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Aircraft Performance

Fuel Management, I

Each year a number of unnecessary aircraft accidents are related to fuel starvation, exhaustion or contamination. Most of them were pilot errors and could have been avoided by proper training.

There were numerous reasons for these avoidable accidents: ranging from inadequate fuel systems knowledge by the crew, preflight planning issues, takeoff and landing checks and failing to monitor consumption during flight.

Or even failing to refuel the correct quantity before the flight due to differences in systems used for indicating the amount of fuel, which has caused some aircraft to make an unexpected glide in approach and landing.

During basic flight training or conversion to a new type of aircraft for an aircraft rating the pilot must become intimately familiar with the fuel system, amount and content of the tanks, valves and unusable fuel and consumption of the engine(s) during different flight regimes.

On these pages we will discuss basic procedures to follow when gaining insight in the fuel system and properly managing it during the flight, thereby assuring a safe outcome of the flight.

Fuel Systems Knowledge

There is a difference between exhaustion and starvation: exhaustion means no more fuel onboard the aircraft and starvation means fuel onboard but not reaching the engine for some reason. This could be a closed valve, blocked line or even a leak causing an apparent high consumption.

Some aircraft (C-150, C-152) have two wing tanks but one on/off valve. Fuel should be drawn from both tanks but due to turbulence, flying out of balance, the level will not remain equal in both the tanks.

Dirty fuel

Aircraft Fuel System Detail

Contamination is just that: dirty fuel and this could clog filters causing starvation and an engine unwilling to run. Draining fuel during preflight should catch that before it becomes an issue.

Unfamiliarity with the fuel system can (and has) lead to accidents. It is very important that the pilot receives thorough training on the fuel systems of the aircraft they fly.

Type rating

Some countries conduct an aircraft type rating issue which is then added to the license of the pilot showing the types of aircraft they are licensed to fly. During training for the type rating the aircraft manual must be studied with close attention to:

  • Fuel grade, system capacity and the usable and unusable quantities
  • The number of fuel tank/system drain points and quantity measuring procedures
  • Dipstick, if any, calibrated and marked for the aircraft
  • Fuel selector operation and markings, cross-feeding procedures
  • Fuel pump operation, normal pressure and flow indications
  • Heat exchanger, if any, to combat fuel ice in cold circumstances
  • Leaning procedures and flow at different manifold/RPM combinations and altitudes
  • Manifold air pressure (MAP) and RPM for maximum range and endurance
  • Consumption of any Janitrol cabin heaters
  • Engine emergency checklists and drills
  • Procedures for flying with various configurations and fuel loads

Make sure that the person giving this instruction is qualified and has the experience on the type of aircraft, preferably with a current type rating.

If you are not current in a particular type of aircraft that you fly regularly reread the aircraft flight manual and re-familiarize yourself with special attention to the fuel system.

Maximum fuel

Keep in mind that although an aircraft can carry lots of fuel, you need to make sure that the maximum take-off weight is not exceeded. For example: the DynAero MCR-01, some models can carry up to 150 liters with long range tanks, doing that will result in not being able to take a passenger along for the flight. But then you could fly for more than six hours or so. Alone.

Written by EAI.

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