fuel metering systems

Characteristics of aviation gasoline are

Characteristics of aviation gasoline are

high heat value, high volatility.

The main differences between grades 100 and 100LL fuel are

lead content and color.

Why is ethylene dibromide added to aviation gasoline?

To scavenge lead oxide from the cylinder combustion chambers

What must accompany fuel vaporization

An absorption of heat.

Tetraethyl lead is added to aviation gasoline to

improve the gasoline's performance in the engine

A fuel that does not vaporize readily enough can cause

hard starting

Characteristics of detonation are

rapid rise in cylinder pressure, excessive cylinder head temperature, and a decrease in engine power

One of the best ways to increase engine power and control detonation and preignition is to

use water injection

The device that controls the ratio of the fuel/air mixture to the cylinders is called a

mixture control

(1) The mixture used at rated power in air cooled reciprocating engines is richer than the mixture used through the normal cruising range. (2) The mixture used at idle in air cooled reciprocating engines is richer than the mixture used at rated power. Regarding the above statements,

both are true

During the operation of an aircraft engine, the pressure drop in the carburetor venturi depends primarily upon the

air velocity

A gravity type fuel system must have a fuel head pressure of?

,5 to 1.5psi

Reciprocating engine power will be decreased at all altitudes if the 

humidity is increased.

An excessively lean fuel/air mixture may cause

an increase in cylinder head temperature.

Where is the engine fuel shutoff valve usually located?

aft of the firewall

A fuel strainer or filter must be located between the

tank outlet and the fuel metering device

What component controls the airflow from idle to wide open?

throttle

What component measures mass airflow and starts fuel vaporization and air/fuel mixing?

venturi

What is the purpose of the float mechanism?

It establishes the proper fuel level in the float chamber in relationship to the discharge nozzle.

What component helps atomize the fuel?

air bleeds

What does the Main Metering system provide?

It provides the fuel/air mixture for all operations above idle.

Idle adjustment is made;

With the engine operating at normal temperatures and at the lowest idle rpm setting.

Cruise is ____ to ____ of normal rated power.

45% to 70%

Where does the air bleed obtain it’s air?

behind the venturi

Which of the following is not an advantage of a fuel injection carburetor?

less accurate fuel metering

What is the letter “R” represent in the model designation of a few injection carburetor?

rectangle barrel

What is the purpose of the Venturi?

limits airflow at wide open throttle settings

The boost Venturi supplies low pressure air to what chamber?

B chamber

Of the following components is located in the adapter unit?

Discharge nozzle and fuel feed valve

What component adjusts pressure drop across the fuel control unit in proportion to the mass airflow through the throttle body?

fuel regulator unit

What is the purpose of the fuel control unit?

meters the fuel being delivered to the discharge nozzle

The power enrichment jet meters fuel between:

90-100%

What is the function of the manual mixture control valve?

To control fuel flow through the Jets

What is the function of the automatic mixture control?

Compensate for changes in air density

What is the purpose of the throttle body?

measure and control airflow

What system provides proper air fuel mixture above idle?

main metering system

The purpose of the impact tubes are:

To sample carburetor inlet air pressure for chamber "A"

Which of the following is not an advantage of the Continental TCM fuel injection system?

increased fuel economy

What type of pump is used in the Continental TCM fuel injection system?

Positive displacement rotary vane type

The relief valve diaphragm chamber in a Continental TCM injection system is vented to:

atmospheric pressure

What is the purpose of the fuel air control unit on a Continental TCM injection system?

To control engine air intake and to set metered fuel pressure

What is the purpose of the butterfly valve in a Continental TCM fuel injection system?

control flow of air to the engine

The fuel control assembly central bore on the Continental TCM fuel injection system contains two different valves. These valves are:

the metering valve and mixture control valve

The fuel manifold valve receives fuel from what component in the Continental TCM fuel injection system?

fuel control assembly

Where are the fuel discharge nozzle located in a Continental TCM fuel injection system?

in the cylinder head

What would cause the engine to not continue to run after start up?

the manual mixture control in the idle cut off position

Which component in the regulator unit is attached the poppet valve stem between the “A” and “B” chamber?

air diaphragm

What is the purpose of the sealing diaphragm?

to keep air and fuel seperated

what pressure is acting in chamber D

unmetered fuel pressure

How many metering Jets are located in the fuel control unit?

3

The function of the regulator fill valve is:

Control metered fuel pressure to the “C” chamber