AME Aircraft Fuel Systems and Fire Protection 1 — Questions and Answers
Question 1: What is the primary function of a fuel boost pump in an aircraft fuel system?
- To maintain positive fuel pressure, prevent vapor lock, and supply the engine-driven pump (Correct answer)
- To filter contaminants from fuel before engine delivery
- To transfer fuel between tanks for lateral balance only
- To measure fuel quantity electronically
Correct answer: To maintain positive fuel pressure, prevent vapor lock, and supply the engine-driven pump
Fuel boost pumps maintain positive pressure in the supply line to prevent vapor lock and ensure adequate fuel delivery to the engine-driven pump, especially during takeoff and climb.
Question 2: Introducing the wrong fuel type into an aircraft (e.g., Jet-A into an avgas aircraft) is specifically called:
- Cross-contamination
- Misfueling (Correct answer)
- Fuel substitution
- Incorrect servicing
Correct answer: Misfueling
Misfueling refers to the introduction of the wrong fuel type into an aircraft, which can cause engine failure and is one of the most serious maintenance errors.
Question 3: Which component in a fuel system prevents fuel from flowing backward from the engine toward the tanks?
- Fuel strainer
- Check valve (Correct answer)
- Fuel selector valve
- Firewall shutoff valve
Correct answer: Check valve
Check valves are one-way valves that allow fuel flow in only one direction, preventing reverse flow that could drain lines or allow unintended fuel migration between tanks.
Question 4: What does the designation 'AVGAS 100LL' mean?
- Aviation gasoline with 100 octane rating and low lead content (Correct answer)
- Aviation gasoline for use below 10,000 feet only
- Aviation gasoline approved for 100-hour inspection intervals
- Aviation gasoline meeting 100 kPa pressure specification
Correct answer: Aviation gasoline with 100 octane rating and low lead content
AVGAS 100LL stands for aviation gasoline with a 100 octane rating and 'low lead' formulation, containing less tetraethyl lead than the older 100/130 grade.
Question 5: How is a fuel system water contamination check typically performed?
- Sending a sample to a laboratory for analysis
- Draining fuel from sumps into a clear container and visually checking for water separation (Correct answer)
- Using a refractometer to measure water content
- Checking fuel color with a spectrometer
Correct answer: Draining fuel from sumps into a clear container and visually checking for water separation
Water in fuel separates due to its higher density and appears as a distinct layer or globules at the bottom of a clear fuel sample drained from the lowest tank sump point.
Question 6: The primary purpose of a firewall fuel shutoff valve is to:
- Regulate fuel pressure to the carburetor
- Isolate the fuel supply from the engine compartment in case of fire or emergency (Correct answer)
- Prevent fuel flow when the engine is not running
- Balance fuel flow between multiple carburetors
Correct answer: Isolate the fuel supply from the engine compartment in case of fire or emergency
The firewall shutoff valve allows the crew to cut off fuel flow to the engine compartment in an emergency, starving a fire of its fuel source.
AME Aircraft Fuel Systems and Fire Protection 1
What is the primary function of a fuel boost pump in an aircraft fuel system?