressure in a flow chamber and at the nozzle
What will be the result of using excessively rich idle mixtures?
Carbon fouling of spark plug
What is the purpose of economizer system in float type carburetor
Valve, which is closed at throttle setting below 60% to 70% rate power, by provide additional fuel for engine cooling to prevent detonation a higher throttle setting above 60%to 70%
Where does the pressure injection carburetor obtain fuel pressure
Form boost pump for starting and engine driven pump during normal operation
What operates an automatic mixture control on a pressure carburetor
Seal bellows that expand or contract with changes in atmospheric pressure. The movement of the Bellow operate a Tapered needle that controls the impact air pressure into A chamber of carburetor
In what position do you place the mixture control of a pressure injection carburetor to stop engine ?
Idle cutoff position
What rpm indication should result when the mixture control is placed in the idle cutoff position when the idle mixture is set correctly ?
Should be slight drop in rpm, follow by a rapid drop of rpm to zero
What is the purpose of filling a pressure injection carburetor full of fuel and allowing it to soak for a period of about eight hours prior to installation
To soften the diaphragms and make them as pliable as they were when the carburetor was originally calibrated
What are three type of carburetor icing
Throttle icing, impact icing and fuel evaporation icing
What is the typical fuel pressure in a float type carburetor
3-5 psi
Name some advantage of direct fuel injection system system over conventional carburetor system
Less danger of induction system icing , improve acceleration , improved fuel distribution, reduced overheating of individual cylinders, better fuel economy
What is the purpose of filter in a fuel system
Prevent foreign matter from entering the carburetor
Why do carburetor in aircraft have a mixture control
Air density changes with altitude, which affect the air fuel mixture. Mixture control provides a means to adjust for the correct mixture at different attitude
What two items are adjusted when setting idling conditions on float carburetor
Throttle stop for idle rpm and idle mixture though the idle needle valve
What should be looked for when inspecting engine driven pump
Look for fuel leak and security of mounting
What is the purpose of fuel selector valve?
Shutting off fuel flow, crossfeed for tank, engine selection, and for fuel transfer
What is the purpose of an engine driven fuel pump?
Always deliver continuous supply of fuel add the proper pressure during engine operation
What type of fuel pump is generally use with large reciprocating engine
Positive displacement, rotary vane type
What are the function of the boost pump?
Supplies fuel to the engine pump for starting, maintain pressure in the fuel line to prevent fuel from boiling off at altitude and act as a back up if engine driven pump fails
What are the three general causes of vapor lock?
Low fuel pressure, high fuel temperatures, excessive fuel turbulence
Turbine engine fuel pumps may be divided into two distinct system categories
Constant displacement and variable displacement
What category is a turbine engine driven gear type pump?
Constant displacement
What type of fuel pump can be made into a vary the fuel flow at any speed
Variable displacement pump
What part of a gas turbine engine fuel system is very susceptible to formation of ice
Fuel filter
How is the engine fuel system protected from ice formation?
Use fuel heaters
Why is a micron filter provided with bypass valve as a necessary safety factor?
Small opening in this type of filter makes it very easy to clogging
Where are the fuel filter located?
At the fuel pump in line with the system. Last chance filter screens are in the fuel control
Can you use automotive gasoline in a reciprocating engine in place of avgas?
Yes, if you have a STC
What is the purpose of pressurizing portion of a pressurizing and dump valve?
To provide primary and secondary fuel flow to dual line duplex fuel nozzle
What is the divided fuel flow of a turbine engine duplex fuel nozzle produce in the fuel
Two spray pattern
