Aircraft Fuel Systems Flashcards
7 cards from real AMT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Aircraft Fuel Systems flashcards as text
What is the primary function of baffles installed inside aircraft fuel tanks?
Answer: To reduce fuel sloshing and maintain fuel near the outlet during aircraft maneuvering
Baffles reduce fuel movement (sloshing) during banking and pitch changes, ensuring fuel stays near the tank outlet and pickup tube to prevent momentary fuel starvation during maneuvering flight.
During a preflight fuel sample inspection, what indicates water contamination in aviation fuel?
Answer: A distinct clear layer at the bottom or cloudiness throughout the fuel sample
Water contamination appears as a separate clear layer settled at the bottom of the sample (since water is denser than fuel) or as cloudiness/haze when water is dispersed in small droplets throughout the fuel.
What type of pump is most commonly used as the engine-driven fuel pump on piston aircraft engines?
Answer: Vane-type (rotary vane) pump
Vane-type rotary pumps are the standard engine-driven fuel pump for piston aircraft because they provide consistent pressure, handle small amounts of vapor without losing prime, and are mechanically simple.
What is the purpose of a firewall fuel shutoff valve in a single-engine aircraft?
Answer: To allow the pilot to immediately stop all fuel flow to the engine from the cockpit during emergencies
The firewall shutoff valve (fuel selector off or dedicated shutoff) allows the pilot to cut fuel flow to the engine instantly from the cockpit — essential for engine fire suppression or controlled emergency shutdown.
What does the 'LL' designation in AVGAS 100LL stand for?
Answer: Low Lead — indicating reduced lead content compared to 100/130 aviation gasoline
LL stands for Low Lead; AVGAS 100LL contains approximately 2.0 grams of tetraethyl lead per gallon, significantly less than the 4.0 g/gal in older 100/130 grade, while still meeting the 100 octane performance requirement.
What is the function of an ejector pump (jet pump) used in aircraft fuel transfer systems?
Answer: To transfer fuel from auxiliary or tip tanks to main tanks using motive flow energy with no moving parts
An ejector pump uses venturi action: high-pressure motive flow from the main boost pump creates suction that draws fuel from auxiliary tanks into the main tank, requiring no electrical power or moving parts.
How does a capacitance-type fuel quantity gauging system determine fuel quantity in an aircraft tank?
Answer: By measuring the electrical capacitance between probes, which changes proportionally as the fuel-to-air ratio in the tank changes
Capacitance fuel quantity systems measure the dielectric constant between submerged probe plates; fuel and air have different dielectric properties, so as fuel level changes, capacitance changes proportionally, indicating quantity accurately even with fuel density variations.