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Aircraft Performance

Onboard Fuel Management

Each year a number of aircraft accidents are related to starvation, exhaustion or contamination. 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.

As preflight of an aircraft is important, preflighting the fuel system is equally so. During the pre-takeoff check the pilot verifies the correct tank to use during engine start and takeoff.

Pre-takeoff checks

Aircraft Checklist

Having an engine failure just after takeoff could be the worst possible time. A number of these situations were related due to fuel problems and the majority was selecting an almost empty tank (or even switching fuel off due to incorrectly marked selectors), and in aircraft with more than one tank to select. Contaminated fuel has also caused problems in the past.

A lot of these situations can be avoided by using the correct preflight and pre-takeoff checks.

The list below is not complete but these checks are commonly done when verifying fuel supply and switching tanks.

  • Select the least-full tank before engine start, this will make sure that this tank can feed the engine. Also listen for the fuel pump when switched on, when the engine is running you will not hear the fuel pump. Check for a rise in and a stable pressure. With a gravity fed system there will always be some low pressure due to the design.
  • Change to the fullest tank before run-up. This will stabilize fuel flow from this tank. Visually check when moving the fuel selector. Selection of the wrong tank (especially when flying different aircraft with similar fuel systems) can be deadly. If you notice, after takeoff, that the wrong tank was selected, wait until you are at a safe height, then switch the fuel pump on and switch tanks. When switching the fuel pump off, keep you hand near the switch. The engine pump could have failed.
  • If using a timer or watch now is the time to start it or note the time as to be sure not to forget to switch tanks in time.
  • Keep monitoring the quantity gauges, pressures and flow for normal indications. Scan the pressure during takeoff roll and keep the fuel pump on until a safe height is reached and the aircraft is cleaned up.
  • When flying low or over inhospitable terrain, switch on the fuel pump.

The reason for having the the fuel pump on when switching tanks is to remove any air that may have collected in the fuel lines which could cause temporarily starvation and probably an anxious moment with the pilot. Not to mention what would happen to the state of mind of your passengers.

It is important to be totally familiar with the fuel system of the aircraft you fly. Be sure to know the number of tanks and quantities, normal fuel flow, number of fuel pumps (the Rotax 914 uses two electrical in series configured pumps) and check the emergency procedures for fuel related engines failures.

Calibration table

Keep the POH or aircraft manual nearby should any confusion arise about the amount of fuel during the flight. Herein you should find the calibration table for the fuel system which relates indicated with actual fuel onboard.

Although this table is only valid when the aircraft is flying straight and level (or on level ground), it will give you a good idea of how much is onboard during the flight.

J-Air Fuel Hawk


If using a dipstick to check fuel levels, it should be calibrated and marked with the aircraft registration. The reason for marking a dipstick is simple, not all aircraft and their tanks are created or formed equal, or have the same contents.
If you are using a J-Air fuelhawk then you need to created a simple chart which converts the dipstick indication to real gallons. Easy!

Written by EAI.



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