A&P A&P - Aircraft and Powerplant Aircraft Fuel Systems 1 — Questions and Answers
Question 1: What grade of aviation gasoline (avgas) is identified by its blue color?
- 100LL (low-lead) (Correct answer)
- 80/87
- 100/130
- 115/145
Correct answer: 100LL (low-lead)
100LL avgas is dyed blue for identification and is the most widely used grade for piston-powered aircraft.
Question 2: What is the primary purpose of a fuel system boost pump?
- Provide positive fuel pressure to the engine-driven pump and prevent vapor lock (Correct answer)
- Replace the engine-driven pump during normal cruise
- Filter water from the fuel before engine combustion
- Pressurize the fuel tanks during high-altitude flight
Correct answer: Provide positive fuel pressure to the engine-driven pump and prevent vapor lock
Boost pumps supply positive inlet pressure to the engine-driven pump and prevent vapor lock, especially during takeoff and high-altitude operations.
Question 3: What does a fuel selector valve set to 'BOTH' mean on a single-engine aircraft with two wing tanks?
- Fuel is drawn from both tanks simultaneously through a crossfeed manifold (Correct answer)
- Both tanks are isolated to prevent crossfeed
- The left tank feeds only, with the right tank as reserve
- Fuel flows only to the boost pump, not the engine
Correct answer: Fuel is drawn from both tanks simultaneously through a crossfeed manifold
The BOTH position opens both tank feeds simultaneously, drawing fuel from both wing tanks at the same time.
Question 4: Where is the fuel tank sump drain located and why?
- At the lowest point of the tank to collect and drain water and sediment (Correct answer)
- At the top of the tank to vent vapors
- At the tank outlet to protect the fuel selector valve
- At the fuel cap to allow overflow during refueling
Correct answer: At the lowest point of the tank to collect and drain water and sediment
The sump drain is at the lowest point of the fuel tank so that water, which is denser than fuel, accumulates there and can be drained during preflight.
Question 5: What is the maximum allowable water contamination check procedure during aircraft preflight?
- Drain a sample from each sump into a clear container and visually check for water globules or cloudiness (Correct answer)
- Use a fuel tester strip inserted into the fuel cap opening
- Check the fuel color with a UV light for water fluorescence
- Measure fuel specific gravity with a hydrometer
Correct answer: Drain a sample from each sump into a clear container and visually check for water globules or cloudiness
Preflight fuel sampling involves draining fuel into a clear tester and checking visually for water (appears as globules or cloudiness at the bottom).
Question 6: What type of fuel does a turbine (jet) engine aircraft use?
- Jet-A (kerosene-based) (Correct answer)
- 100LL avgas
- Mogas (automotive gasoline)
- Jet B (wide-cut gasoline blend)
Correct answer: Jet-A (kerosene-based)
Most commercial and turbine-powered aircraft use Jet-A, a kerosene-based fuel with a high flash point and good cold-weather properties.
A&P A&P - Aircraft and Powerplant Aircraft Fuel Systems 1
What grade of aviation gasoline (avgas) is identified by its blue color?