12.28 Fuel System Components

12.28.2 Describe the function of the following components of a simple fuel system:

(a) fuel selector valve, supply line, strainer and strainer drain;

• Fuel Selector Valve:
  Allows the pilot to select which fuel tank supplies the engine (e.g. LEFT, RIGHT, BOTH, or OFF). It enables fuel management and isolation of tanks if required.
• Supply Line:
  Carries fuel from the selected tank, through the system, to the engine. It provides the path for continuous fuel flow.
• Strainer (Fuel Filter):
  Removes water, dirt, and contaminants from the fuel before it reaches the engine, protecting engine components and ensuring clean fuel supply.
• Strainer Drain:
  A drain point used to check and remove water or sediment from the strainer during pre-flight inspection. It ensures the fuel system remains free of contamination.

Summary:
These components work together to select, deliver, clean, and check fuel, ensuring a safe and reliable fuel supply to the engine.

(b) fuel primer, engine-driven pump, auxiliary (boost) pumps.

• Fuel Primer:
  A hand-operated pump used to inject fuel directly into the induction system or cylinders for starting. It provides a richer mixture to assist engine start, particularly in cold conditions.
• Engine-Driven Pump:
  The primary fuel pump, mechanically driven by the engine. It supplies fuel from the tanks to the carburettor or fuel injection system during normal operation.
• Auxiliary (Boost) Pump:
  An electrically driven backup or support pump. It is used to:
  • Provide positive fuel pressure during engine start
  • Assist during critical phases (e.g. take-off, landing)
  • Act as a backup in case of engine-driven pump failure