Term
| What are some sources used to heat the fuel in a turbine engine fuel system |
|
Definition
Bleed air or
Lubricating oil |
|
|
Term
| What are the most common types of fuel metering systems used on small reciprocating engines |
|
Definition
Float type carburetor
Pressure injection carburetor or
Direct fuel injection system |
|
|
Term
| What function does the mixture control perform |
|
Definition
| Controls fuel air mixture |
|
|
Term
| What generally causes spark plug fouling |
|
Definition
| Operating engine with an excessively rich mixture at idle |
|
|
Term
| What is the purpose of an accelerating system |
|
Definition
| Provides a immediate but brief increase in fuel flow to the venturi to enrich the mixture |
|
|
Term
| What is a carburetor economizer system |
|
Definition
| A power enrichment system that provides a richer mixture at high power settings |
|
|
Term
| When the mixture is placed in the idle cutoff position, a slight rise in r.p.m. is noted prior to the engine decelerating, what does this indicate? |
|
Definition
| The idle mixture is set correctly |
|
|
Term
| Why should engine r.p.m. be accelerated periodically when making carburetor adjustments? |
|
Definition
|
|
Term
| What maintains fuel pressure in a pressure-injection carburetor |
|
Definition
|
|
Term
| What happens if the manual mixture control of a pressure injection carburetor is moved to the idle cutoff position |
|
Definition
|
|
Term
| How does the automatic mixture control function |
|
Definition
A sealed brass bellows, connected to the fuel metering system, expands and contracts
w/changes in pressure and temperature, adjusting the mixture accordingly |
|
|
Term
| What are some advantages of fuel injection over carburetor systems |
|
Definition
Less induction icing
Better acceleration
Better fuel distribution
Better fuel economy
Reduced over heating of individual cylinders |
|
|
Term
| What purpose do turbine engine fuel control units serve |
|
Definition
| They automatically meter fuel to the engine |
|
|
Term
| What are 2 basic types of turbine engine fuel control units |
|
Definition
Hydromechanical
Electronic |
|
|
Term
| What are the engine variables detected by the fuel control unit |
|
Definition
Power lever position
Engine r.p.m.
Compressor inlet temp
Compressor inlet pressure
Compressor discharge pressure
Burner pressure |
|
|
Term
| what are the 2 major components of a supervisory electronics engine control |
|
Definition
electronic control unit,
hydro-mechanical fuel control |
|
|
Term
| what are some of the advantages of a full-authority digital engine control over a hydro-mechanical fuel control |
|
Definition
-better fuel economy
-improved starts
-no engine trimming
-provides engine limit protection
-provides constant idle speeds
-fully modulates the active clearance controls
-allows more repeatable engine transients |
|
|
Term
| what do turbine engine fuel spray nozzles do |
|
Definition
| they inject fuel into the combustion area |
|
|
Term
| what are the different engine indications used for trimming a turbine engine |
|
Definition
| EPR or r.p.m is used depending on the particular engine |
|
|
Term
| what maintenance adjustments are normally allowed on an installed hydro-mechanical fuel control |
|
Definition
-specific gravity for fuel
-idle r.p.m.
-max. r.p.m. |
|
|
Term
| what type of pump can vary the amount of fuel discharged regardless of speed |
|
Definition
| variable displacement pump |
|
|
Term
| what is used to keep water, sediment, and foreign matter out of the carburetor |
|
Definition
|
|
Term
| what is the purpose of a pressure relief valve in a constant displacement pump |
|
Definition
| returns excess fuel that is not required by the engine to the inlet side of the pump |
|
|
Term
| what type of engine-driven fuel pump is widely used other than gear or piston pumps |
|
Definition
|
|
Term
| what function do fuel boost pumps perform |
|
Definition
| supply pressurized fuel to the fuel pump, which helps prevent vapor lock and cavitation |
|
|
Term
| what is a commonly used type of fuel boost pump |
|
Definition
|
|
Term
| what causes vapor lock and why is it of concern |
|
Definition
| caused by insufficient fuel pressure, high fuel temp., and excessive fuel turbulence, which may block any fuel resulting in engine failure |
|
|
Term
| what function does the engine-driven pump on a turbine engine perform |
|
Definition
| provides a continuous supply of fuel at the proper pressure while the engine is running |
|
|
Term
| name the 2 categories of turbine engine pumps |
|
Definition
| constant and variable displacement |
|
|
Term
| what category is a gear-type pump classified in |
|
Definition
|
|
Term
| when performing an external inspection of an engine-driven fuel pump, what should you look for |
|
Definition
| leaks and security of mounting |
|
|
Term
| what is the purpose of a shear section of the drive shaft in a dual element constant displacement pump |
|
Definition
| if one element seizes, a portion of the drive shaft seizes, allowing the other element to continue to operate |
|
|
Term
| where in a turbine engine fuel system is ice formation likely to occur and how is it prevented |
|
Definition
| fuel filter- a heat exchanger using oil or bleed air to warm fuel |
|
|
Term
| what is the purpose of a bypass valve in an engine fuel system micron filter |
|
Definition
| it is a safety feature that allows fuel to flow to the engine if the filter becomes blocked |
|
|
Term
| what is the purpose of a duplex fuel nozzle |
|
Definition
| discharges 2 different spray patterns, a wider one during start up and a narrow one when engine speed increases above idle |
|
|
Term
| what are the functions of the pressurizing and dump portions of a pressurizing dump valve |
|
Definition
| the pressurizing portion provides primary and secondary fuel flow to dual-line duplex fuel nozzles, and the dump portion allows fuel to drain from the manifolds after engine shutdown |
|
|
Term
| what purpose do fuel selector valves serve |
|
Definition
| allow tank and engine selection, and provide a means for shutting off fuel flow |
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