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.
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.
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.
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.
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!