AMT Engine Fuel Metering Systems 3

Question 1

What effect does carburetor ice formation have on engine operation?

Accepted Answer

Causes a progressive loss of engine power due to reduced airflow and mixture enrichment

Answer

Carburetor ice forms in the venturi throat, restricting airflow and progressively richening the mixture, causing a loss of power that worsens if untreated.

Question 2

In a fuel injection system, what is the result of a clogged injector nozzle on the affected cylinder?

Accepted Answer

That cylinder will run lean, potentially causing overheating or misfiring

Answer

A clogged injector restricts fuel to that cylinder, creating a lean condition that can cause overheating, rough running, or detonation.

Question 3

The fuel-air mixture control in a float carburetor changes the mixture by:

Accepted Answer

Moving a needle or plate that restricts the fuel passage in the main discharge circuit

Answer

The mixture control needle or plate restricts or blocks the passage between the float chamber and the main discharge nozzle to lean or richen the mixture.

Question 4

Which type of carburetor system is LEAST susceptible to carburetor ice because the fuel-air mixing does not occur in the venturi?

Accepted Answer

Direct fuel injection system

Answer

Direct fuel injection introduces fuel at each cylinder intake port rather than in a venturi, so the cooling and ice-forming conditions present in carburetors do not occur.

Question 5

An automatic mixture control (AMC) in a carburetor compensates for altitude by:

Accepted Answer

Using an aneroid bellows to lean the mixture as air density decreases with altitude

Answer

The AMC uses an aneroid bellows that expands as ambient pressure decreases, mechanically leaning the mixture to maintain the correct fuel-air ratio with altitude.

(AMT) Aviation Maintenance Technician Practice Test

(AMT) Aviation Maintenance Technician Practice Test

AMT Engine Fuel Metering Systems 3