A&P Aircraft Fuel Systems 2 — Questions and Answers
Question 1: Which type of fuel metering system is most susceptible to carburetor ice formation?
- Pressure-type carburetor
- Float-type carburetor (Correct answer)
- Continuous-flow fuel injection
- Direct cylinder fuel injection
Correct answer: Float-type carburetor
Float-type carburetors are most susceptible to icing because fuel vaporization combined with the pressure drop at the venturi causes significant temperature decreases that promote ice formation.
Question 2: What is the primary purpose of a crossfeed fuel system in a multi-engine aircraft?
- To transfer fuel between tanks for lateral balance only
- To allow any engine to draw fuel from any tank on the aircraft (Correct answer)
- To provide an alternate fuel path in case the main pump fails
- To preheat fuel before it enters the turbine engine
Correct answer: To allow any engine to draw fuel from any tank on the aircraft
A crossfeed system allows each engine to draw fuel from any tank, providing fuel management flexibility and enabling continued operation in the event of a fuel pump or engine failure.
Question 3: How does a fuel injection system differ from a float-type carburetor in delivering fuel?
- Fuel injection meters and delivers fuel under pressure directly to the intake ports or cylinders (Correct answer)
- Fuel injection uses a float chamber to control fuel level before the venturi
- Fuel injection requires a larger air filter and intake manifold
- Fuel injection is only certified for use on turbine engines
Correct answer: Fuel injection meters and delivers fuel under pressure directly to the intake ports or cylinders
Fuel injection systems meter and deliver fuel under pressure directly to the intake port or cylinder, providing more precise fuel metering and eliminating carburetor icing risk.
Question 4: What color is 80/87 aviation gasoline?
- Blue
- Red (Correct answer)
- Green
- Orange
Correct answer: Red
Grade 80/87 aviation gasoline is dyed red to distinguish it from higher octane grades such as 100LL (blue) and 100/130 (green).
Question 5: What is the function of the fuel selector valve in an aircraft fuel system?
- To regulate fuel pressure delivered to the engine
- To select which fuel tank supplies fuel to the engine (Correct answer)
- To control the fuel-to-air mixture ratio
- To bypass the engine-driven pump during engine start
Correct answer: To select which fuel tank supplies fuel to the engine
The fuel selector valve allows the pilot or crew to choose which fuel tank will supply fuel to the engine, enabling proper fuel management and tank balancing.
Question 6: Which type of fuel is used in turbine (jet) engines?
- 100LL aviation gasoline
- 80/87 aviation gasoline
- Jet-A or Jet-A1 kerosene-based fuel (Correct answer)
- High-sulfur diesel fuel
Correct answer: Jet-A or Jet-A1 kerosene-based fuel
Turbine engines use kerosene-based fuels such as Jet-A or Jet-A1, which have different energy content, flash point, and combustion characteristics than aviation gasoline.
Question 7: What does a fuel quantity transmitter (sender unit) do in an aircraft fuel system?
- It transmits fuel pressure readings to the cockpit indicator
- It converts the fuel level in the tank to an electrical signal that drives the cockpit fuel quantity gauge (Correct answer)
- It transmits fuel temperature data to the engine control unit
- It controls the fuel flow rate from the tank to the boost pump
Correct answer: It converts the fuel level in the tank to an electrical signal that drives the cockpit fuel quantity gauge
A fuel quantity transmitter uses a float or capacitance-type sensor to convert the fuel level in the tank into an electrical signal, which is then displayed on the cockpit fuel quantity gauge.
A&P Aircraft Fuel Systems 2
Which type of fuel metering system is most susceptible to carburetor ice formation?