systems
The Aircraft Fuel System
How fuel gets from the tanks to the engine, the role of the fuel pumps, and managing fuel in flight.
The fuel system stores fuel and delivers it reliably to the engine in all attitudes and conditions. Light-aircraft systems are either gravity-fed (high wing) or pump-fed (low wing), with a few common components.
The components
- Tanks — usually in the wings, with vents (a blocked vent can stop fuel flow) and sumps for draining water and sediment.
- Fuel selector — left, right, both or off; lets you manage and balance fuel.
- Fuel pumps — gravity-fed aircraft may have none; low-wing aircraft have an engine-driven pump plus an electric boost pump for starting, takeoff, landing and backup.
- Strainer/gascolator, primer, and fuel-flow/pressure gauges.
Managing fuel
- Sump and inspect before flight — check for water (it sinks below the fuel) and correct color/grade.
- Use the selector to keep the aircraft laterally balanced and to feed from a known-good tank for critical phases.
- Lean the mixture per the POH to manage consumption, and plan reserves (91.151).
Common pitfalls
- Fuel starvation (fuel aboard but not reaching the engine — wrong selector, blocked vent) versus exhaustion (no fuel left).
- Misjudging usable fuel or trusting gauges over a time/burn calculation — use the fuel planning tool.
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*Reference and training only — not for navigation. Always consult the current AIM, FAR/AIM, your aircraft’s POH/AFM and a certificated flight instructor.*
Official sources
For reference and training only — verify current requirements with the official authority. Last reviewed June 7, 2026.