A&P Aircraft Fuel Systems

Question 1

What is the purpose of a fuel system boost pump on a reciprocating engine aircraft?

Accepted Answer

To provide fuel pressure for starting and as a backup if the engine-driven pump fails

Answer

Electric boost pumps prime the fuel system for starting and serve as an emergency backup if the engine-driven mechanical fuel pump fails in flight.

Question 2

Which grade of aviation gasoline (AVGAS) is dyed blue and used in most current general aviation piston aircraft?

Accepted Answer

100LL (Low Lead)

Answer

100LL (100 Low Lead) AVGAS is dyed blue and is the standard fuel for most piston-powered general aviation aircraft in the United States.

Question 3

What is the primary reason fuel sumps must be drained during preflight inspection?

Accepted Answer

To check for and remove water and sediment that accumulate at the lowest points of the fuel system

Answer

Water and contaminants are denser than fuel and settle at the lowest points (sumps), so draining removes these before flight to prevent engine fuel starvation.

Question 4

What does a fuel crossfeed valve allow on a multi-engine aircraft?

Accepted Answer

It allows fuel from one wing tank to feed the engine on the opposite wing

Answer

A crossfeed valve allows either engine to draw fuel from either wing tank, enabling the crew to feed both engines from one tank or maintain fuel balance.

Question 5

What is the function of a fuel system vent?

Accepted Answer

To equalize tank pressure with ambient air pressure, preventing collapse or structural damage during fuel consumption and temperature changes

Answer

Fuel tank vents prevent a vacuum or pressure differential from forming as fuel is consumed or temperature changes, which could collapse the tank walls or prevent fuel flow to the engine.

A&P - Aircraft and Powerplant Certification Practice Test

A&P - Aircraft and Powerplant Certification Practice Test

A&P Aircraft Fuel Systems