Fuel Systems Summary

  • Fuel System Overview
    • Purpose: Supply clean fuel at correct pressure to engines during flight phases.
    • Components:
    • Storage: Tanks, filters, caps.
    • Distribution: Plumbing, pumps, valves.
    • Damp: Components for dumping fuel.
    • Indication: Components for fuel quantity, temperature, and pressure.
  • Functional Requirements
    • Supply enough fuel at specified pressure and cleanliness.
    • Regulations:
    • Supply 125% of maximum expected flow.
    • Maneuvers necessitate consideration of pressure gradients.
  • Classification of Fuel Systems
    • Gravity-Feed Systems: Uses gravity; must be positioned high enough.
    • Pressure-Feed Systems: Utilizes pumps; essential for high-powered aircraft.
  • Components of Fuel Systems
    • Tanks: Integral, rigid removable, or bladder types.
    • Pumps: Transfer fuel; various types including centrifugal impeller.
  • Fuel Distribution
    • Engine Feed: Gravity or pressure feed systems.
    • Fuel Transfer: Cross-feed system for flexibility in multi-engine aircraft.
  • Refueling Processes
    • Over-Wing Refueling: Gravity-based, typically for small aircraft.
    • Pressure Refueling: Quick filling using pressure; preferred method.
    • Defueling: Opposite to refueling; necessary for maintenance.
  • Vent and Jettison Systems
    • Open vent systems prevent pressure issues during altitude changes.
    • Fuel jettison for emergencies to reduce landing weight.
  • Fuel Properties
    • Characteristics depend on origin and refinement processes.
    • Seasonal temperature affects density significantly.
    • Common fuels: AVGAS (for piston engines), AVTUR and AVTAG (for jet engines).
  • Key Fuel System Characteristics
    • Reliable supply crucial for sustained flight.
    • Modes of operation: Pressurization, transfer, jettisoning, and in-flight refueling.
  • Monitoring Systems
    • Level sensors and flow meters track fuel levels and flow rates.
    • Filters and strainers remove impurities from fuel.
  • Safety Measures
    • Overpressure relief valves prevent the risk of tank ruptures.
    • Non-return valves maintain proper system operation without reverse fuel flow.