A&P Aircraft Fuel Systems 1 — Questions and Answers
Question 1: What color is 100LL aviation gasoline?
- Red
- Blue (Correct answer)
- Green
- Purple
Correct answer: Blue
100LL avgas is dyed blue to distinguish it from other aviation fuel grades and prevent misfueling.
Question 2: What type of pump is typically used as the electric boost pump in an aircraft fuel system?
- Gear-type pump
- Vane-type pump
- Centrifugal pump (Correct answer)
- Piston-type pump
Correct answer: Centrifugal pump
Electric boost pumps are typically centrifugal type, providing low-pressure fuel flow to assist the engine-driven pump during start and as a backup.
Question 3: What is an integral fuel tank?
- A removable tank that can be replaced as a unit
- A rubber bladder installed within the wing structure
- A portion of the aircraft structure that has been sealed to contain fuel (Correct answer)
- An aluminum tank riveted to the exterior of the aircraft
Correct answer: A portion of the aircraft structure that has been sealed to contain fuel
Integral fuel tanks are created by sealing a section of the aircraft's existing structure, such as a wing bay, so that the structure itself serves as the fuel container.
Question 4: What is the primary purpose of a fuel strainer (gascolator) in an aircraft fuel system?
- To increase fuel pressure before entering the carburetor
- To remove water and sediment from the fuel (Correct answer)
- To measure the quantity of fuel remaining in the tanks
- To prevent vapor lock in the fuel lines
Correct answer: To remove water and sediment from the fuel
The fuel strainer (gascolator) filters out water and sediment from the fuel to prevent contaminants from reaching the carburetor or fuel injectors and causing engine problems.
Question 5: Jet-A turbine engine fuel appears what color in its natural state?
- Blue
- Red
- Green
- Clear to straw-colored (Correct answer)
Correct answer: Clear to straw-colored
Jet-A fuel is not dyed and appears as a clear to straw-colored liquid, unlike aviation gasoline which is color-coded by grade.
Question 6: What is 'vapor lock' in an aircraft fuel system?
- A safety lock on the fuel filler cap to prevent overfilling
- A condition where fuel vaporizes in the lines, blocking adequate fuel flow to the engine (Correct answer)
- A blockage caused by debris in the fuel vent line
- A mechanical seizure of the fuel selector valve
Correct answer: A condition where fuel vaporizes in the lines, blocking adequate fuel flow to the engine
Vapor lock occurs when fuel vaporizes within the fuel lines or pump, creating a vapor barrier that prevents adequate liquid fuel flow to the engine.
Question 7: What is the purpose of fuel tank vents in an aircraft fuel system?
- To release excess fuel pressure during climb
- To provide a drain point for water removal from the tank
- To maintain atmospheric pressure in the tank and allow proper fuel flow as fuel is consumed (Correct answer)
- To allow fuel quantity gauges to reference atmospheric pressure
Correct answer: To maintain atmospheric pressure in the tank and allow proper fuel flow as fuel is consumed
Fuel tank vents maintain atmospheric pressure inside the tanks, preventing tank collapse from internal vacuum and ensuring consistent fuel flow to the engine as fuel is consumed.
A&P Aircraft Fuel Systems 1
What color is 100LL aviation gasoline?