Fuel Metering Flashcards Preview

Powerplant > Fuel Metering > Flashcards

Flashcards in Fuel Metering Deck (29):
1

What are the most common types of fuel metering systems used on small reciprocating engines

Float-type, pressure, and direct fuel injection systems

2

What function does the mixture control perform

Controls the fuel/air mixture

3

What generally causes spark plug fouling

an excessively rich mixture at idle

4

What is the purpose of an accelerating system

It provides an increase in fuel flow in the Venturi to enrich the mixture

5

What is a carburetor economizer system

provides a richer mixture at high power settings

6

When the mixture is placed in the idle cutoff position, a slight rise in rpm is noted prior to the engine decelerating. What does this indicate

Idle mixture is set correctly

7

Why should engine r.p.m be accelerated periodically when making carburetor adjustments

To clear the engine

8

What maintains the fuel pressure injection carburetor

Engine driven fuel pump

9

What purpose do turbine engine fuel control units serve

They automatically meter fuel to the engine

10

What are the two basic types of turbine engine fuel control units

Hydromechanical and electronic

11

What do turbine engine fuel spray nozzles do

They inject fuel into the combustion area

12

What are the different engine indications used for trimming a turbine engine

Either EPR or r.p.m is used depending on engine

13

What type of pump can very the amount of fuel discharged regardless of speed

A variable displacement pump

14

What is used to keep water, sediment, and foreign matter out of the carburetor

Main fuel strainer

15

What type of engine driven fuel pump is widely used other than gear or piston pumps

Rotary vane type

16

What is the purpose of a pressure relief valve in a constant displacement pump

It returns left over fuel that is not used by the engine to the inlet side of the pump

17

What function do fuel boost pumps perform

Supples pressurized fuel to the fuel pump, which helps prevent vapor lock and cavitation

18

What is a commonly used type of fuel boost pump

Centrifugal type

19

Name two categories of turbine engine pumps

Constant and variable displacement

20

What category is a gear type pump classified in

Constant displacement

21

When performing an external inspection of an engine driven fuel pump, what should you look for

Leaks and security of mounting

22

What is the purpose of a shear section of the driveshaft in a dual element constant displacement pump

If one Element seizes it allowing the other element to continue to operate

23

What is the purpose of a duplex fuel nozzle

Discharges two different spray patterns

24

What purpose do fuel selector valves serve

Allow tank and engine selection, and provide a means for shutting off fuel flow

25

What will be the result of using excessively rich idle mixtures

Cause carbon fouling of the spark plug

26

What position do you place the mixture control of a pressure injection carburetor to stop the engine

Idle cutoff position

27

What is the typical fuel pressure in a float type carburetor

3-5psi

28

What are three types of carburetor icing

Throttle, impact, and fuel evaporation icing

29

What are some of the sources used to heat the fuel in a turbine engine fuel system

Bleed air and engine lubricating oil