FUEL AWARENESS

Acknowledgements: AOPA USA AIR SAFETY INSTITUTE

1. Know What’s in Your Fuel Tanks
That means making sure that no water has got into the tanks, and verifying that the tanks haven’t been filled with the wrong fuel.

2. Know for certain how much usable fuel is on board
Fuel computers will tell you how much you’re burning and how much you have left, but the pilot still needs to input the starting fuel quantity.
·     A calibrated dipstick is a good way to measure fuel, but be sure it’s calibrated for your airplane.
·     Departing with full tanks is not always possible due to weight and balance limitations.
·     And what about the previous pilot who tells you “I only flew an hour on full tanks”? Were they full? Did he/she lean the mixture? Verify: It’s your safety and certificate on the line.
·     If using an unfamiliar airplane, AOPA Air Safety Foundation recommends you add one or two gallons per hour to your computed fuel consumption until you see how much it does burn.

3. Know Your Airplane’s Fuel System
·     All airplanes have a means of selecting which tank or combination of tanks is in use, and of shutting off all fuel to the engine. Some (like the Cessna 150/152) feed from two tanks at the same time. The fuel selector valve has only On/Off positions. Others have Off, Left, Both, and Right fuel selector positions. In most carburetted high-wing designs, gravity feeds fuel to the engine. But If the fuel supply is lower than the engine, fuel must be pumped
·     So, fuel management on a Cessna 150 is easy: Two wing tanks simultaneously gravity-feeding fuel to the engine, with the fuel selector either on or off.
·     But a low-wing single with two main, two wing-auxiliary, two after-market tip tanks, an engine-driven primary fuel pump, electric boost pump, and electric fuel transfer pumps? It’s not surprising that pilots have made forced landings with fuel still available!
·     The location of the fuel selector valve varies with airplane type, and in some designs the valve is hard to see. To avoid fuel-starvation make sure you are moving the fuel selector correctly.
·     Switching tanks should not be done at low altitudes: Perform pre-landing fuel tank selection before reaching pattern altitude

4. Update Your Fuel Status Regularly.
Your POH shows fuel consumption for various power settings. But remember: Fuel consumption figures are based on a properly leaned engine operating at a specific power setting. Winds are rarely exactly as forecast, and weather deviations add miles and minutes to your trip. AOPA Air Safety Foundation recommends that pilots evaluate the fuel status as follows:
·     In flight, recalculate range and endurance hourly
·     Compare your range calculation with the distance to your destination, to make sure of an adequate fuel reserve. By doing this, you can make timely adjustments to your flight plan for un-forecast winds, or weather deviations
·     Estimate how much fuel your airplane will take at each fuel stop. When you refuel, comparing this estimate with what actually goes into the tanks is an excellent way to develop “fuel sense”
 
5. Always Land with Adequate Reserve Fuel
AOPA Air Safety Foundation recommends that pilots always LAND with at least one hour of fuel in the tanks. This does not mean searching for an airport when approaching the one-hour reserve: It means being on the ground.

6. Leaning
It’s impossible to achieve “book” performance, range, or endurance unless you lean the mixture.
·     Leaning manually: On basic airplanes, set cruise power and lean the mixture until the engine runs rough. Then slowly enrich the mixture until the engine smooths out. You may see a slight increase in rpm before the engine starts to roughen. If you later need to climb to a higher cruising altitude, enrich the mixture before adding power (if you’re at or above 75 percent power) and then lean again when level at your new altitude.
·     Leaning for take-off: At high-density-altitude airports, you’ll have to lean before take-off to maximise engine power. Consult your POH for details.

7. Carburettor Heat
As air moves through a carburettor its temperature drops and, if conditions are right, water vapour in the air can form ice. Most carburetted aircraft are equipped with a control that routes heated air to the carburettor to melt the ice and keep it from re-forming. This results in a richer mixture (and increased consumption) because the heated air is less dense than ambient air. Pilots should lean while operating with carb heat and enrich when it’s no longer needed.

8. Extending Range
Long deviations around weather, stronger than forecast headwinds, or discovery of a low fuel condition may require you to maximize fuel economy. Let’s look at some ways to conserve fuel:
·     Slow down: You’ll burn less fuel if you cruise at a lower power setting.
·     Fly with the wind: If you have a choice of equidistant fuel stops, pick the one that’s downwind. You may have to back-track, but you’ll burn less fuel and get there faster.
·     Lean for best economy: Consult the POH for best economy/long endurance power settings and leaning procedures.

Obviously, pilots should adjust their flight plan before fuel becomes a critical issue, but if you’re low on fuel or, worse, dipping into the reserve, land as soon as possible. Don’t wait for the FBO with the best price or the preferred credit card!

FLY SAFE!
Tony Birth