Planes have huge fuel tanks to enable them to fly far. The tanks are in the wings and sometimes behind the forward cargo compartment. The center tank of the Boeing 777 is so big that you can stand up and walk around in it. So how much does it cost to fill her up?
Today I followed the HZ-AKC for refueling. The refueling process is quite lengthy. It took almost an hour to tow the aircraft out, refuel and re dock it back into the hangar. But I’ll talk about the refueling process since it’s pretty interesting. I don’t have pictures to show but I’ve got some diagrams to simplify things.
The grey shaded areas are fuel tanks.
First, in order to refuel the aircraft, it must be towed to a suitable refueling area. Planes cannot be refueled in the hangars because it’s dangerous. In case of a fire, you might lose the plane and the hangar altogether. Once the plane is at a suitable area, ground power is applied so the plane’s computers can operate the refueling valves.
Next, the bowser comes. The bowser is a mobile fuel pump. The one we used today obtained its supply of fuel from underground storage tanks. Some carry their own supply in big tanks, like those petrol tankers you see on the road. The bowser will connect its hoses to the refueling nozzle. But wait. How do you know how much you want?
The refueling panel with the 2 hoses connected.
Now this is the interesting part. You actually tell the plane how much fuel you want and then the plane will calculate and allocate the correct amount to each tanks (right, left and center). The bowser, unlike normal petrol pumps that supply a fixed amount of fuel (say RM50), will keep on pumping until the plane stops the fuel flow by closing the refueling valves. There is a meter on the bowser that tells how much fuel has been transferred so they will know how much to charge. So basically the plane’s computer will be in charge of the whole refueling process. The bowser pumps fuel pretty fast. It will transfer 20 liters or more in about 1 second.
I thought JET A1 was cheap. Turns out its not. It costs RM4+ per liter. And today we filled in 55 tons of JET A1. Assuming the average specific gravity of 0.79, that amounts to almost 70000liters (69620) of JET A1!! And at RM4 per liter, that’s RM280k worth of fuel! That’s more than a quarter of a million! And jet engines burn fuel pretty fast.
According to an engineer, the 747 uses 4 tons of fuel for take-off for ONE of its engines. So that means 16 tons of fuel is needed by the 747 just for take-off and to reach cruising altitude. While cruising, ONE engine drinks up 1 ton of fuel every hour, so that makes 4 tons per hour. 55 tons of fuel will give a 747 close to 10 hours of flight including take-off. RM280k for 10 hours. I wonder how airaisa makes money.
Pilots are usually the ones who calculate the amount of fuel needed for a journey. They will take in just about enough for the trip. Too much will slow the plane down and waste fuel and they have to dump fuel if the plane is too heavy for landing, too little and you’ll never reach your destination. They will let the bowser know how much fuel they want, but the company will be paying for it. Continue reading