Aviation A&p Powerplant ( Fuel Metering Systems )

Front 1

Where does the fuel metering system of a turbine engine discharge its fuel ?

Back 1

The fuel is discharged through spray nozzles into the combustion chambers.

Front 2

What is adjusted when the fuel control unit of a turbine engine is trimmed ?

Back 2

The idle speed and the maximum-thrust speed.

Front 3

What are two locations water may be injected into a turbine engine ?

Back 3

At the compressor inlet and at the inlet to the diffuser section.

Front 4

What is meant by a duplex nozzle in a turbine engine fuel metering system ?

Back 4

A duplex fuel nozzle is one that has two fuel discharge passages.

A flow divider sends fuel for low-pressure operation through one dischagre passage, and when the engine demands more fuel, it is sprayed out through the second discharge passage.

The spray pattern keeps the flame centered in the burner for all operating conditions.

Front 5

What is the function of a float carburetor ?

Back 5

The float carburetor's function is to measure airflow through the engine induction system and dispense the appropriate amount of gasoline into the airflow for all engine operating perimeters and conditions. It must also provide the fuel in a state that is as vaporized as possible by the time ignition occurs in the engine cylinders.

Front 6

Does the fuel-air mixture provided by a float carburetor become richer or leaner as the aircraft goes up in altitude ?

Back 6

If the mixture is not adjusted, it will become richer as the aircraft gains in altitude.

Front 7

Does the fuel-air mixture provided by a float carburetor become richer or leaner when carburetor heat is applied ?

Back 7

The mixture becomes richer when carburetor heat is applied.

Front 8

What would happen to the fuel-air mixture ratio in a ratio in a float carburetor if the main air bleed were to become plugged ?

Back 8

The mixture would become excessively rich.

Front 9

How does the automatic mixture control in a pressure carburetor keep the fuel-air mixture constant as the aircraft changes altitude ?

Back 9

It automatically, and progressively, bleeds the air between the two sides of the air diaphragm and decreases the air metering force.

This leans the mixture as the aircraft goes up in altitude.

Front 10

What are the two purposes of the manifold valve ( or flow divider ) in the fuel injection system of a horizontally opposed aircraft engine ?

Back 10

It provides a constant discharge fuel pressure for idling, and it provides a positive shutoff for the fuel when the engine is shut down.

Front 11

How does the mixture control change the fuel-air mixture ratio on the Teledyne-Continental fuel injection system ?

Back 11

When the mixture control is in its Full Rich position, all fuel goes to the manifold valve.

When it is in the Idle Cutoff position, all fuel is returned to the pump inlet.

Intermediate positions vary the amount of fuel that goes to the engine.

Front 12

Why must the diaphragms of a pressure carburetor be soaked before the carburetor is ready for flight ?

Back 12

Soaking the diaphragms of a pressure carburetor restores them to the condition of flexibility that they had when the carburetor was calibrated.

Front 13

What are two basic types of fuel controls for aircraft turbine engines ?

Back 13

Hydropneumatic and electro-hydromechanical.

Front 14

How does the exhaust gas temperature of a reciprocating engine tell anything about the fuel-air mixture being burned by the engine ?

Back 14

A stoichiometric mixture ( a mixture in which all of the constituents of the fuel-air mixture are burned ) produces the highest exhaust gas temperature.

The mixture is adjusted to get the highest EGT, and then it is enriched to place it on the rich side of stoichiometric.

Front 15

What are two things are adjusted when adjusting the idling of a reciprocating engine ?

Back 15

The throttle stop, to get the proper idling RPM, and the idle mixture control, to get the smoothest operation.

Front 16

What is controlled by the adjustment of the orifice in the fuel pump of a Teledyne-Continental fuel injection system ?

Back 16

The high unmetered fuel pressure.

Front 17

What is the significance of the letters that are stamped on the flats of a fuel injection nozzle ?

Back 17

These letters designate the relative size of the orifice in the injector nozzle.

The lower the letter in the alphabet, the smaller the amount of fuel the nozzle will flow.

Front 18

What is the function of the economizer system in an aircraft engine carburetor ?

Back 18

The economizer (or power enrichment) system allows the engine to operate with an economically lean mixture for all conditions other than full power.

When the throttle is opened for full power, the power enrichment system automatically enriches the mixture to remove some of the heat that is developed during this type of operation.

Front 19

What is the function of the derichment valve in a pressure carburetor used on an aircraft engine with an antidetonation injection system ?

Back 19

The derichment valve automatically closes to lean the fuel-air mixture when ADI fluid is flowing.

As soon as the ADI fluid stops flowing, the derichment valve opens and the mixture returns to its rich condition.

Front 20

In what position is the mixture control placed for starting an engine that is equipped with a pressure carburetor ?

Back 20

In the Idle Cutoff position.

The engine is started with fuel from the primer system.

Front 21

In what position is the carburetor heat control placed when starting an aircraft engine ?

Back 21

In the Cold position.

Front 22

Why is an aircraft reciprocating engine killed by placing the mixture control in the Cutoff position, rather than using the magneto switch ?

Back 22

By shutting off the fuel to the cylinders, the combustion chambers are left full of air with no fuel.

This makes the engine less likely to fire if the propeller is pulled through with the ignition switch accidentally on.

Front 23

Where is the fuel from a continuous-flow fuel injection system discharged ?

Back 23

It is discharged through injector nozzles screwed into the cylinder heads near the intake valves.

Front 24

In which direction relative to the wind should a turbine-powered aircraft be positioned when the fuel control is being trimmed ?

Back 24

If the wind velocity is less than 10 miles per hour, it can be faced in any direction.

If the wind velocity is between 10 and 25 MPH, it should be trimmed facing into the wind.

The engine should not be trimmed when the wind velocity is more than 25 MPH.

Front 25

What engine parameters are sensed by the fuel control unit of a turbine engine ?

Back 25

Engine RPM, inlet air pressure, compressor discharge pressure, burner can pressure, and inlet air temperature.

Front 26

When does the acceleration system operate on an aircraft carburetor ?

Back 26

When the throttle is suddenly opened.